text: /*-------------------------------------------------------------------------
   *
   * pl_exec.c		- Executor for the PL/pgSQL
   *			  procedural language
   *
   * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   *
   * IDENTIFICATION
   *	  src/pl/plpgsql/src/pl_exec.c
   *
   *-------------------------------------------------------------------------
   */
  
  #include "postgres.h"
  
  #include <ctype.h>
  
  #include "access/detoast.h"
  #include "access/htup_details.h"
  #include "access/transam.h"
  #include "access/tupconvert.h"
  #include "catalog/pg_proc.h"
  #include "catalog/pg_type.h"
  #include "commands/defrem.h"
  #include "executor/execExpr.h"
  #include "executor/spi.h"
  #include "executor/spi_priv.h"
  #include "funcapi.h"
  #include "mb/stringinfo_mb.h"
  #include "miscadmin.h"
  #include "nodes/nodeFuncs.h"
  #include "optimizer/optimizer.h"
  #include "parser/parse_coerce.h"
  #include "parser/parse_type.h"
  #include "parser/scansup.h"
  #include "plpgsql.h"
  #include "storage/proc.h"
  #include "tcop/tcopprot.h"
  #include "tcop/utility.h"
  #include "utils/array.h"
  #include "utils/builtins.h"
  #include "utils/datum.h"
  #include "utils/fmgroids.h"
  #include "utils/lsyscache.h"
  #include "utils/memutils.h"
  #include "utils/rel.h"
  #include "utils/snapmgr.h"
  #include "utils/syscache.h"
  #include "utils/typcache.h"
  
  typedef struct
  {
  	int			nargs;			/* number of arguments */
  	Oid		   *types;			/* types of arguments */
  	Datum	   *values;			/* evaluated argument values */
  	char	   *nulls;			/* null markers (' '/'n' style) */
  } PreparedParamsData;
  
  /*
   * All plpgsql function executions within a single transaction share the same
   * executor EState for evaluating "simple" expressions.  Each function call
   * creates its own "eval_econtext" ExprContext within this estate for
   * per-evaluation workspace.  eval_econtext is freed at normal function exit,
   * and the EState is freed at transaction end (in case of error, we assume
   * that the abort mechanisms clean it all up).  Furthermore, any exception
   * block within a function has to have its own eval_econtext separate from
   * the containing function's, so that we can clean up ExprContext callbacks
   * properly at subtransaction exit.  We maintain a stack that tracks the
   * individual econtexts so that we can clean up correctly at subxact exit.
   *
   * This arrangement is a bit tedious to maintain, but it's worth the trouble
   * so that we don't have to re-prepare simple expressions on each trip through
   * a function.  (We assume the case to optimize is many repetitions of a
   * function within a transaction.)
   *
   * However, there's no value in trying to amortize simple expression setup
   * across multiple executions of a DO block (inline code block), since there
   * can never be any.  If we use the shared EState for a DO block, the expr
   * state trees are effectively leaked till end of transaction, and that can
   * add up if the user keeps on submitting DO blocks.  Therefore, each DO block
   * has its own simple-expression EState, which is cleaned up at exit from
   * plpgsql_inline_handler().  DO blocks still use the simple_econtext_stack,
   * though, so that subxact abort cleanup does the right thing.
   */
  typedef struct SimpleEcontextStackEntry
  {
  	ExprContext *stack_econtext;	/* a stacked econtext */
  	SubTransactionId xact_subxid;	/* ID for current subxact */
  	struct SimpleEcontextStackEntry *next;	/* next stack entry up */
  } SimpleEcontextStackEntry;
  
  static EState *shared_simple_eval_estate = NULL;
  static SimpleEcontextStackEntry *simple_econtext_stack = NULL;
  
  /*
   * Memory management within a plpgsql function generally works with three
   * contexts:
   *
   * 1. Function-call-lifespan data, such as variable values, is kept in the
   * "main" context, a/k/a the "SPI Proc" context established by SPI_connect().
   * This is usually the CurrentMemoryContext while running code in this module
   * (which is not good, because careless coding can easily cause
   * function-lifespan memory leaks, but we live with it for now).
   *
   * 2. Some statement-execution routines need statement-lifespan workspace.
   * A suitable context is created on-demand by get_stmt_mcontext(), and must
   * be reset at the end of the requesting routine.  Error recovery will clean
   * it up automatically.  Nested statements requiring statement-lifespan
   * workspace will result in a stack of such contexts, see push_stmt_mcontext().
   *
   * 3. We use the eval_econtext's per-tuple memory context for expression
   * evaluation, and as a general-purpose workspace for short-lived allocations.
   * Such allocations usually aren't explicitly freed, but are left to be
   * cleaned up by a context reset, typically done by exec_eval_cleanup().
   *
   * These macros are for use in making short-lived allocations:
   */
  #define get_eval_mcontext(estate) \
  	((estate)->eval_econtext->ecxt_per_tuple_memory)
  #define eval_mcontext_alloc(estate, sz) \
  	MemoryContextAlloc(get_eval_mcontext(estate), sz)
  #define eval_mcontext_alloc0(estate, sz) \
  	MemoryContextAllocZero(get_eval_mcontext(estate), sz)
  
  /*
   * We use a session-wide hash table for caching cast information.
   *
   * Once built, the compiled expression trees (cast_expr fields) survive for
   * the life of the session.  At some point it might be worth invalidating
   * those after pg_cast changes, but for the moment we don't bother.
   *
   * The evaluation state trees (cast_exprstate) are managed in the same way as
   * simple expressions (i.e., we assume cast expressions are always simple).
   *
   * As with simple expressions, DO blocks don't use the shared hash table but
   * must have their own.  This isn't ideal, but we don't want to deal with
   * multiple simple_eval_estates within a DO block.
   */
  typedef struct					/* lookup key for cast info */
  {
  	/* NB: we assume this struct contains no padding bytes */
  	Oid			srctype;		/* source type for cast */
  	Oid			dsttype;		/* destination type for cast */
  	int32		srctypmod;		/* source typmod for cast */
  	int32		dsttypmod;		/* destination typmod for cast */
  } plpgsql_CastHashKey;
  
  typedef struct					/* cast_hash table entry */
  {
  	plpgsql_CastHashKey key;	/* hash key --- MUST BE FIRST */
  	Expr	   *cast_expr;		/* cast expression, or NULL if no-op cast */
  	CachedExpression *cast_cexpr;	/* cached expression backing the above */
  	/* ExprState is valid only when cast_lxid matches current LXID */
  	ExprState  *cast_exprstate; /* expression's eval tree */
  	bool		cast_in_use;	/* true while we're executing eval tree */
  	LocalTransactionId cast_lxid;
  } plpgsql_CastHashEntry;
  
  static MemoryContext shared_cast_context = NULL;
  static HTAB *shared_cast_hash = NULL;
  
  /*
   * LOOP_RC_PROCESSING encapsulates common logic for looping statements to
   * handle return/exit/continue result codes from the loop body statement(s).
   * It's meant to be used like this:
   *
   *		int rc = PLPGSQL_RC_OK;
   *		for (...)
   *		{
   *			...
   *			rc = exec_stmts(estate, stmt->body);
   *			LOOP_RC_PROCESSING(stmt->label, break);
   *			...
   *		}
   *		return rc;
   *
   * If execution of the loop should terminate, LOOP_RC_PROCESSING will execute
   * "exit_action" (typically a "break" or "goto"), after updating "rc" to the
   * value the current statement should return.  If execution should continue,
   * LOOP_RC_PROCESSING will do nothing except reset "rc" to PLPGSQL_RC_OK.
   *
   * estate and rc are implicit arguments to the macro.
   * estate->exitlabel is examined and possibly updated.
   */
  #define LOOP_RC_PROCESSING(looplabel, exit_action) \
  	if (rc == PLPGSQL_RC_RETURN) \
  	{ \
  		/* RETURN, so propagate RC_RETURN out */ \
  		exit_action; \
  	} \
  	else if (rc == PLPGSQL_RC_EXIT) \
  	{ \
  		if (estate->exitlabel == NULL) \
  		{ \
  			/* unlabelled EXIT terminates this loop */ \
  			rc = PLPGSQL_RC_OK; \
  			exit_action; \
  		} \
  		else if ((looplabel) != NULL && \
  				 strcmp(looplabel, estate->exitlabel) == 0) \
  		{ \
  			/* labelled EXIT matching this loop, so terminate loop */ \
  			estate->exitlabel = NULL; \
  			rc = PLPGSQL_RC_OK; \
  			exit_action; \
  		} \
  		else \
  		{ \
  			/* non-matching labelled EXIT, propagate RC_EXIT out */ \
  			exit_action; \
  		} \
  	} \
  	else if (rc == PLPGSQL_RC_CONTINUE) \
  	{ \
  		if (estate->exitlabel == NULL) \
  		{ \
  			/* unlabelled CONTINUE matches this loop, so continue in loop */ \
  			rc = PLPGSQL_RC_OK; \
  		} \
  		else if ((looplabel) != NULL && \
  				 strcmp(looplabel, estate->exitlabel) == 0) \
  		{ \
  			/* labelled CONTINUE matching this loop, so continue in loop */ \
  			estate->exitlabel = NULL; \
  			rc = PLPGSQL_RC_OK; \
  		} \
  		else \
  		{ \
  			/* non-matching labelled CONTINUE, propagate RC_CONTINUE out */ \
  			exit_action; \
  		} \
  	} \
  	else \
  		Assert(rc == PLPGSQL_RC_OK)
  
  /************************************************************
   * Local function forward declarations
   ************************************************************/
  static void coerce_function_result_tuple(PLpgSQL_execstate *estate,
  										 TupleDesc tupdesc);
  static void plpgsql_exec_error_callback(void *arg);
  static void copy_plpgsql_datums(PLpgSQL_execstate *estate,
  								PLpgSQL_function *func);
  static void plpgsql_fulfill_promise(PLpgSQL_execstate *estate,
  									PLpgSQL_var *var);
  static MemoryContext get_stmt_mcontext(PLpgSQL_execstate *estate);
  static void push_stmt_mcontext(PLpgSQL_execstate *estate);
  static void pop_stmt_mcontext(PLpgSQL_execstate *estate);
  
  static int	exec_stmt_block(PLpgSQL_execstate *estate,
  							PLpgSQL_stmt_block *block);
  static int	exec_stmts(PLpgSQL_execstate *estate,
  					   List *stmts);
  static int	exec_stmt(PLpgSQL_execstate *estate,
  					  PLpgSQL_stmt *stmt);
  static int	exec_stmt_assign(PLpgSQL_execstate *estate,
  							 PLpgSQL_stmt_assign *stmt);
  static int	exec_stmt_perform(PLpgSQL_execstate *estate,
  							  PLpgSQL_stmt_perform *stmt);
  static int	exec_stmt_call(PLpgSQL_execstate *estate,
  						   PLpgSQL_stmt_call *stmt);
  static int	exec_stmt_getdiag(PLpgSQL_execstate *estate,
  							  PLpgSQL_stmt_getdiag *stmt);
  static int	exec_stmt_if(PLpgSQL_execstate *estate,
  						 PLpgSQL_stmt_if *stmt);
  static int	exec_stmt_case(PLpgSQL_execstate *estate,
  						   PLpgSQL_stmt_case *stmt);
  static int	exec_stmt_loop(PLpgSQL_execstate *estate,
  						   PLpgSQL_stmt_loop *stmt);
  static int	exec_stmt_while(PLpgSQL_execstate *estate,
  							PLpgSQL_stmt_while *stmt);
  static int	exec_stmt_fori(PLpgSQL_execstate *estate,
  						   PLpgSQL_stmt_fori *stmt);
  static int	exec_stmt_fors(PLpgSQL_execstate *estate,
  						   PLpgSQL_stmt_fors *stmt);
  static int	exec_stmt_forc(PLpgSQL_execstate *estate,
  						   PLpgSQL_stmt_forc *stmt);
  static int	exec_stmt_foreach_a(PLpgSQL_execstate *estate,
  								PLpgSQL_stmt_foreach_a *stmt);
  static int	exec_stmt_open(PLpgSQL_execstate *estate,
  						   PLpgSQL_stmt_open *stmt);
  static int	exec_stmt_fetch(PLpgSQL_execstate *estate,
  							PLpgSQL_stmt_fetch *stmt);
  static int	exec_stmt_close(PLpgSQL_execstate *estate,
  							PLpgSQL_stmt_close *stmt);
  static int	exec_stmt_exit(PLpgSQL_execstate *estate,
  						   PLpgSQL_stmt_exit *stmt);
  static int	exec_stmt_return(PLpgSQL_execstate *estate,
  							 PLpgSQL_stmt_return *stmt);
  static int	exec_stmt_return_next(PLpgSQL_execstate *estate,
  								  PLpgSQL_stmt_return_next *stmt);
  static int	exec_stmt_return_query(PLpgSQL_execstate *estate,
  								   PLpgSQL_stmt_return_query *stmt);
  static int	exec_stmt_raise(PLpgSQL_execstate *estate,
  							PLpgSQL_stmt_raise *stmt);
  static int	exec_stmt_assert(PLpgSQL_execstate *estate,
  							 PLpgSQL_stmt_assert *stmt);
  static int	exec_stmt_execsql(PLpgSQL_execstate *estate,
  							  PLpgSQL_stmt_execsql *stmt);
  static int	exec_stmt_dynexecute(PLpgSQL_execstate *estate,
  								 PLpgSQL_stmt_dynexecute *stmt);
  static int	exec_stmt_dynfors(PLpgSQL_execstate *estate,
  							  PLpgSQL_stmt_dynfors *stmt);
  static int	exec_stmt_commit(PLpgSQL_execstate *estate,
  							 PLpgSQL_stmt_commit *stmt);
  static int	exec_stmt_rollback(PLpgSQL_execstate *estate,
  							   PLpgSQL_stmt_rollback *stmt);
  static int	exec_stmt_set(PLpgSQL_execstate *estate,
  						  PLpgSQL_stmt_set *stmt);
  
  static void plpgsql_estate_setup(PLpgSQL_execstate *estate,
  								 PLpgSQL_function *func,
  								 ReturnSetInfo *rsi,
  								 EState *simple_eval_estate);
  static void exec_eval_cleanup(PLpgSQL_execstate *estate);
  
  static void exec_prepare_plan(PLpgSQL_execstate *estate,
  							  PLpgSQL_expr *expr, int cursorOptions,
  							  bool keepplan);
  static void exec_simple_check_plan(PLpgSQL_execstate *estate, PLpgSQL_expr *expr);
  static void exec_save_simple_expr(PLpgSQL_expr *expr, CachedPlan *cplan);
  static void exec_check_rw_parameter(PLpgSQL_expr *expr, int target_dno);
  static bool contains_target_param(Node *node, int *target_dno);
  static bool exec_eval_simple_expr(PLpgSQL_execstate *estate,
  								  PLpgSQL_expr *expr,
  								  Datum *result,
  								  bool *isNull,
  								  Oid *rettype,
  								  int32 *rettypmod);
  
  static void exec_assign_expr(PLpgSQL_execstate *estate,
  							 PLpgSQL_datum *target,
  							 PLpgSQL_expr *expr);
  static void exec_assign_c_string(PLpgSQL_execstate *estate,
  								 PLpgSQL_datum *target,
  								 const char *str);
  static void exec_assign_value(PLpgSQL_execstate *estate,
  							  PLpgSQL_datum *target,
  							  Datum value, bool isNull,
  							  Oid valtype, int32 valtypmod);
  static void exec_eval_datum(PLpgSQL_execstate *estate,
  							PLpgSQL_datum *datum,
  							Oid *typeid,
  							int32 *typetypmod,
  							Datum *value,
  							bool *isnull);
  static int	exec_eval_integer(PLpgSQL_execstate *estate,
  							  PLpgSQL_expr *expr,
  							  bool *isNull);
  static bool exec_eval_boolean(PLpgSQL_execstate *estate,
  							  PLpgSQL_expr *expr,
  							  bool *isNull);
  static Datum exec_eval_expr(PLpgSQL_execstate *estate,
  							PLpgSQL_expr *expr,
  							bool *isNull,
  							Oid *rettype,
  							int32 *rettypmod);
  static int	exec_run_select(PLpgSQL_execstate *estate,
  							PLpgSQL_expr *expr, long maxtuples, Portal *portalP);
  static int	exec_for_query(PLpgSQL_execstate *estate, PLpgSQL_stmt_forq *stmt,
  						   Portal portal, bool prefetch_ok);
  static ParamListInfo setup_param_list(PLpgSQL_execstate *estate,
  									  PLpgSQL_expr *expr);
  static ParamExternData *plpgsql_param_fetch(ParamListInfo params,
  											int paramid, bool speculative,
  											ParamExternData *workspace);
  static void plpgsql_param_compile(ParamListInfo params, Param *param,
  								  ExprState *state,
  								  Datum *resv, bool *resnull);
  static void plpgsql_param_eval_var(ExprState *state, ExprEvalStep *op,
  								   ExprContext *econtext);
  static void plpgsql_param_eval_var_ro(ExprState *state, ExprEvalStep *op,
  									  ExprContext *econtext);
  static void plpgsql_param_eval_recfield(ExprState *state, ExprEvalStep *op,
  										ExprContext *econtext);
  static void plpgsql_param_eval_generic(ExprState *state, ExprEvalStep *op,
  									   ExprContext *econtext);
  static void plpgsql_param_eval_generic_ro(ExprState *state, ExprEvalStep *op,
  										  ExprContext *econtext);
  static void exec_move_row(PLpgSQL_execstate *estate,
  						  PLpgSQL_variable *target,
  						  HeapTuple tup, TupleDesc tupdesc);
  static void revalidate_rectypeid(PLpgSQL_rec *rec);
  static ExpandedRecordHeader *make_expanded_record_for_rec(PLpgSQL_execstate *estate,
  														  PLpgSQL_rec *rec,
  														  TupleDesc srctupdesc,
  														  ExpandedRecordHeader *srcerh);
  static void exec_move_row_from_fields(PLpgSQL_execstate *estate,
  									  PLpgSQL_variable *target,
  									  ExpandedRecordHeader *newerh,
  									  Datum *values, bool *nulls,
  									  TupleDesc tupdesc);
  static bool compatible_tupdescs(TupleDesc src_tupdesc, TupleDesc dst_tupdesc);
  static HeapTuple make_tuple_from_row(PLpgSQL_execstate *estate,
  									 PLpgSQL_row *row,
  									 TupleDesc tupdesc);
  static TupleDesc deconstruct_composite_datum(Datum value,
  											 HeapTupleData *tmptup);
  static void exec_move_row_from_datum(PLpgSQL_execstate *estate,
  									 PLpgSQL_variable *target,
  									 Datum value);
  static void instantiate_empty_record_variable(PLpgSQL_execstate *estate,
  											  PLpgSQL_rec *rec);
  static char *convert_value_to_string(PLpgSQL_execstate *estate,
  									 Datum value, Oid valtype);
  static Datum exec_cast_value(PLpgSQL_execstate *estate,
  							 Datum value, bool *isnull,
  							 Oid valtype, int32 valtypmod,
  							 Oid reqtype, int32 reqtypmod);
  static plpgsql_CastHashEntry *get_cast_hashentry(PLpgSQL_execstate *estate,
  												 Oid srctype, int32 srctypmod,
  												 Oid dsttype, int32 dsttypmod);
  static void exec_init_tuple_store(PLpgSQL_execstate *estate);
  static void exec_set_found(PLpgSQL_execstate *estate, bool state);
  static void plpgsql_create_econtext(PLpgSQL_execstate *estate);
  static void plpgsql_destroy_econtext(PLpgSQL_execstate *estate);
  static void assign_simple_var(PLpgSQL_execstate *estate, PLpgSQL_var *var,
  							  Datum newvalue, bool isnull, bool freeable);
  static void assign_text_var(PLpgSQL_execstate *estate, PLpgSQL_var *var,
  							const char *str);
  static void assign_record_var(PLpgSQL_execstate *estate, PLpgSQL_rec *rec,
  							  ExpandedRecordHeader *erh);
  static PreparedParamsData *exec_eval_using_params(PLpgSQL_execstate *estate,
  												  List *params);
  static Portal exec_dynquery_with_params(PLpgSQL_execstate *estate,
  										PLpgSQL_expr *dynquery, List *params,
  										const char *portalname, int cursorOptions);
  static char *format_expr_params(PLpgSQL_execstate *estate,
  								const PLpgSQL_expr *expr);
  static char *format_preparedparamsdata(PLpgSQL_execstate *estate,
  									   const PreparedParamsData *ppd);
  
  
  /* ----------
   * plpgsql_exec_function	Called by the call handler for
   *				function execution.
   *
   * This is also used to execute inline code blocks (DO blocks).  The only
   * difference that this code is aware of is that for a DO block, we want
   * to use a private simple_eval_estate, which is created and passed in by
   * the caller.  For regular functions, pass NULL, which implies using
   * shared_simple_eval_estate.  (When using a private simple_eval_estate,
   * we must also use a private cast hashtable, but that's taken care of
   * within plpgsql_estate_setup.)
   * ----------
   */
  Datum
  plpgsql_exec_function(PLpgSQL_function *func, FunctionCallInfo fcinfo,
  					  EState *simple_eval_estate, bool atomic)
  {
  	PLpgSQL_execstate estate;
  	ErrorContextCallback plerrcontext;
  	int			i;
  	int			rc;
  
  	/*
  	 * Setup the execution state
  	 */
  	plpgsql_estate_setup(&estate, func, (ReturnSetInfo *) fcinfo->resultinfo,
  						 simple_eval_estate);
  	estate.atomic = atomic;
  
  	/*
  	 * Setup error traceback support for ereport()
  	 */
  	plerrcontext.callback = plpgsql_exec_error_callback;
  	plerrcontext.arg = &estate;
  	plerrcontext.previous = error_context_stack;
  	error_context_stack = &plerrcontext;
  
  	/*
  	 * Make local execution copies of all the datums
  	 */
  	estate.err_text = gettext_noop("during initialization of execution state");
  	copy_plpgsql_datums(&estate, func);
  
  	/*
  	 * Store the actual call argument values into the appropriate variables
  	 */
  	estate.err_text = gettext_noop("while storing call arguments into local variables");
  	for (i = 0; i < func->fn_nargs; i++)
  	{
  		int			n = func->fn_argvarnos[i];
  
  		switch (estate.datums[n]->dtype)
  		{
  			case PLPGSQL_DTYPE_VAR:
  				{
  					PLpgSQL_var *var = (PLpgSQL_var *) estate.datums[n];
  
  					assign_simple_var(&estate, var,
  									  fcinfo->args[i].value,
  									  fcinfo->args[i].isnull,
  									  false);
  
  					/*
  					 * Force any array-valued parameter to be stored in
  					 * expanded form in our local variable, in hopes of
  					 * improving efficiency of uses of the variable.  (This is
  					 * a hack, really: why only arrays? Need more thought
  					 * about which cases are likely to win.  See also
  					 * typisarray-specific heuristic in exec_assign_value.)
  					 *
  					 * Special cases: If passed a R/W expanded pointer, assume
  					 * we can commandeer the object rather than having to copy
  					 * it.  If passed a R/O expanded pointer, just keep it as
  					 * the value of the variable for the moment.  (We'll force
  					 * it to R/W if the variable gets modified, but that may
  					 * very well never happen.)
  					 */
  					if (!var->isnull && var->datatype->typisarray)
  					{
  						if (VARATT_IS_EXTERNAL_EXPANDED_RW(DatumGetPointer(var->value)))
  						{
  							/* take ownership of R/W object */
  							assign_simple_var(&estate, var,
  											  TransferExpandedObject(var->value,
  																	 estate.datum_context),
  											  false,
  											  true);
  						}
  						else if (VARATT_IS_EXTERNAL_EXPANDED_RO(DatumGetPointer(var->value)))
  						{
  							/* R/O pointer, keep it as-is until assigned to */
  						}
  						else
  						{
  							/* flat array, so force to expanded form */
  							assign_simple_var(&estate, var,
  											  expand_array(var->value,
  														   estate.datum_context,
  														   NULL),
  											  false,
  											  true);
  						}
  					}
  				}
  				break;
  
  			case PLPGSQL_DTYPE_REC:
  				{
  					PLpgSQL_rec *rec = (PLpgSQL_rec *) estate.datums[n];
  
  					if (!fcinfo->args[i].isnull)
  					{
  						/* Assign row value from composite datum */
  						exec_move_row_from_datum(&estate,
  												 (PLpgSQL_variable *) rec,
  												 fcinfo->args[i].value);
  					}
  					else
  					{
  						/* If arg is null, set variable to null */
  						exec_move_row(&estate, (PLpgSQL_variable *) rec,
  									  NULL, NULL);
  					}
  					/* clean up after exec_move_row() */
  					exec_eval_cleanup(&estate);
  				}
  				break;
  
  			default:
  				/* Anything else should not be an argument variable */
  				elog(ERROR, "unrecognized dtype: %d", func->datums[i]->dtype);
  		}
  	}
  
  	estate.err_text = gettext_noop("during function entry");
  
  	/*
  	 * Set the magic variable FOUND to false
  	 */
  	exec_set_found(&estate, false);
  
  	/*
  	 * Let the instrumentation plugin peek at this function
  	 */
  	if (*plpgsql_plugin_ptr && (*plpgsql_plugin_ptr)->func_beg)
  		((*plpgsql_plugin_ptr)->func_beg) (&estate, func);
  
  	/*
  	 * Now call the toplevel block of statements
  	 */
  	estate.err_text = NULL;
  	estate.err_stmt = (PLpgSQL_stmt *) (func->action);
  	rc = exec_stmt(&estate, (PLpgSQL_stmt *) func->action);
  	if (rc != PLPGSQL_RC_RETURN)
  	{
  		estate.err_stmt = NULL;
  		estate.err_text = NULL;
  		ereport(ERROR,
  				(errcode(ERRCODE_S_R_E_FUNCTION_EXECUTED_NO_RETURN_STATEMENT),
  				 errmsg("control reached end of function without RETURN")));
  	}
  
  	/*
  	 * We got a return value - process it
  	 */
  	estate.err_stmt = NULL;
  	estate.err_text = gettext_noop("while casting return value to function's return type");
  
  	fcinfo->isnull = estate.retisnull;
  
  	if (estate.retisset)
  	{
  		ReturnSetInfo *rsi = estate.rsi;
  
  		/* Check caller can handle a set result */
  		if (!rsi || !IsA(rsi, ReturnSetInfo) ||
  			(rsi->allowedModes & SFRM_Materialize) == 0)
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("set-valued function called in context that cannot accept a set")));
  		rsi->returnMode = SFRM_Materialize;
  
  		/* If we produced any tuples, send back the result */
  		if (estate.tuple_store)
  		{
  			MemoryContext oldcxt;
  
  			rsi->setResult = estate.tuple_store;
  			oldcxt = MemoryContextSwitchTo(estate.tuple_store_cxt);
  			rsi->setDesc = CreateTupleDescCopy(estate.tuple_store_desc);
  			MemoryContextSwitchTo(oldcxt);
  		}
  		estate.retval = (Datum) 0;
  		fcinfo->isnull = true;
  	}
  	else if (!estate.retisnull)
  	{
  		/*
  		 * Cast result value to function's declared result type, and copy it
  		 * out to the upper executor memory context.  We must treat tuple
  		 * results specially in order to deal with cases like rowtypes
  		 * involving dropped columns.
  		 */
  		if (estate.retistuple)
  		{
  			/* Don't need coercion if rowtype is known to match */
  			if (func->fn_rettype == estate.rettype &&
  				func->fn_rettype != RECORDOID)
  			{
  				/*
  				 * Copy the tuple result into upper executor memory context.
  				 * However, if we have a R/W expanded datum, we can just
  				 * transfer its ownership out to the upper context.
  				 */
  				estate.retval = SPI_datumTransfer(estate.retval,
  												  false,
  												  -1);
  			}
  			else
  			{
  				/*
  				 * Need to look up the expected result type.  XXX would be
  				 * better to cache the tupdesc instead of repeating
  				 * get_call_result_type(), but the only easy place to save it
  				 * is in the PLpgSQL_function struct, and that's too
  				 * long-lived: composite types could change during the
  				 * existence of a PLpgSQL_function.
  				 */
  				Oid			resultTypeId;
  				TupleDesc	tupdesc;
  
  				switch (get_call_result_type(fcinfo, &resultTypeId, &tupdesc))
  				{
  					case TYPEFUNC_COMPOSITE:
  						/* got the expected result rowtype, now coerce it */
  						coerce_function_result_tuple(&estate, tupdesc);
  						break;
  					case TYPEFUNC_COMPOSITE_DOMAIN:
  						/* got the expected result rowtype, now coerce it */
  						coerce_function_result_tuple(&estate, tupdesc);
  						/* and check domain constraints */
  						/* XXX allowing caching here would be good, too */
  						domain_check(estate.retval, false, resultTypeId,
  									 NULL, NULL);
  						break;
  					case TYPEFUNC_RECORD:
  
  						/*
  						 * Failed to determine actual type of RECORD.  We
  						 * could raise an error here, but what this means in
  						 * practice is that the caller is expecting any old
  						 * generic rowtype, so we don't really need to be
  						 * restrictive.  Pass back the generated result as-is.
  						 */
  						estate.retval = SPI_datumTransfer(estate.retval,
  														  false,
  														  -1);
  						break;
  					default:
  						/* shouldn't get here if retistuple is true ... */
  						elog(ERROR, "return type must be a row type");
  						break;
  				}
  			}
  		}
  		else
  		{
  			/* Scalar case: use exec_cast_value */
  			estate.retval = exec_cast_value(&estate,
  											estate.retval,
  											&fcinfo->isnull,
  											estate.rettype,
  											-1,
  											func->fn_rettype,
  											-1);
  
  			/*
  			 * If the function's return type isn't by value, copy the value
  			 * into upper executor memory context.  However, if we have a R/W
  			 * expanded datum, we can just transfer its ownership out to the
  			 * upper executor context.
  			 */
  			if (!fcinfo->isnull && !func->fn_retbyval)
  				estate.retval = SPI_datumTransfer(estate.retval,
  												  false,
  												  func->fn_rettyplen);
  		}
  	}
  	else
  	{
  		/*
  		 * We're returning a NULL, which normally requires no conversion work
  		 * regardless of datatypes.  But, if we are casting it to a domain
  		 * return type, we'd better check that the domain's constraints pass.
  		 */
  		if (func->fn_retisdomain)
  			estate.retval = exec_cast_value(&estate,
  											estate.retval,
  											&fcinfo->isnull,
  											estate.rettype,
  											-1,
  											func->fn_rettype,
  											-1);
  	}
  
  	estate.err_text = gettext_noop("during function exit");
  
  	/*
  	 * Let the instrumentation plugin peek at this function
  	 */
  	if (*plpgsql_plugin_ptr && (*plpgsql_plugin_ptr)->func_end)
  		((*plpgsql_plugin_ptr)->func_end) (&estate, func);
  
  	/* Clean up any leftover temporary memory */
  	plpgsql_destroy_econtext(&estate);
  	exec_eval_cleanup(&estate);
  	/* stmt_mcontext will be destroyed when function's main context is */
  
  	/*
  	 * Pop the error context stack
  	 */
  	error_context_stack = plerrcontext.previous;
  
  	/*
  	 * Return the function's result
  	 */
  	return estate.retval;
  }
  
  /*
   * Helper for plpgsql_exec_function: coerce composite result to the specified
   * tuple descriptor, and copy it out to upper executor memory.  This is split
   * out mostly for cosmetic reasons --- the logic would be very deeply nested
   * otherwise.
   *
   * estate->retval is updated in-place.
   */
  static void
  coerce_function_result_tuple(PLpgSQL_execstate *estate, TupleDesc tupdesc)
  {
  	HeapTuple	rettup;
  	TupleDesc	retdesc;
  	TupleConversionMap *tupmap;
  
  	/* We assume exec_stmt_return verified that result is composite */
  	Assert(type_is_rowtype(estate->rettype));
  
  	/* We can special-case expanded records for speed */
  	if (VARATT_IS_EXTERNAL_EXPANDED(DatumGetPointer(estate->retval)))
  	{
  		ExpandedRecordHeader *erh = (ExpandedRecordHeader *) DatumGetEOHP(estate->retval);
  
  		Assert(erh->er_magic == ER_MAGIC);
  
  		/* Extract record's TupleDesc */
  		retdesc = expanded_record_get_tupdesc(erh);
  
  		/* check rowtype compatibility */
  		tupmap = convert_tuples_by_position(retdesc,
  											tupdesc,
  											gettext_noop("returned record type does not match expected record type"));
  
  		/* it might need conversion */
  		if (tupmap)
  		{
  			rettup = expanded_record_get_tuple(erh);
  			Assert(rettup);
  			rettup = execute_attr_map_tuple(rettup, tupmap);
  
  			/*
  			 * Copy tuple to upper executor memory, as a tuple Datum.  Make
  			 * sure it is labeled with the caller-supplied tuple type.
  			 */
  			estate->retval = PointerGetDatum(SPI_returntuple(rettup, tupdesc));
  			/* no need to free map, we're about to return anyway */
  		}
  		else if (!(tupdesc->tdtypeid == erh->er_decltypeid ||
  				   (tupdesc->tdtypeid == RECORDOID &&
  					!ExpandedRecordIsDomain(erh))))
  		{
  			/*
  			 * The expanded record has the right physical tupdesc, but the
  			 * wrong type ID.  (Typically, the expanded record is RECORDOID
  			 * but the function is declared to return a named composite type.
  			 * As in exec_move_row_from_datum, we don't allow returning a
  			 * composite-domain record from a function declared to return
  			 * RECORD.)  So we must flatten the record to a tuple datum and
  			 * overwrite its type fields with the right thing.  spi.c doesn't
  			 * provide any easy way to deal with this case, so we end up
  			 * duplicating the guts of datumCopy() :-(
  			 */
  			Size		resultsize;
  			HeapTupleHeader tuphdr;
  
  			resultsize = EOH_get_flat_size(&erh->hdr);
  			tuphdr = (HeapTupleHeader) SPI_palloc(resultsize);
  			EOH_flatten_into(&erh->hdr, (void *) tuphdr, resultsize);
  			HeapTupleHeaderSetTypeId(tuphdr, tupdesc->tdtypeid);
  			HeapTupleHeaderSetTypMod(tuphdr, tupdesc->tdtypmod);
  			estate->retval = PointerGetDatum(tuphdr);
  		}
  		else
  		{
  			/*
  			 * We need only copy result into upper executor memory context.
  			 * However, if we have a R/W expanded datum, we can just transfer
  			 * its ownership out to the upper executor context.
  			 */
  			estate->retval = SPI_datumTransfer(estate->retval,
  											   false,
  											   -1);
  		}
  	}
  	else
  	{
  		/* Convert composite datum to a HeapTuple and TupleDesc */
  		HeapTupleData tmptup;
  
  		retdesc = deconstruct_composite_datum(estate->retval, &tmptup);
  		rettup = &tmptup;
  
  		/* check rowtype compatibility */
  		tupmap = convert_tuples_by_position(retdesc,
  											tupdesc,
  											gettext_noop("returned record type does not match expected record type"));
  
  		/* it might need conversion */
  		if (tupmap)
  			rettup = execute_attr_map_tuple(rettup, tupmap);
  
  		/*
  		 * Copy tuple to upper executor memory, as a tuple Datum.  Make sure
  		 * it is labeled with the caller-supplied tuple type.
  		 */
  		estate->retval = PointerGetDatum(SPI_returntuple(rettup, tupdesc));
  
  		/* no need to free map, we're about to return anyway */
  
  		ReleaseTupleDesc(retdesc);
  	}
  }
  
  
  /* ----------
   * plpgsql_exec_trigger		Called by the call handler for
   *				trigger execution.
   * ----------
   */
  HeapTuple
  plpgsql_exec_trigger(PLpgSQL_function *func,
  					 TriggerData *trigdata)
  {
  	PLpgSQL_execstate estate;
  	ErrorContextCallback plerrcontext;
  	int			rc;
  	TupleDesc	tupdesc;
  	PLpgSQL_rec *rec_new,
  			   *rec_old;
  	HeapTuple	rettup;
  
  	/*
  	 * Setup the execution state
  	 */
  	plpgsql_estate_setup(&estate, func, NULL, NULL);
  	estate.trigdata = trigdata;
  
  	/*
  	 * Setup error traceback support for ereport()
  	 */
  	plerrcontext.callback = plpgsql_exec_error_callback;
  	plerrcontext.arg = &estate;
  	plerrcontext.previous = error_context_stack;
  	error_context_stack = &plerrcontext;
  
  	/*
  	 * Make local execution copies of all the datums
  	 */
  	estate.err_text = gettext_noop("during initialization of execution state");
  	copy_plpgsql_datums(&estate, func);
  
  	/*
  	 * Put the OLD and NEW tuples into record variables
  	 *
  	 * We set up expanded records for both variables even though only one may
  	 * have a value.  This allows record references to succeed in functions
  	 * that are used for multiple trigger types.  For example, we might have a
  	 * test like "if (TG_OP = 'INSERT' and NEW.foo = 'xyz')", which should
  	 * work regardless of the current trigger type.  If a value is actually
  	 * fetched from an unsupplied tuple, it will read as NULL.
  	 */
  	tupdesc = RelationGetDescr(trigdata->tg_relation);
  
  	rec_new = (PLpgSQL_rec *) (estate.datums[func->new_varno]);
  	rec_old = (PLpgSQL_rec *) (estate.datums[func->old_varno]);
  
  	rec_new->erh = make_expanded_record_from_tupdesc(tupdesc,
  													 estate.datum_context);
  	rec_old->erh = make_expanded_record_from_exprecord(rec_new->erh,
  													   estate.datum_context);
  
  	if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
  	{
  		/*
  		 * Per-statement triggers don't use OLD/NEW variables
  		 */
  	}
  	else if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
  	{
  		expanded_record_set_tuple(rec_new->erh, trigdata->tg_trigtuple,
  								  false, false);
  	}
  	else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
  	{
  		expanded_record_set_tuple(rec_new->erh, trigdata->tg_newtuple,
  								  false, false);
  		expanded_record_set_tuple(rec_old->erh, trigdata->tg_trigtuple,
  								  false, false);
  
  		/*
  		 * In BEFORE trigger, stored generated columns are not computed yet,
  		 * so make them null in the NEW row.  (Only needed in UPDATE branch;
  		 * in the INSERT case, they are already null, but in UPDATE, the field
  		 * still contains the old value.)  Alternatively, we could construct a
  		 * whole new row structure without the generated columns, but this way
  		 * seems more efficient and potentially less confusing.
  		 */
  		if (tupdesc->constr && tupdesc->constr->has_generated_stored &&
  			TRIGGER_FIRED_BEFORE(trigdata->tg_event))
  		{
  			for (int i = 0; i < tupdesc->natts; i++)
  				if (TupleDescAttr(tupdesc, i)->attgenerated == ATTRIBUTE_GENERATED_STORED)
  					expanded_record_set_field_internal(rec_new->erh,
  													   i + 1,
  													   (Datum) 0,
  													   true,	/* isnull */
  													   false, false);
  		}
  	}
  	else if (TRIGGER_FIRED_BY_DELETE(trigdata->tg_event))
  	{
  		expanded_record_set_tuple(rec_old->erh, trigdata->tg_trigtuple,
  								  false, false);
  	}
  	else
  		elog(ERROR, "unrecognized trigger action: not INSERT, DELETE, or UPDATE");
  
  	/* Make transition tables visible to this SPI connection */
  	rc = SPI_register_trigger_data(trigdata);
  	Assert(rc >= 0);
  
  	estate.err_text = gettext_noop("during function entry");
  
  	/*
  	 * Set the magic variable FOUND to false
  	 */
  	exec_set_found(&estate, false);
  
  	/*
  	 * Let the instrumentation plugin peek at this function
  	 */
  	if (*plpgsql_plugin_ptr && (*plpgsql_plugin_ptr)->func_beg)
  		((*plpgsql_plugin_ptr)->func_beg) (&estate, func);
  
  	/*
  	 * Now call the toplevel block of statements
  	 */
  	estate.err_text = NULL;
  	estate.err_stmt = (PLpgSQL_stmt *) (func->action);
  	rc = exec_stmt(&estate, (PLpgSQL_stmt *) func->action);
  	if (rc != PLPGSQL_RC_RETURN)
  	{
  		estate.err_stmt = NULL;
  		estate.err_text = NULL;
  		ereport(ERROR,
  				(errcode(ERRCODE_S_R_E_FUNCTION_EXECUTED_NO_RETURN_STATEMENT),
  				 errmsg("control reached end of trigger procedure without RETURN")));
  	}
  
  	estate.err_stmt = NULL;
  	estate.err_text = gettext_noop("during function exit");
  
  	if (estate.retisset)
  		ereport(ERROR,
  				(errcode(ERRCODE_DATATYPE_MISMATCH),
  				 errmsg("trigger procedure cannot return a set")));
  
  	/*
  	 * Check that the returned tuple structure has the same attributes, the
  	 * relation that fired the trigger has. A per-statement trigger always
  	 * needs to return NULL, so we ignore any return value the function itself
  	 * produces (XXX: is this a good idea?)
  	 *
  	 * XXX This way it is possible, that the trigger returns a tuple where
  	 * attributes don't have the correct atttypmod's length. It's up to the
  	 * trigger's programmer to ensure that this doesn't happen. Jan
  	 */
  	if (estate.retisnull || !TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
  		rettup = NULL;
  	else
  	{
  		TupleDesc	retdesc;
  		TupleConversionMap *tupmap;
  
  		/* We assume exec_stmt_return verified that result is composite */
  		Assert(type_is_rowtype(estate.rettype));
  
  		/* We can special-case expanded records for speed */
  		if (VARATT_IS_EXTERNAL_EXPANDED(DatumGetPointer(estate.retval)))
  		{
  			ExpandedRecordHeader *erh = (ExpandedRecordHeader *) DatumGetEOHP(estate.retval);
  
  			Assert(erh->er_magic == ER_MAGIC);
  
  			/* Extract HeapTuple and TupleDesc */
  			rettup = expanded_record_get_tuple(erh);
  			Assert(rettup);
  			retdesc = expanded_record_get_tupdesc(erh);
  
  			if (retdesc != RelationGetDescr(trigdata->tg_relation))
  			{
  				/* check rowtype compatibility */
  				tupmap = convert_tuples_by_position(retdesc,
  													RelationGetDescr(trigdata->tg_relation),
  													gettext_noop("returned row structure does not match the structure of the triggering table"));
  				/* it might need conversion */
  				if (tupmap)
  					rettup = execute_attr_map_tuple(rettup, tupmap);
  				/* no need to free map, we're about to return anyway */
  			}
  
  			/*
  			 * Copy tuple to upper executor memory.  But if user just did
  			 * "return new" or "return old" without changing anything, there's
  			 * no need to copy; we can return the original tuple (which will
  			 * save a few cycles in trigger.c as well as here).
  			 */
  			if (rettup != trigdata->tg_newtuple &&
  				rettup != trigdata->tg_trigtuple)
  				rettup = SPI_copytuple(rettup);
  		}
  		else
  		{
  			/* Convert composite datum to a HeapTuple and TupleDesc */
  			HeapTupleData tmptup;
  
  			retdesc = deconstruct_composite_datum(estate.retval, &tmptup);
  			rettup = &tmptup;
  
  			/* check rowtype compatibility */
  			tupmap = convert_tuples_by_position(retdesc,
  												RelationGetDescr(trigdata->tg_relation),
  												gettext_noop("returned row structure does not match the structure of the triggering table"));
  			/* it might need conversion */
  			if (tupmap)
  				rettup = execute_attr_map_tuple(rettup, tupmap);
  
  			ReleaseTupleDesc(retdesc);
  			/* no need to free map, we're about to return anyway */
  
  			/* Copy tuple to upper executor memory */
  			rettup = SPI_copytuple(rettup);
  		}
  	}
  
  	/*
  	 * Let the instrumentation plugin peek at this function
  	 */
  	if (*plpgsql_plugin_ptr && (*plpgsql_plugin_ptr)->func_end)
  		((*plpgsql_plugin_ptr)->func_end) (&estate, func);
  
  	/* Clean up any leftover temporary memory */
  	plpgsql_destroy_econtext(&estate);
  	exec_eval_cleanup(&estate);
  	/* stmt_mcontext will be destroyed when function's main context is */
  
  	/*
  	 * Pop the error context stack
  	 */
  	error_context_stack = plerrcontext.previous;
  
  	/*
  	 * Return the trigger's result
  	 */
  	return rettup;
  }
  
  /* ----------
   * plpgsql_exec_event_trigger		Called by the call handler for
   *				event trigger execution.
   * ----------
   */
  void
  plpgsql_exec_event_trigger(PLpgSQL_function *func, EventTriggerData *trigdata)
  {
  	PLpgSQL_execstate estate;
  	ErrorContextCallback plerrcontext;
  	int			rc;
  
  	/*
  	 * Setup the execution state
  	 */
  	plpgsql_estate_setup(&estate, func, NULL, NULL);
  	estate.evtrigdata = trigdata;
  
  	/*
  	 * Setup error traceback support for ereport()
  	 */
  	plerrcontext.callback = plpgsql_exec_error_callback;
  	plerrcontext.arg = &estate;
  	plerrcontext.previous = error_context_stack;
  	error_context_stack = &plerrcontext;
  
  	/*
  	 * Make local execution copies of all the datums
  	 */
  	estate.err_text = gettext_noop("during initialization of execution state");
  	copy_plpgsql_datums(&estate, func);
  
  	/*
  	 * Let the instrumentation plugin peek at this function
  	 */
  	if (*plpgsql_plugin_ptr && (*plpgsql_plugin_ptr)->func_beg)
  		((*plpgsql_plugin_ptr)->func_beg) (&estate, func);
  
  	/*
  	 * Now call the toplevel block of statements
  	 */
  	estate.err_text = NULL;
  	estate.err_stmt = (PLpgSQL_stmt *) (func->action);
  	rc = exec_stmt(&estate, (PLpgSQL_stmt *) func->action);
  	if (rc != PLPGSQL_RC_RETURN)
  	{
  		estate.err_stmt = NULL;
  		estate.err_text = NULL;
  		ereport(ERROR,
  				(errcode(ERRCODE_S_R_E_FUNCTION_EXECUTED_NO_RETURN_STATEMENT),
  				 errmsg("control reached end of trigger procedure without RETURN")));
  	}
  
  	estate.err_stmt = NULL;
  	estate.err_text = gettext_noop("during function exit");
  
  	/*
  	 * Let the instrumentation plugin peek at this function
  	 */
  	if (*plpgsql_plugin_ptr && (*plpgsql_plugin_ptr)->func_end)
  		((*plpgsql_plugin_ptr)->func_end) (&estate, func);
  
  	/* Clean up any leftover temporary memory */
  	plpgsql_destroy_econtext(&estate);
  	exec_eval_cleanup(&estate);
  	/* stmt_mcontext will be destroyed when function's main context is */
  
  	/*
  	 * Pop the error context stack
  	 */
  	error_context_stack = plerrcontext.previous;
  }
  
  /*
   * error context callback to let us supply a call-stack traceback
   */
  static void
  plpgsql_exec_error_callback(void *arg)
  {
  	PLpgSQL_execstate *estate = (PLpgSQL_execstate *) arg;
  
  	if (estate->err_text != NULL)
  	{
  		/*
  		 * We don't expend the cycles to run gettext() on err_text unless we
  		 * actually need it.  Therefore, places that set up err_text should
  		 * use gettext_noop() to ensure the strings get recorded in the
  		 * message dictionary.
  		 *
  		 * If both err_text and err_stmt are set, use the err_text as
  		 * description, but report the err_stmt's line number.  When err_stmt
  		 * is not set, we're in function entry/exit, or some such place not
  		 * attached to a specific line number.
  		 */
  		if (estate->err_stmt != NULL)
  		{
  			/*
  			 * translator: last %s is a phrase such as "during statement block
  			 * local variable initialization"
  			 */
  			errcontext("PL/pgSQL function %s line %d %s",
  					   estate->func->fn_signature,
  					   estate->err_stmt->lineno,
  					   _(estate->err_text));
  		}
  		else
  		{
  			/*
  			 * translator: last %s is a phrase such as "while storing call
  			 * arguments into local variables"
  			 */
  			errcontext("PL/pgSQL function %s %s",
  					   estate->func->fn_signature,
  					   _(estate->err_text));
  		}
  	}
  	else if (estate->err_stmt != NULL)
  	{
  		/* translator: last %s is a plpgsql statement type name */
  		errcontext("PL/pgSQL function %s line %d at %s",
  				   estate->func->fn_signature,
  				   estate->err_stmt->lineno,
  				   plpgsql_stmt_typename(estate->err_stmt));
  	}
  	else
  		errcontext("PL/pgSQL function %s",
  				   estate->func->fn_signature);
  }
  
  
  /* ----------
   * Support function for initializing local execution variables
   * ----------
   */
  static void
  copy_plpgsql_datums(PLpgSQL_execstate *estate,
  					PLpgSQL_function *func)
  {
  	int			ndatums = estate->ndatums;
  	PLpgSQL_datum **indatums;
  	PLpgSQL_datum **outdatums;
  	char	   *workspace;
  	char	   *ws_next;
  	int			i;
  
  	/* Allocate local datum-pointer array */
  	estate->datums = (PLpgSQL_datum **)
  		palloc(sizeof(PLpgSQL_datum *) * ndatums);
  
  	/*
  	 * To reduce palloc overhead, we make a single palloc request for all the
  	 * space needed for locally-instantiated datums.
  	 */
  	workspace = palloc(func->copiable_size);
  	ws_next = workspace;
  
  	/* Fill datum-pointer array, copying datums into workspace as needed */
  	indatums = func->datums;
  	outdatums = estate->datums;
  	for (i = 0; i < ndatums; i++)
  	{
  		PLpgSQL_datum *indatum = indatums[i];
  		PLpgSQL_datum *outdatum;
  
  		/* This must agree with plpgsql_finish_datums on what is copiable */
  		switch (indatum->dtype)
  		{
  			case PLPGSQL_DTYPE_VAR:
  			case PLPGSQL_DTYPE_PROMISE:
  				outdatum = (PLpgSQL_datum *) ws_next;
  				memcpy(outdatum, indatum, sizeof(PLpgSQL_var));
  				ws_next += MAXALIGN(sizeof(PLpgSQL_var));
  				break;
  
  			case PLPGSQL_DTYPE_REC:
  				outdatum = (PLpgSQL_datum *) ws_next;
  				memcpy(outdatum, indatum, sizeof(PLpgSQL_rec));
  				ws_next += MAXALIGN(sizeof(PLpgSQL_rec));
  				break;
  
  			case PLPGSQL_DTYPE_ROW:
  			case PLPGSQL_DTYPE_RECFIELD:
  			case PLPGSQL_DTYPE_ARRAYELEM:
  
  				/*
  				 * These datum records are read-only at runtime, so no need to
  				 * copy them (well, RECFIELD and ARRAYELEM contain cached
  				 * data, but we'd just as soon centralize the caching anyway).
  				 */
  				outdatum = indatum;
  				break;
  
  			default:
  				elog(ERROR, "unrecognized dtype: %d", indatum->dtype);
  				outdatum = NULL;	/* keep compiler quiet */
  				break;
  		}
  
  		outdatums[i] = outdatum;
  	}
  
  	Assert(ws_next == workspace + func->copiable_size);
  }
  
  /*
   * If the variable has an armed "promise", compute the promised value
   * and assign it to the variable.
   * The assignment automatically disarms the promise.
   */
  static void
  plpgsql_fulfill_promise(PLpgSQL_execstate *estate,
  						PLpgSQL_var *var)
  {
  	MemoryContext oldcontext;
  
  	if (var->promise == PLPGSQL_PROMISE_NONE)
  		return;					/* nothing to do */
  
  	/*
  	 * This will typically be invoked in a short-lived context such as the
  	 * mcontext.  We must create variable values in the estate's datum
  	 * context.  This quick-and-dirty solution risks leaking some additional
  	 * cruft there, but since any one promise is honored at most once per
  	 * function call, it's probably not worth being more careful.
  	 */
  	oldcontext = MemoryContextSwitchTo(estate->datum_context);
  
  	switch (var->promise)
  	{
  		case PLPGSQL_PROMISE_TG_NAME:
  			if (estate->trigdata == NULL)
  				elog(ERROR, "trigger promise is not in a trigger function");
  			assign_simple_var(estate, var,
  							  DirectFunctionCall1(namein,
  												  CStringGetDatum(estate->trigdata->tg_trigger->tgname)),
  							  false, true);
  			break;
  
  		case PLPGSQL_PROMISE_TG_WHEN:
  			if (estate->trigdata == NULL)
  				elog(ERROR, "trigger promise is not in a trigger function");
  			if (TRIGGER_FIRED_BEFORE(estate->trigdata->tg_event))
  				assign_text_var(estate, var, "BEFORE");
  			else if (TRIGGER_FIRED_AFTER(estate->trigdata->tg_event))
  				assign_text_var(estate, var, "AFTER");
  			else if (TRIGGER_FIRED_INSTEAD(estate->trigdata->tg_event))
  				assign_text_var(estate, var, "INSTEAD OF");
  			else
  				elog(ERROR, "unrecognized trigger execution time: not BEFORE, AFTER, or INSTEAD OF");
  			break;
  
  		case PLPGSQL_PROMISE_TG_LEVEL:
  			if (estate->trigdata == NULL)
  				elog(ERROR, "trigger promise is not in a trigger function");
  			if (TRIGGER_FIRED_FOR_ROW(estate->trigdata->tg_event))
  				assign_text_var(estate, var, "ROW");
  			else if (TRIGGER_FIRED_FOR_STATEMENT(estate->trigdata->tg_event))
  				assign_text_var(estate, var, "STATEMENT");
  			else
  				elog(ERROR, "unrecognized trigger event type: not ROW or STATEMENT");
  			break;
  
  		case PLPGSQL_PROMISE_TG_OP:
  			if (estate->trigdata == NULL)
  				elog(ERROR, "trigger promise is not in a trigger function");
  			if (TRIGGER_FIRED_BY_INSERT(estate->trigdata->tg_event))
  				assign_text_var(estate, var, "INSERT");
  			else if (TRIGGER_FIRED_BY_UPDATE(estate->trigdata->tg_event))
  				assign_text_var(estate, var, "UPDATE");
  			else if (TRIGGER_FIRED_BY_DELETE(estate->trigdata->tg_event))
  				assign_text_var(estate, var, "DELETE");
  			else if (TRIGGER_FIRED_BY_TRUNCATE(estate->trigdata->tg_event))
  				assign_text_var(estate, var, "TRUNCATE");
  			else
  				elog(ERROR, "unrecognized trigger action: not INSERT, DELETE, UPDATE, or TRUNCATE");
  			break;
  
  		case PLPGSQL_PROMISE_TG_RELID:
  			if (estate->trigdata == NULL)
  				elog(ERROR, "trigger promise is not in a trigger function");
  			assign_simple_var(estate, var,
  							  ObjectIdGetDatum(estate->trigdata->tg_relation->rd_id),
  							  false, false);
  			break;
  
  		case PLPGSQL_PROMISE_TG_TABLE_NAME:
  			if (estate->trigdata == NULL)
  				elog(ERROR, "trigger promise is not in a trigger function");
  			assign_simple_var(estate, var,
  							  DirectFunctionCall1(namein,
  												  CStringGetDatum(RelationGetRelationName(estate->trigdata->tg_relation))),
  							  false, true);
  			break;
  
  		case PLPGSQL_PROMISE_TG_TABLE_SCHEMA:
  			if (estate->trigdata == NULL)
  				elog(ERROR, "trigger promise is not in a trigger function");
  			assign_simple_var(estate, var,
  							  DirectFunctionCall1(namein,
  												  CStringGetDatum(get_namespace_name(RelationGetNamespace(estate->trigdata->tg_relation)))),
  							  false, true);
  			break;
  
  		case PLPGSQL_PROMISE_TG_NARGS:
  			if (estate->trigdata == NULL)
  				elog(ERROR, "trigger promise is not in a trigger function");
  			assign_simple_var(estate, var,
  							  Int16GetDatum(estate->trigdata->tg_trigger->tgnargs),
  							  false, false);
  			break;
  
  		case PLPGSQL_PROMISE_TG_ARGV:
  			if (estate->trigdata == NULL)
  				elog(ERROR, "trigger promise is not in a trigger function");
  			if (estate->trigdata->tg_trigger->tgnargs > 0)
  			{
  				/*
  				 * For historical reasons, tg_argv[] subscripts start at zero
  				 * not one.  So we can't use construct_array().
  				 */
  				int			nelems = estate->trigdata->tg_trigger->tgnargs;
  				Datum	   *elems;
  				int			dims[1];
  				int			lbs[1];
  				int			i;
  
  				elems = palloc(sizeof(Datum) * nelems);
  				for (i = 0; i < nelems; i++)
  					elems[i] = CStringGetTextDatum(estate->trigdata->tg_trigger->tgargs[i]);
  				dims[0] = nelems;
  				lbs[0] = 0;
  
  				assign_simple_var(estate, var,
  								  PointerGetDatum(construct_md_array(elems, NULL,
  																	 1, dims, lbs,
  																	 TEXTOID,
  																	 -1, false, 'i')),
  								  false, true);
  			}
  			else
  			{
  				assign_simple_var(estate, var, (Datum) 0, true, false);
  			}
  			break;
  
  		case PLPGSQL_PROMISE_TG_EVENT:
  			if (estate->evtrigdata == NULL)
  				elog(ERROR, "event trigger promise is not in an event trigger function");
  			assign_text_var(estate, var, estate->evtrigdata->event);
  			break;
  
  		case PLPGSQL_PROMISE_TG_TAG:
  			if (estate->evtrigdata == NULL)
  				elog(ERROR, "event trigger promise is not in an event trigger function");
  			assign_text_var(estate, var, estate->evtrigdata->tag);
  			break;
  
  		default:
  			elog(ERROR, "unrecognized promise type: %d", var->promise);
  	}
  
  	MemoryContextSwitchTo(oldcontext);
  }
  
  /*
   * Create a memory context for statement-lifespan variables, if we don't
   * have one already.  It will be a child of stmt_mcontext_parent, which is
   * either the function's main context or a pushed-down outer stmt_mcontext.
   */
  static MemoryContext
  get_stmt_mcontext(PLpgSQL_execstate *estate)
  {
  	if (estate->stmt_mcontext == NULL)
  	{
  		estate->stmt_mcontext =
  			AllocSetContextCreate(estate->stmt_mcontext_parent,
  								  "PLpgSQL per-statement data",
  								  ALLOCSET_DEFAULT_SIZES);
  	}
  	return estate->stmt_mcontext;
  }
  
  /*
   * Push down the current stmt_mcontext so that called statements won't use it.
   * This is needed by statements that have statement-lifespan data and need to
   * preserve it across some inner statements.  The caller should eventually do
   * pop_stmt_mcontext().
   */
  static void
  push_stmt_mcontext(PLpgSQL_execstate *estate)
  {
  	/* Should have done get_stmt_mcontext() first */
  	Assert(estate->stmt_mcontext != NULL);
  	/* Assert we've not messed up the stack linkage */
  	Assert(MemoryContextGetParent(estate->stmt_mcontext) == estate->stmt_mcontext_parent);
  	/* Push it down to become the parent of any nested stmt mcontext */
  	estate->stmt_mcontext_parent = estate->stmt_mcontext;
  	/* And make it not available for use directly */
  	estate->stmt_mcontext = NULL;
  }
  
  /*
   * Undo push_stmt_mcontext().  We assume this is done just before or after
   * resetting the caller's stmt_mcontext; since that action will also delete
   * any child contexts, there's no need to explicitly delete whatever context
   * might currently be estate->stmt_mcontext.
   */
  static void
  pop_stmt_mcontext(PLpgSQL_execstate *estate)
  {
  	/* We need only pop the stack */
  	estate->stmt_mcontext = estate->stmt_mcontext_parent;
  	estate->stmt_mcontext_parent = MemoryContextGetParent(estate->stmt_mcontext);
  }
  
  
  /*
   * Subroutine for exec_stmt_block: does any condition in the condition list
   * match the current exception?
   */
  static bool
  exception_matches_conditions(ErrorData *edata, PLpgSQL_condition *cond)
  {
  	for (; cond != NULL; cond = cond->next)
  	{
  		int			sqlerrstate = cond->sqlerrstate;
  
  		/*
  		 * OTHERS matches everything *except* query-canceled and
  		 * assert-failure.  If you're foolish enough, you can match those
  		 * explicitly.
  		 */
  		if (sqlerrstate == 0)
  		{
  			if (edata->sqlerrcode != ERRCODE_QUERY_CANCELED &&
  				edata->sqlerrcode != ERRCODE_ASSERT_FAILURE)
  				return true;
  		}
  		/* Exact match? */
  		else if (edata->sqlerrcode == sqlerrstate)
  			return true;
  		/* Category match? */
  		else if (ERRCODE_IS_CATEGORY(sqlerrstate) &&
  				 ERRCODE_TO_CATEGORY(edata->sqlerrcode) == sqlerrstate)
  			return true;
  	}
  	return false;
  }
  
  
  /* ----------
   * exec_stmt_block			Execute a block of statements
   * ----------
   */
  static int
  exec_stmt_block(PLpgSQL_execstate *estate, PLpgSQL_stmt_block *block)
  {
  	volatile int rc = -1;
  	int			i;
  
  	/*
  	 * First initialize all variables declared in this block
  	 */
  	estate->err_text = gettext_noop("during statement block local variable initialization");
  
  	for (i = 0; i < block->n_initvars; i++)
  	{
  		int			n = block->initvarnos[i];
  		PLpgSQL_datum *datum = estate->datums[n];
  
  		/*
  		 * The set of dtypes handled here must match plpgsql_add_initdatums().
  		 *
  		 * Note that we currently don't support promise datums within blocks,
  		 * only at a function's outermost scope, so we needn't handle those
  		 * here.
  		 */
  		switch (datum->dtype)
  		{
  			case PLPGSQL_DTYPE_VAR:
  				{
  					PLpgSQL_var *var = (PLpgSQL_var *) datum;
  
  					/*
  					 * Free any old value, in case re-entering block, and
  					 * initialize to NULL
  					 */
  					assign_simple_var(estate, var, (Datum) 0, true, false);
  
  					if (var->default_val == NULL)
  					{
  						/*
  						 * If needed, give the datatype a chance to reject
  						 * NULLs, by assigning a NULL to the variable.  We
  						 * claim the value is of type UNKNOWN, not the var's
  						 * datatype, else coercion will be skipped.
  						 */
  						if (var->datatype->typtype == TYPTYPE_DOMAIN)
  							exec_assign_value(estate,
  											  (PLpgSQL_datum *) var,
  											  (Datum) 0,
  											  true,
  											  UNKNOWNOID,
  											  -1);
  
  						/* parser should have rejected NOT NULL */
  						Assert(!var->notnull);
  					}
  					else
  					{
  						exec_assign_expr(estate, (PLpgSQL_datum *) var,
  										 var->default_val);
  					}
  				}
  				break;
  
  			case PLPGSQL_DTYPE_REC:
  				{
  					PLpgSQL_rec *rec = (PLpgSQL_rec *) datum;
  
  					/*
  					 * Deletion of any existing object will be handled during
  					 * the assignments below, and in some cases it's more
  					 * efficient for us not to get rid of it beforehand.
  					 */
  					if (rec->default_val == NULL)
  					{
  						/*
  						 * If needed, give the datatype a chance to reject
  						 * NULLs, by assigning a NULL to the variable.
  						 */
  						exec_move_row(estate, (PLpgSQL_variable *) rec,
  									  NULL, NULL);
  
  						/* parser should have rejected NOT NULL */
  						Assert(!rec->notnull);
  					}
  					else
  					{
  						exec_assign_expr(estate, (PLpgSQL_datum *) rec,
  										 rec->default_val);
  					}
  				}
  				break;
  
  			default:
  				elog(ERROR, "unrecognized dtype: %d", datum->dtype);
  		}
  	}
  
  	if (block->exceptions)
  	{
  		/*
  		 * Execute the statements in the block's body inside a sub-transaction
  		 */
  		MemoryContext oldcontext = CurrentMemoryContext;
  		ResourceOwner oldowner = CurrentResourceOwner;
  		ExprContext *old_eval_econtext = estate->eval_econtext;
  		ErrorData  *save_cur_error = estate->cur_error;
  		MemoryContext stmt_mcontext;
  
  		estate->err_text = gettext_noop("during statement block entry");
  
  		/*
  		 * We will need a stmt_mcontext to hold the error data if an error
  		 * occurs.  It seems best to force it to exist before entering the
  		 * subtransaction, so that we reduce the risk of out-of-memory during
  		 * error recovery, and because this greatly simplifies restoring the
  		 * stmt_mcontext stack to the correct state after an error.  We can
  		 * ameliorate the cost of this by allowing the called statements to
  		 * use this mcontext too; so we don't push it down here.
  		 */
  		stmt_mcontext = get_stmt_mcontext(estate);
  
  		BeginInternalSubTransaction(NULL);
  		/* Want to run statements inside function's memory context */
  		MemoryContextSwitchTo(oldcontext);
  
  		PG_TRY();
  		{
  			/*
  			 * We need to run the block's statements with a new eval_econtext
  			 * that belongs to the current subtransaction; if we try to use
  			 * the outer econtext then ExprContext shutdown callbacks will be
  			 * called at the wrong times.
  			 */
  			plpgsql_create_econtext(estate);
  
  			estate->err_text = NULL;
  
  			/* Run the block's statements */
  			rc = exec_stmts(estate, block->body);
  
  			estate->err_text = gettext_noop("during statement block exit");
  
  			/*
  			 * If the block ended with RETURN, we may need to copy the return
  			 * value out of the subtransaction eval_context.  We can avoid a
  			 * physical copy if the value happens to be a R/W expanded object.
  			 */
  			if (rc == PLPGSQL_RC_RETURN &&
  				!estate->retisset &&
  				!estate->retisnull)
  			{
  				int16		resTypLen;
  				bool		resTypByVal;
  
  				get_typlenbyval(estate->rettype, &resTypLen, &resTypByVal);
  				estate->retval = datumTransfer(estate->retval,
  											   resTypByVal, resTypLen);
  			}
  
  			/* Commit the inner transaction, return to outer xact context */
  			ReleaseCurrentSubTransaction();
  			MemoryContextSwitchTo(oldcontext);
  			CurrentResourceOwner = oldowner;
  
  			/* Assert that the stmt_mcontext stack is unchanged */
  			Assert(stmt_mcontext == estate->stmt_mcontext);
  
  			/*
  			 * Revert to outer eval_econtext.  (The inner one was
  			 * automatically cleaned up during subxact exit.)
  			 */
  			estate->eval_econtext = old_eval_econtext;
  		}
  		PG_CATCH();
  		{
  			ErrorData  *edata;
  			ListCell   *e;
  
  			estate->err_text = gettext_noop("during exception cleanup");
  
  			/* Save error info in our stmt_mcontext */
  			MemoryContextSwitchTo(stmt_mcontext);
  			edata = CopyErrorData();
  			FlushErrorState();
  
  			/* Abort the inner transaction */
  			RollbackAndReleaseCurrentSubTransaction();
  			MemoryContextSwitchTo(oldcontext);
  			CurrentResourceOwner = oldowner;
  
  			/*
  			 * Set up the stmt_mcontext stack as though we had restored our
  			 * previous state and then done push_stmt_mcontext().  The push is
  			 * needed so that statements in the exception handler won't
  			 * clobber the error data that's in our stmt_mcontext.
  			 */
  			estate->stmt_mcontext_parent = stmt_mcontext;
  			estate->stmt_mcontext = NULL;
  
  			/*
  			 * Now we can delete any nested stmt_mcontexts that might have
  			 * been created as children of ours.  (Note: we do not immediately
  			 * release any statement-lifespan data that might have been left
  			 * behind in stmt_mcontext itself.  We could attempt that by doing
  			 * a MemoryContextReset on it before collecting the error data
  			 * above, but it seems too risky to do any significant amount of
  			 * work before collecting the error.)
  			 */
  			MemoryContextDeleteChildren(stmt_mcontext);
  
  			/* Revert to outer eval_econtext */
  			estate->eval_econtext = old_eval_econtext;
  
  			/*
  			 * Must clean up the econtext too.  However, any tuple table made
  			 * in the subxact will have been thrown away by SPI during subxact
  			 * abort, so we don't need to (and mustn't try to) free the
  			 * eval_tuptable.
  			 */
  			estate->eval_tuptable = NULL;
  			exec_eval_cleanup(estate);
  
  			/* Look for a matching exception handler */
  			foreach(e, block->exceptions->exc_list)
  			{
  				PLpgSQL_exception *exception = (PLpgSQL_exception *) lfirst(e);
  
  				if (exception_matches_conditions(edata, exception->conditions))
  				{
  					/*
  					 * Initialize the magic SQLSTATE and SQLERRM variables for
  					 * the exception block; this also frees values from any
  					 * prior use of the same exception. We needn't do this
  					 * until we have found a matching exception.
  					 */
  					PLpgSQL_var *state_var;
  					PLpgSQL_var *errm_var;
  
  					state_var = (PLpgSQL_var *)
  						estate->datums[block->exceptions->sqlstate_varno];
  					errm_var = (PLpgSQL_var *)
  						estate->datums[block->exceptions->sqlerrm_varno];
  
  					assign_text_var(estate, state_var,
  									unpack_sql_state(edata->sqlerrcode));
  					assign_text_var(estate, errm_var, edata->message);
  
  					/*
  					 * Also set up cur_error so the error data is accessible
  					 * inside the handler.
  					 */
  					estate->cur_error = edata;
  
  					estate->err_text = NULL;
  
  					rc = exec_stmts(estate, exception->action);
  
  					break;
  				}
  			}
  
  			/*
  			 * Restore previous state of cur_error, whether or not we executed
  			 * a handler.  This is needed in case an error got thrown from
  			 * some inner block's exception handler.
  			 */
  			estate->cur_error = save_cur_error;
  
  			/* If no match found, re-throw the error */
  			if (e == NULL)
  				ReThrowError(edata);
  
  			/* Restore stmt_mcontext stack and release the error data */
  			pop_stmt_mcontext(estate);
  			MemoryContextReset(stmt_mcontext);
  		}
  		PG_END_TRY();
  
  		Assert(save_cur_error == estate->cur_error);
  	}
  	else
  	{
  		/*
  		 * Just execute the statements in the block's body
  		 */
  		estate->err_text = NULL;
  
  		rc = exec_stmts(estate, block->body);
  	}
  
  	estate->err_text = NULL;
  
  	/*
  	 * Handle the return code.  This is intentionally different from
  	 * LOOP_RC_PROCESSING(): CONTINUE never matches a block, and EXIT matches
  	 * a block only if there is a label match.
  	 */
  	switch (rc)
  	{
  		case PLPGSQL_RC_OK:
  		case PLPGSQL_RC_RETURN:
  		case PLPGSQL_RC_CONTINUE:
  			return rc;
  
  		case PLPGSQL_RC_EXIT:
  			if (estate->exitlabel == NULL)
  				return PLPGSQL_RC_EXIT;
  			if (block->label == NULL)
  				return PLPGSQL_RC_EXIT;
  			if (strcmp(block->label, estate->exitlabel) != 0)
  				return PLPGSQL_RC_EXIT;
  			estate->exitlabel = NULL;
  			return PLPGSQL_RC_OK;
  
  		default:
  			elog(ERROR, "unrecognized rc: %d", rc);
  	}
  
  	return PLPGSQL_RC_OK;
  }
  
  
  /* ----------
   * exec_stmts			Iterate over a list of statements
   *				as long as their return code is OK
   * ----------
   */
  static int
  exec_stmts(PLpgSQL_execstate *estate, List *stmts)
  {
  	ListCell   *s;
  
  	if (stmts == NIL)
  	{
  		/*
  		 * Ensure we do a CHECK_FOR_INTERRUPTS() even though there is no
  		 * statement.  This prevents hangup in a tight loop if, for instance,
  		 * there is a LOOP construct with an empty body.
  		 */
  		CHECK_FOR_INTERRUPTS();
  		return PLPGSQL_RC_OK;
  	}
  
  	foreach(s, stmts)
  	{
  		PLpgSQL_stmt *stmt = (PLpgSQL_stmt *) lfirst(s);
  		int			rc = exec_stmt(estate, stmt);
  
  		if (rc != PLPGSQL_RC_OK)
  			return rc;
  	}
  
  	return PLPGSQL_RC_OK;
  }
  
  
  /* ----------
   * exec_stmt			Distribute one statement to the statements
   *				type specific execution function.
   * ----------
   */
  static int
  exec_stmt(PLpgSQL_execstate *estate, PLpgSQL_stmt *stmt)
  {
  	PLpgSQL_stmt *save_estmt;
  	int			rc = -1;
  
  	save_estmt = estate->err_stmt;
  	estate->err_stmt = stmt;
  
  	/* Let the plugin know that we are about to execute this statement */
  	if (*plpgsql_plugin_ptr && (*plpgsql_plugin_ptr)->stmt_beg)
  		((*plpgsql_plugin_ptr)->stmt_beg) (estate, stmt);
  
  	CHECK_FOR_INTERRUPTS();
  
  	switch (stmt->cmd_type)
  	{
  		case PLPGSQL_STMT_BLOCK:
  			rc = exec_stmt_block(estate, (PLpgSQL_stmt_block *) stmt);
  			break;
  
  		case PLPGSQL_STMT_ASSIGN:
  			rc = exec_stmt_assign(estate, (PLpgSQL_stmt_assign *) stmt);
  			break;
  
  		case PLPGSQL_STMT_PERFORM:
  			rc = exec_stmt_perform(estate, (PLpgSQL_stmt_perform *) stmt);
  			break;
  
  		case PLPGSQL_STMT_CALL:
  			rc = exec_stmt_call(estate, (PLpgSQL_stmt_call *) stmt);
  			break;
  
  		case PLPGSQL_STMT_GETDIAG:
  			rc = exec_stmt_getdiag(estate, (PLpgSQL_stmt_getdiag *) stmt);
  			break;
  
  		case PLPGSQL_STMT_IF:
  			rc = exec_stmt_if(estate, (PLpgSQL_stmt_if *) stmt);
  			break;
  
  		case PLPGSQL_STMT_CASE:
  			rc = exec_stmt_case(estate, (PLpgSQL_stmt_case *) stmt);
  			break;
  
  		case PLPGSQL_STMT_LOOP:
  			rc = exec_stmt_loop(estate, (PLpgSQL_stmt_loop *) stmt);
  			break;
  
  		case PLPGSQL_STMT_WHILE:
  			rc = exec_stmt_while(estate, (PLpgSQL_stmt_while *) stmt);
  			break;
  
  		case PLPGSQL_STMT_FORI:
  			rc = exec_stmt_fori(estate, (PLpgSQL_stmt_fori *) stmt);
  			break;
  
  		case PLPGSQL_STMT_FORS:
  			rc = exec_stmt_fors(estate, (PLpgSQL_stmt_fors *) stmt);
  			break;
  
  		case PLPGSQL_STMT_FORC:
  			rc = exec_stmt_forc(estate, (PLpgSQL_stmt_forc *) stmt);
  			break;
  
  		case PLPGSQL_STMT_FOREACH_A:
  			rc = exec_stmt_foreach_a(estate, (PLpgSQL_stmt_foreach_a *) stmt);
  			break;
  
  		case PLPGSQL_STMT_EXIT:
  			rc = exec_stmt_exit(estate, (PLpgSQL_stmt_exit *) stmt);
  			break;
  
  		case PLPGSQL_STMT_RETURN:
  			rc = exec_stmt_return(estate, (PLpgSQL_stmt_return *) stmt);
  			break;
  
  		case PLPGSQL_STMT_RETURN_NEXT:
  			rc = exec_stmt_return_next(estate, (PLpgSQL_stmt_return_next *) stmt);
  			break;
  
  		case PLPGSQL_STMT_RETURN_QUERY:
  			rc = exec_stmt_return_query(estate, (PLpgSQL_stmt_return_query *) stmt);
  			break;
  
  		case PLPGSQL_STMT_RAISE:
  			rc = exec_stmt_raise(estate, (PLpgSQL_stmt_raise *) stmt);
  			break;
  
  		case PLPGSQL_STMT_ASSERT:
  			rc = exec_stmt_assert(estate, (PLpgSQL_stmt_assert *) stmt);
  			break;
  
  		case PLPGSQL_STMT_EXECSQL:
  			rc = exec_stmt_execsql(estate, (PLpgSQL_stmt_execsql *) stmt);
  			break;
  
  		case PLPGSQL_STMT_DYNEXECUTE:
  			rc = exec_stmt_dynexecute(estate, (PLpgSQL_stmt_dynexecute *) stmt);
  			break;
  
  		case PLPGSQL_STMT_DYNFORS:
  			rc = exec_stmt_dynfors(estate, (PLpgSQL_stmt_dynfors *) stmt);
  			break;
  
  		case PLPGSQL_STMT_OPEN:
  			rc = exec_stmt_open(estate, (PLpgSQL_stmt_open *) stmt);
  			break;
  
  		case PLPGSQL_STMT_FETCH:
  			rc = exec_stmt_fetch(estate, (PLpgSQL_stmt_fetch *) stmt);
  			break;
  
  		case PLPGSQL_STMT_CLOSE:
  			rc = exec_stmt_close(estate, (PLpgSQL_stmt_close *) stmt);
  			break;
  
  		case PLPGSQL_STMT_COMMIT:
  			rc = exec_stmt_commit(estate, (PLpgSQL_stmt_commit *) stmt);
  			break;
  
  		case PLPGSQL_STMT_ROLLBACK:
  			rc = exec_stmt_rollback(estate, (PLpgSQL_stmt_rollback *) stmt);
  			break;
  
  		case PLPGSQL_STMT_SET:
  			rc = exec_stmt_set(estate, (PLpgSQL_stmt_set *) stmt);
  			break;
  
  		default:
  			estate->err_stmt = save_estmt;
  			elog(ERROR, "unrecognized cmd_type: %d", stmt->cmd_type);
  	}
  
  	/* Let the plugin know that we have finished executing this statement */
  	if (*plpgsql_plugin_ptr && (*plpgsql_plugin_ptr)->stmt_end)
  		((*plpgsql_plugin_ptr)->stmt_end) (estate, stmt);
  
  	estate->err_stmt = save_estmt;
  
  	return rc;
  }
  
  
  /* ----------
   * exec_stmt_assign			Evaluate an expression and
   *					put the result into a variable.
   * ----------
   */
  static int
  exec_stmt_assign(PLpgSQL_execstate *estate, PLpgSQL_stmt_assign *stmt)
  {
  	Assert(stmt->varno >= 0);
  
  	exec_assign_expr(estate, estate->datums[stmt->varno], stmt->expr);
  
  	return PLPGSQL_RC_OK;
  }
  
  /* ----------
   * exec_stmt_perform		Evaluate query and discard result (but set
   *							FOUND depending on whether at least one row
   *							was returned).
   * ----------
   */
  static int
  exec_stmt_perform(PLpgSQL_execstate *estate, PLpgSQL_stmt_perform *stmt)
  {
  	PLpgSQL_expr *expr = stmt->expr;
  
  	(void) exec_run_select(estate, expr, 0, NULL);
  	exec_set_found(estate, (estate->eval_processed != 0));
  	exec_eval_cleanup(estate);
  
  	return PLPGSQL_RC_OK;
  }
  
  /*
   * exec_stmt_call
   */
  static int
  exec_stmt_call(PLpgSQL_execstate *estate, PLpgSQL_stmt_call *stmt)
  {
  	PLpgSQL_expr *expr = stmt->expr;
  	volatile LocalTransactionId before_lxid;
  	LocalTransactionId after_lxid;
  	volatile bool pushed_active_snap = false;
  	volatile int rc;
  
  	/* PG_TRY to ensure we clear the plan link, if needed, on failure */
  	PG_TRY();
  	{
  		SPIPlanPtr	plan = expr->plan;
  		ParamListInfo paramLI;
  
  		if (plan == NULL)
  		{
  
  			/*
  			 * Don't save the plan if not in atomic context.  Otherwise,
  			 * transaction ends would cause errors about plancache leaks.
  			 *
  			 * XXX This would be fixable with some plancache/resowner surgery
  			 * elsewhere, but for now we'll just work around this here.
  			 */
  			exec_prepare_plan(estate, expr, 0, estate->atomic);
  
  			/*
  			 * The procedure call could end transactions, which would upset
  			 * the snapshot management in SPI_execute*, so don't let it do it.
  			 * Instead, we set the snapshots ourselves below.
  			 */
  			plan = expr->plan;
  			plan->no_snapshots = true;
  
  			/*
  			 * Force target to be recalculated whenever the plan changes, in
  			 * case the procedure's argument list has changed.
  			 */
  			stmt->target = NULL;
  		}
  
  		/*
  		 * We construct a DTYPE_ROW datum representing the plpgsql variables
  		 * associated with the procedure's output arguments.  Then we can use
  		 * exec_move_row() to do the assignments.
  		 */
  		if (stmt->is_call && stmt->target == NULL)
  		{
  			Node	   *node;
  			FuncExpr   *funcexpr;
  			HeapTuple	func_tuple;
  			List	   *funcargs;
  			Oid		   *argtypes;
  			char	  **argnames;
  			char	   *argmodes;
  			MemoryContext oldcontext;
  			PLpgSQL_row *row;
  			int			nfields;
  			int			i;
  			ListCell   *lc;
  
  			/*
  			 * Get the parsed CallStmt, and look up the called procedure
  			 */
  			node = linitial_node(Query,
  								 ((CachedPlanSource *) linitial(plan->plancache_list))->query_list)->utilityStmt;
  			if (node == NULL || !IsA(node, CallStmt))
  				elog(ERROR, "query for CALL statement is not a CallStmt");
  
  			funcexpr = ((CallStmt *) node)->funcexpr;
  
  			func_tuple = SearchSysCache1(PROCOID,
  										 ObjectIdGetDatum(funcexpr->funcid));
  			if (!HeapTupleIsValid(func_tuple))
  				elog(ERROR, "cache lookup failed for function %u",
  					 funcexpr->funcid);
  
  			/*
  			 * Extract function arguments, and expand any named-arg notation
  			 */
  			funcargs = expand_function_arguments(funcexpr->args,
  												 funcexpr->funcresulttype,
  												 func_tuple);
  
  			/*
  			 * Get the argument names and modes, too
  			 */
  			get_func_arg_info(func_tuple, &argtypes, &argnames, &argmodes);
  
  			ReleaseSysCache(func_tuple);
  
  			/*
  			 * Begin constructing row Datum
  			 */
  			oldcontext = MemoryContextSwitchTo(estate->func->fn_cxt);
  
  			row = (PLpgSQL_row *) palloc0(sizeof(PLpgSQL_row));
  			row->dtype = PLPGSQL_DTYPE_ROW;
  			row->refname = "(unnamed row)";
  			row->lineno = -1;
  			row->varnos = (int *) palloc(sizeof(int) * list_length(funcargs));
  
  			MemoryContextSwitchTo(oldcontext);
  
  			/*
  			 * Examine procedure's argument list.  Each output arg position
  			 * should be an unadorned plpgsql variable (Datum), which we can
  			 * insert into the row Datum.
  			 */
  			nfields = 0;
  			i = 0;
  			foreach(lc, funcargs)
  			{
  				Node	   *n = lfirst(lc);
  
  				if (argmodes &&
  					(argmodes[i] == PROARGMODE_INOUT ||
  					 argmodes[i] == PROARGMODE_OUT))
  				{
  					if (IsA(n, Param))
  					{
  						Param	   *param = (Param *) n;
  
  						/* paramid is offset by 1 (see make_datum_param()) */
  						row->varnos[nfields++] = param->paramid - 1;
  					}
  					else
  					{
  						/* report error using parameter name, if available */
  						if (argnames && argnames[i] && argnames[i][0])
  							ereport(ERROR,
  									(errcode(ERRCODE_SYNTAX_ERROR),
  									 errmsg("procedure parameter \"%s\" is an output parameter but corresponding argument is not writable",
  											argnames[i])));
  						else
  							ereport(ERROR,
  									(errcode(ERRCODE_SYNTAX_ERROR),
  									 errmsg("procedure parameter %d is an output parameter but corresponding argument is not writable",
  											i + 1)));
  					}
  				}
  				i++;
  			}
  
  			row->nfields = nfields;
  
  			stmt->target = (PLpgSQL_variable *) row;
  		}
  
  		paramLI = setup_param_list(estate, expr);
  
  		before_lxid = MyProc->lxid;
  
  		/*
  		 * Set snapshot only for non-read-only procedures, similar to SPI
  		 * behavior.
  		 */
  		if (!estate->readonly_func)
  		{
  			PushActiveSnapshot(GetTransactionSnapshot());
  			pushed_active_snap = true;
  		}
  
  		rc = SPI_execute_plan_with_paramlist(expr->plan, paramLI,
  											 estate->readonly_func, 0);
  	}
  	PG_CATCH();
  	{
  		/*
  		 * If we aren't saving the plan, unset the pointer.  Note that it
  		 * could have been unset already, in case of a recursive call.
  		 */
  		if (expr->plan && !expr->plan->saved)
  			expr->plan = NULL;
  		PG_RE_THROW();
  	}
  	PG_END_TRY();
  
  	if (expr->plan && !expr->plan->saved)
  		expr->plan = NULL;
  
  	if (rc < 0)
  		elog(ERROR, "SPI_execute_plan_with_paramlist failed executing query \"%s\": %s",
  			 expr->query, SPI_result_code_string(rc));
  
  	after_lxid = MyProc->lxid;
  
  	if (before_lxid == after_lxid)
  	{
  		/*
  		 * If we are still in the same transaction after the call, pop the
  		 * snapshot that we might have pushed.  (If it's a new transaction,
  		 * then all the snapshots are gone already.)
  		 */
  		if (pushed_active_snap)
  			PopActiveSnapshot();
  	}
  	else
  	{
  		/*
  		 * If we are in a new transaction after the call, we need to reset
  		 * some internal state.
  		 */
  		estate->simple_eval_estate = NULL;
  		plpgsql_create_econtext(estate);
  	}
  
  	/*
  	 * Check result rowcount; if there's one row, assign procedure's output
  	 * values back to the appropriate variables.
  	 */
  	if (SPI_processed == 1)
  	{
  		SPITupleTable *tuptab = SPI_tuptable;
  
  		if (!stmt->target)
  			elog(ERROR, "DO statement returned a row");
  
  		exec_move_row(estate, stmt->target, tuptab->vals[0], tuptab->tupdesc);
  	}
  	else if (SPI_processed > 1)
  		elog(ERROR, "procedure call returned more than one row");
  
  	exec_eval_cleanup(estate);
  	SPI_freetuptable(SPI_tuptable);
  
  	return PLPGSQL_RC_OK;
  }
  
  /* ----------
   * exec_stmt_getdiag					Put internal PG information into
   *										specified variables.
   * ----------
   */
  static int
  exec_stmt_getdiag(PLpgSQL_execstate *estate, PLpgSQL_stmt_getdiag *stmt)
  {
  	ListCell   *lc;
  
  	/*
  	 * GET STACKED DIAGNOSTICS is only valid inside an exception handler.
  	 *
  	 * Note: we trust the grammar to have disallowed the relevant item kinds
  	 * if not is_stacked, otherwise we'd dump core below.
  	 */
  	if (stmt->is_stacked && estate->cur_error == NULL)
  		ereport(ERROR,
  				(errcode(ERRCODE_STACKED_DIAGNOSTICS_ACCESSED_WITHOUT_ACTIVE_HANDLER),
  				 errmsg("GET STACKED DIAGNOSTICS cannot be used outside an exception handler")));
  
  	foreach(lc, stmt->diag_items)
  	{
  		PLpgSQL_diag_item *diag_item = (PLpgSQL_diag_item *) lfirst(lc);
  		PLpgSQL_datum *var = estate->datums[diag_item->target];
  
  		switch (diag_item->kind)
  		{
  			case PLPGSQL_GETDIAG_ROW_COUNT:
  				exec_assign_value(estate, var,
  								  UInt64GetDatum(estate->eval_processed),
  								  false, INT8OID, -1);
  				break;
  
  			case PLPGSQL_GETDIAG_ERROR_CONTEXT:
  				exec_assign_c_string(estate, var,
  									 estate->cur_error->context);
  				break;
  
  			case PLPGSQL_GETDIAG_ERROR_DETAIL:
  				exec_assign_c_string(estate, var,
  									 estate->cur_error->detail);
  				break;
  
  			case PLPGSQL_GETDIAG_ERROR_HINT:
  				exec_assign_c_string(estate, var,
  									 estate->cur_error->hint);
  				break;
  
  			case PLPGSQL_GETDIAG_RETURNED_SQLSTATE:
  				exec_assign_c_string(estate, var,
  									 unpack_sql_state(estate->cur_error->sqlerrcode));
  				break;
  
  			case PLPGSQL_GETDIAG_COLUMN_NAME:
  				exec_assign_c_string(estate, var,
  									 estate->cur_error->column_name);
  				break;
  
  			case PLPGSQL_GETDIAG_CONSTRAINT_NAME:
  				exec_assign_c_string(estate, var,
  									 estate->cur_error->constraint_name);
  				break;
  
  			case PLPGSQL_GETDIAG_DATATYPE_NAME:
  				exec_assign_c_string(estate, var,
  									 estate->cur_error->datatype_name);
  				break;
  
  			case PLPGSQL_GETDIAG_MESSAGE_TEXT:
  				exec_assign_c_string(estate, var,
  									 estate->cur_error->message);
  				break;
  
  			case PLPGSQL_GETDIAG_TABLE_NAME:
  				exec_assign_c_string(estate, var,
  									 estate->cur_error->table_name);
  				break;
  
  			case PLPGSQL_GETDIAG_SCHEMA_NAME:
  				exec_assign_c_string(estate, var,
  									 estate->cur_error->schema_name);
  				break;
  
  			case PLPGSQL_GETDIAG_CONTEXT:
  				{
  					char	   *contextstackstr;
  					MemoryContext oldcontext;
  
  					/* Use eval_mcontext for short-lived string */
  					oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate));
  					contextstackstr = GetErrorContextStack();
  					MemoryContextSwitchTo(oldcontext);
  
  					exec_assign_c_string(estate, var, contextstackstr);
  				}
  				break;
  
  			default:
  				elog(ERROR, "unrecognized diagnostic item kind: %d",
  					 diag_item->kind);
  		}
  	}
  
  	exec_eval_cleanup(estate);
  
  	return PLPGSQL_RC_OK;
  }
  
  /* ----------
   * exec_stmt_if				Evaluate a bool expression and
   *					execute the true or false body
   *					conditionally.
   * ----------
   */
  static int
  exec_stmt_if(PLpgSQL_execstate *estate, PLpgSQL_stmt_if *stmt)
  {
  	bool		value;
  	bool		isnull;
  	ListCell   *lc;
  
  	value = exec_eval_boolean(estate, stmt->cond, &isnull);
  	exec_eval_cleanup(estate);
  	if (!isnull && value)
  		return exec_stmts(estate, stmt->then_body);
  
  	foreach(lc, stmt->elsif_list)
  	{
  		PLpgSQL_if_elsif *elif = (PLpgSQL_if_elsif *) lfirst(lc);
  
  		value = exec_eval_boolean(estate, elif->cond, &isnull);
  		exec_eval_cleanup(estate);
  		if (!isnull && value)
  			return exec_stmts(estate, elif->stmts);
  	}
  
  	return exec_stmts(estate, stmt->else_body);
  }
  
  
  /*-----------
   * exec_stmt_case
   *-----------
   */
  static int
  exec_stmt_case(PLpgSQL_execstate *estate, PLpgSQL_stmt_case *stmt)
  {
  	PLpgSQL_var *t_var = NULL;
  	bool		isnull;
  	ListCell   *l;
  
  	if (stmt->t_expr != NULL)
  	{
  		/* simple case */
  		Datum		t_val;
  		Oid			t_typoid;
  		int32		t_typmod;
  
  		t_val = exec_eval_expr(estate, stmt->t_expr,
  							   &isnull, &t_typoid, &t_typmod);
  
  		t_var = (PLpgSQL_var *) estate->datums[stmt->t_varno];
  
  		/*
  		 * When expected datatype is different from real, change it. Note that
  		 * what we're modifying here is an execution copy of the datum, so
  		 * this doesn't affect the originally stored function parse tree. (In
  		 * theory, if the expression datatype keeps changing during execution,
  		 * this could cause a function-lifespan memory leak.  Doesn't seem
  		 * worth worrying about though.)
  		 */
  		if (t_var->datatype->typoid != t_typoid ||
  			t_var->datatype->atttypmod != t_typmod)
  			t_var->datatype = plpgsql_build_datatype(t_typoid,
  													 t_typmod,
  													 estate->func->fn_input_collation,
  													 NULL);
  
  		/* now we can assign to the variable */
  		exec_assign_value(estate,
  						  (PLpgSQL_datum *) t_var,
  						  t_val,
  						  isnull,
  						  t_typoid,
  						  t_typmod);
  
  		exec_eval_cleanup(estate);
  	}
  
  	/* Now search for a successful WHEN clause */
  	foreach(l, stmt->case_when_list)
  	{
  		PLpgSQL_case_when *cwt = (PLpgSQL_case_when *) lfirst(l);
  		bool		value;
  
  		value = exec_eval_boolean(estate, cwt->expr, &isnull);
  		exec_eval_cleanup(estate);
  		if (!isnull && value)
  		{
  			/* Found it */
  
  			/* We can now discard any value we had for the temp variable */
  			if (t_var != NULL)
  				assign_simple_var(estate, t_var, (Datum) 0, true, false);
  
  			/* Evaluate the statement(s), and we're done */
  			return exec_stmts(estate, cwt->stmts);
  		}
  	}
  
  	/* We can now discard any value we had for the temp variable */
  	if (t_var != NULL)
  		assign_simple_var(estate, t_var, (Datum) 0, true, false);
  
  	/* SQL2003 mandates this error if there was no ELSE clause */
  	if (!stmt->have_else)
  		ereport(ERROR,
  				(errcode(ERRCODE_CASE_NOT_FOUND),
  				 errmsg("case not found"),
  				 errhint("CASE statement is missing ELSE part.")));
  
  	/* Evaluate the ELSE statements, and we're done */
  	return exec_stmts(estate, stmt->else_stmts);
  }
  
  
  /* ----------
   * exec_stmt_loop			Loop over statements until
   *					an exit occurs.
   * ----------
   */
  static int
  exec_stmt_loop(PLpgSQL_execstate *estate, PLpgSQL_stmt_loop *stmt)
  {
  	int			rc = PLPGSQL_RC_OK;
  
  	for (;;)
  	{
  		rc = exec_stmts(estate, stmt->body);
  
  		LOOP_RC_PROCESSING(stmt->label, break);
  	}
  
  	return rc;
  }
  
  
  /* ----------
   * exec_stmt_while			Loop over statements as long
   *					as an expression evaluates to
   *					true or an exit occurs.
   * ----------
   */
  static int
  exec_stmt_while(PLpgSQL_execstate *estate, PLpgSQL_stmt_while *stmt)
  {
  	int			rc = PLPGSQL_RC_OK;
  
  	for (;;)
  	{
  		bool		value;
  		bool		isnull;
  
  		value = exec_eval_boolean(estate, stmt->cond, &isnull);
  		exec_eval_cleanup(estate);
  
  		if (isnull || !value)
  			break;
  
  		rc = exec_stmts(estate, stmt->body);
  
  		LOOP_RC_PROCESSING(stmt->label, break);
  	}
  
  	return rc;
  }
  
  
  /* ----------
   * exec_stmt_fori			Iterate an integer variable
   *					from a lower to an upper value
   *					incrementing or decrementing by the BY value
   * ----------
   */
  static int
  exec_stmt_fori(PLpgSQL_execstate *estate, PLpgSQL_stmt_fori *stmt)
  {
  	PLpgSQL_var *var;
  	Datum		value;
  	bool		isnull;
  	Oid			valtype;
  	int32		valtypmod;
  	int32		loop_value;
  	int32		end_value;
  	int32		step_value;
  	bool		found = false;
  	int			rc = PLPGSQL_RC_OK;
  
  	var = (PLpgSQL_var *) (estate->datums[stmt->var->dno]);
  
  	/*
  	 * Get the value of the lower bound
  	 */
  	value = exec_eval_expr(estate, stmt->lower,
  						   &isnull, &valtype, &valtypmod);
  	value = exec_cast_value(estate, value, &isnull,
  							valtype, valtypmod,
  							var->datatype->typoid,
  							var->datatype->atttypmod);
  	if (isnull)
  		ereport(ERROR,
  				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
  				 errmsg("lower bound of FOR loop cannot be null")));
  	loop_value = DatumGetInt32(value);
  	exec_eval_cleanup(estate);
  
  	/*
  	 * Get the value of the upper bound
  	 */
  	value = exec_eval_expr(estate, stmt->upper,
  						   &isnull, &valtype, &valtypmod);
  	value = exec_cast_value(estate, value, &isnull,
  							valtype, valtypmod,
  							var->datatype->typoid,
  							var->datatype->atttypmod);
  	if (isnull)
  		ereport(ERROR,
  				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
  				 errmsg("upper bound of FOR loop cannot be null")));
  	end_value = DatumGetInt32(value);
  	exec_eval_cleanup(estate);
  
  	/*
  	 * Get the step value
  	 */
  	if (stmt->step)
  	{
  		value = exec_eval_expr(estate, stmt->step,
  							   &isnull, &valtype, &valtypmod);
  		value = exec_cast_value(estate, value, &isnull,
  								valtype, valtypmod,
  								var->datatype->typoid,
  								var->datatype->atttypmod);
  		if (isnull)
  			ereport(ERROR,
  					(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
  					 errmsg("BY value of FOR loop cannot be null")));
  		step_value = DatumGetInt32(value);
  		exec_eval_cleanup(estate);
  		if (step_value <= 0)
  			ereport(ERROR,
  					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  					 errmsg("BY value of FOR loop must be greater than zero")));
  	}
  	else
  		step_value = 1;
  
  	/*
  	 * Now do the loop
  	 */
  	for (;;)
  	{
  		/*
  		 * Check against upper bound
  		 */
  		if (stmt->reverse)
  		{
  			if (loop_value < end_value)
  				break;
  		}
  		else
  		{
  			if (loop_value > end_value)
  				break;
  		}
  
  		found = true;			/* looped at least once */
  
  		/*
  		 * Assign current value to loop var
  		 */
  		assign_simple_var(estate, var, Int32GetDatum(loop_value), false, false);
  
  		/*
  		 * Execute the statements
  		 */
  		rc = exec_stmts(estate, stmt->body);
  
  		LOOP_RC_PROCESSING(stmt->label, break);
  
  		/*
  		 * Increase/decrease loop value, unless it would overflow, in which
  		 * case exit the loop.
  		 */
  		if (stmt->reverse)
  		{
  			if (loop_value < (PG_INT32_MIN + step_value))
  				break;
  			loop_value -= step_value;
  		}
  		else
  		{
  			if (loop_value > (PG_INT32_MAX - step_value))
  				break;
  			loop_value += step_value;
  		}
  	}
  
  	/*
  	 * Set the FOUND variable to indicate the result of executing the loop
  	 * (namely, whether we looped one or more times). This must be set here so
  	 * that it does not interfere with the value of the FOUND variable inside
  	 * the loop processing itself.
  	 */
  	exec_set_found(estate, found);
  
  	return rc;
  }
  
  
  /* ----------
   * exec_stmt_fors			Execute a query, assign each
   *					tuple to a record or row and
   *					execute a group of statements
   *					for it.
   * ----------
   */
  static int
  exec_stmt_fors(PLpgSQL_execstate *estate, PLpgSQL_stmt_fors *stmt)
  {
  	Portal		portal;
  	int			rc;
  
  	/*
  	 * Open the implicit cursor for the statement using exec_run_select
  	 */
  	exec_run_select(estate, stmt->query, 0, &portal);
  
  	/*
  	 * Execute the loop
  	 */
  	rc = exec_for_query(estate, (PLpgSQL_stmt_forq *) stmt, portal, true);
  
  	/*
  	 * Close the implicit cursor
  	 */
  	SPI_cursor_close(portal);
  
  	return rc;
  }
  
  
  /* ----------
   * exec_stmt_forc			Execute a loop for each row from a cursor.
   * ----------
   */
  static int
  exec_stmt_forc(PLpgSQL_execstate *estate, PLpgSQL_stmt_forc *stmt)
  {
  	PLpgSQL_var *curvar;
  	MemoryContext stmt_mcontext = NULL;
  	char	   *curname = NULL;
  	PLpgSQL_expr *query;
  	ParamListInfo paramLI;
  	Portal		portal;
  	int			rc;
  
  	/* ----------
  	 * Get the cursor variable and if it has an assigned name, check
  	 * that it's not in use currently.
  	 * ----------
  	 */
  	curvar = (PLpgSQL_var *) (estate->datums[stmt->curvar]);
  	if (!curvar->isnull)
  	{
  		MemoryContext oldcontext;
  
  		/* We only need stmt_mcontext to hold the cursor name string */
  		stmt_mcontext = get_stmt_mcontext(estate);
  		oldcontext = MemoryContextSwitchTo(stmt_mcontext);
  		curname = TextDatumGetCString(curvar->value);
  		MemoryContextSwitchTo(oldcontext);
  
  		if (SPI_cursor_find(curname) != NULL)
  			ereport(ERROR,
  					(errcode(ERRCODE_DUPLICATE_CURSOR),
  					 errmsg("cursor \"%s\" already in use", curname)));
  	}
  
  	/* ----------
  	 * Open the cursor just like an OPEN command
  	 *
  	 * Note: parser should already have checked that statement supplies
  	 * args iff cursor needs them, but we check again to be safe.
  	 * ----------
  	 */
  	if (stmt->argquery != NULL)
  	{
  		/* ----------
  		 * OPEN CURSOR with args.  We fake a SELECT ... INTO ...
  		 * statement to evaluate the args and put 'em into the
  		 * internal row.
  		 * ----------
  		 */
  		PLpgSQL_stmt_execsql set_args;
  
  		if (curvar->cursor_explicit_argrow < 0)
  			ereport(ERROR,
  					(errcode(ERRCODE_SYNTAX_ERROR),
  					 errmsg("arguments given for cursor without arguments")));
  
  		memset(&set_args, 0, sizeof(set_args));
  		set_args.cmd_type = PLPGSQL_STMT_EXECSQL;
  		set_args.lineno = stmt->lineno;
  		set_args.sqlstmt = stmt->argquery;
  		set_args.into = true;
  		/* XXX historically this has not been STRICT */
  		set_args.target = (PLpgSQL_variable *)
  			(estate->datums[curvar->cursor_explicit_argrow]);
  
  		if (exec_stmt_execsql(estate, &set_args) != PLPGSQL_RC_OK)
  			elog(ERROR, "open cursor failed during argument processing");
  	}
  	else
  	{
  		if (curvar->cursor_explicit_argrow >= 0)
  			ereport(ERROR,
  					(errcode(ERRCODE_SYNTAX_ERROR),
  					 errmsg("arguments required for cursor")));
  	}
  
  	query = curvar->cursor_explicit_expr;
  	Assert(query);
  
  	if (query->plan == NULL)
  		exec_prepare_plan(estate, query, curvar->cursor_options, true);
  
  	/*
  	 * Set up ParamListInfo for this query
  	 */
  	paramLI = setup_param_list(estate, query);
  
  	/*
  	 * Open the cursor (the paramlist will get copied into the portal)
  	 */
  	portal = SPI_cursor_open_with_paramlist(curname, query->plan,
  											paramLI,
  											estate->readonly_func);
  	if (portal == NULL)
  		elog(ERROR, "could not open cursor: %s",
  			 SPI_result_code_string(SPI_result));
  
  	/*
  	 * If cursor variable was NULL, store the generated portal name in it
  	 */
  	if (curname == NULL)
  		assign_text_var(estate, curvar, portal->name);
  
  	/*
  	 * Clean up before entering exec_for_query
  	 */
  	exec_eval_cleanup(estate);
  	if (stmt_mcontext)
  		MemoryContextReset(stmt_mcontext);
  
  	/*
  	 * Execute the loop.  We can't prefetch because the cursor is accessible
  	 * to the user, for instance via UPDATE WHERE CURRENT OF within the loop.
  	 */
  	rc = exec_for_query(estate, (PLpgSQL_stmt_forq *) stmt, portal, false);
  
  	/* ----------
  	 * Close portal, and restore cursor variable if it was initially NULL.
  	 * ----------
  	 */
  	SPI_cursor_close(portal);
  
  	if (curname == NULL)
  		assign_simple_var(estate, curvar, (Datum) 0, true, false);
  
  	return rc;
  }
  
  
  /* ----------
   * exec_stmt_foreach_a			Loop over elements or slices of an array
   *
   * When looping over elements, the loop variable is the same type that the
   * array stores (eg: integer), when looping through slices, the loop variable
   * is an array of size and dimensions to match the size of the slice.
   * ----------
   */
  static int
  exec_stmt_foreach_a(PLpgSQL_execstate *estate, PLpgSQL_stmt_foreach_a *stmt)
  {
  	ArrayType  *arr;
  	Oid			arrtype;
  	int32		arrtypmod;
  	PLpgSQL_datum *loop_var;
  	Oid			loop_var_elem_type;
  	bool		found = false;
  	int			rc = PLPGSQL_RC_OK;
  	MemoryContext stmt_mcontext;
  	MemoryContext oldcontext;
  	ArrayIterator array_iterator;
  	Oid			iterator_result_type;
  	int32		iterator_result_typmod;
  	Datum		value;
  	bool		isnull;
  
  	/* get the value of the array expression */
  	value = exec_eval_expr(estate, stmt->expr, &isnull, &arrtype, &arrtypmod);
  	if (isnull)
  		ereport(ERROR,
  				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
  				 errmsg("FOREACH expression must not be null")));
  
  	/*
  	 * Do as much as possible of the code below in stmt_mcontext, to avoid any
  	 * leaks from called subroutines.  We need a private stmt_mcontext since
  	 * we'll be calling arbitrary statement code.
  	 */
  	stmt_mcontext = get_stmt_mcontext(estate);
  	push_stmt_mcontext(estate);
  	oldcontext = MemoryContextSwitchTo(stmt_mcontext);
  
  	/* check the type of the expression - must be an array */
  	if (!OidIsValid(get_element_type(arrtype)))
  		ereport(ERROR,
  				(errcode(ERRCODE_DATATYPE_MISMATCH),
  				 errmsg("FOREACH expression must yield an array, not type %s",
  						format_type_be(arrtype))));
  
  	/*
  	 * We must copy the array into stmt_mcontext, else it will disappear in
  	 * exec_eval_cleanup.  This is annoying, but cleanup will certainly happen
  	 * while running the loop body, so we have little choice.
  	 */
  	arr = DatumGetArrayTypePCopy(value);
  
  	/* Clean up any leftover temporary memory */
  	exec_eval_cleanup(estate);
  
  	/* Slice dimension must be less than or equal to array dimension */
  	if (stmt->slice < 0 || stmt->slice > ARR_NDIM(arr))
  		ereport(ERROR,
  				(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
  				 errmsg("slice dimension (%d) is out of the valid range 0..%d",
  						stmt->slice, ARR_NDIM(arr))));
  
  	/* Set up the loop variable and see if it is of an array type */
  	loop_var = estate->datums[stmt->varno];
  	if (loop_var->dtype == PLPGSQL_DTYPE_REC ||
  		loop_var->dtype == PLPGSQL_DTYPE_ROW)
  	{
  		/*
  		 * Record/row variable is certainly not of array type, and might not
  		 * be initialized at all yet, so don't try to get its type
  		 */
  		loop_var_elem_type = InvalidOid;
  	}
  	else
  		loop_var_elem_type = get_element_type(plpgsql_exec_get_datum_type(estate,
  																		  loop_var));
  
  	/*
  	 * Sanity-check the loop variable type.  We don't try very hard here, and
  	 * should not be too picky since it's possible that exec_assign_value can
  	 * coerce values of different types.  But it seems worthwhile to complain
  	 * if the array-ness of the loop variable is not right.
  	 */
  	if (stmt->slice > 0 && loop_var_elem_type == InvalidOid)
  		ereport(ERROR,
  				(errcode(ERRCODE_DATATYPE_MISMATCH),
  				 errmsg("FOREACH ... SLICE loop variable must be of an array type")));
  	if (stmt->slice == 0 && loop_var_elem_type != InvalidOid)
  		ereport(ERROR,
  				(errcode(ERRCODE_DATATYPE_MISMATCH),
  				 errmsg("FOREACH loop variable must not be of an array type")));
  
  	/* Create an iterator to step through the array */
  	array_iterator = array_create_iterator(arr, stmt->slice, NULL);
  
  	/* Identify iterator result type */
  	if (stmt->slice > 0)
  	{
  		/* When slicing, nominal type of result is same as array type */
  		iterator_result_type = arrtype;
  		iterator_result_typmod = arrtypmod;
  	}
  	else
  	{
  		/* Without slicing, results are individual array elements */
  		iterator_result_type = ARR_ELEMTYPE(arr);
  		iterator_result_typmod = arrtypmod;
  	}
  
  	/* Iterate over the array elements or slices */
  	while (array_iterate(array_iterator, &value, &isnull))
  	{
  		found = true;			/* looped at least once */
  
  		/* exec_assign_value and exec_stmts must run in the main context */
  		MemoryContextSwitchTo(oldcontext);
  
  		/* Assign current element/slice to the loop variable */
  		exec_assign_value(estate, loop_var, value, isnull,
  						  iterator_result_type, iterator_result_typmod);
  
  		/* In slice case, value is temporary; must free it to avoid leakage */
  		if (stmt->slice > 0)
  			pfree(DatumGetPointer(value));
  
  		/*
  		 * Execute the statements
  		 */
  		rc = exec_stmts(estate, stmt->body);
  
  		LOOP_RC_PROCESSING(stmt->label, break);
  
  		MemoryContextSwitchTo(stmt_mcontext);
  	}
  
  	/* Restore memory context state */
  	MemoryContextSwitchTo(oldcontext);
  	pop_stmt_mcontext(estate);
  
  	/* Release temporary memory, including the array value */
  	MemoryContextReset(stmt_mcontext);
  
  	/*
  	 * Set the FOUND variable to indicate the result of executing the loop
  	 * (namely, whether we looped one or more times). This must be set here so
  	 * that it does not interfere with the value of the FOUND variable inside
  	 * the loop processing itself.
  	 */
  	exec_set_found(estate, found);
  
  	return rc;
  }
  
  
  /* ----------
   * exec_stmt_exit			Implements EXIT and CONTINUE
   *
   * This begins the process of exiting / restarting a loop.
   * ----------
   */
  static int
  exec_stmt_exit(PLpgSQL_execstate *estate, PLpgSQL_stmt_exit *stmt)
  {
  	/*
  	 * If the exit / continue has a condition, evaluate it
  	 */
  	if (stmt->cond != NULL)
  	{
  		bool		value;
  		bool		isnull;
  
  		value = exec_eval_boolean(estate, stmt->cond, &isnull);
  		exec_eval_cleanup(estate);
  		if (isnull || value == false)
  			return PLPGSQL_RC_OK;
  	}
  
  	estate->exitlabel = stmt->label;
  	if (stmt->is_exit)
  		return PLPGSQL_RC_EXIT;
  	else
  		return PLPGSQL_RC_CONTINUE;
  }
  
  
  /* ----------
   * exec_stmt_return			Evaluate an expression and start
   *					returning from the function.
   *
   * Note: The result may be in the eval_mcontext.  Therefore, we must not
   * do exec_eval_cleanup while unwinding the control stack.
   * ----------
   */
  static int
  exec_stmt_return(PLpgSQL_execstate *estate, PLpgSQL_stmt_return *stmt)
  {
  	/*
  	 * If processing a set-returning PL/pgSQL function, the final RETURN
  	 * indicates that the function is finished producing tuples.  The rest of
  	 * the work will be done at the top level.
  	 */
  	if (estate->retisset)
  		return PLPGSQL_RC_RETURN;
  
  	/* initialize for null result */
  	estate->retval = (Datum) 0;
  	estate->retisnull = true;
  	estate->rettype = InvalidOid;
  
  	/*
  	 * Special case path when the RETURN expression is a simple variable
  	 * reference; in particular, this path is always taken in functions with
  	 * one or more OUT parameters.
  	 *
  	 * This special case is especially efficient for returning variables that
  	 * have R/W expanded values: we can put the R/W pointer directly into
  	 * estate->retval, leading to transferring the value to the caller's
  	 * context cheaply.  If we went through exec_eval_expr we'd end up with a
  	 * R/O pointer.  It's okay to skip MakeExpandedObjectReadOnly here since
  	 * we know we won't need the variable's value within the function anymore.
  	 */
  	if (stmt->retvarno >= 0)
  	{
  		PLpgSQL_datum *retvar = estate->datums[stmt->retvarno];
  
  		switch (retvar->dtype)
  		{
  			case PLPGSQL_DTYPE_PROMISE:
  				/* fulfill promise if needed, then handle like regular var */
  				plpgsql_fulfill_promise(estate, (PLpgSQL_var *) retvar);
  
  				/* FALL THRU */
  
  			case PLPGSQL_DTYPE_VAR:
  				{
  					PLpgSQL_var *var = (PLpgSQL_var *) retvar;
  
  					estate->retval = var->value;
  					estate->retisnull = var->isnull;
  					estate->rettype = var->datatype->typoid;
  
  					/*
  					 * A PLpgSQL_var could not be of composite type, so
  					 * conversion must fail if retistuple.  We throw a custom
  					 * error mainly for consistency with historical behavior.
  					 * For the same reason, we don't throw error if the result
  					 * is NULL.  (Note that plpgsql_exec_trigger assumes that
  					 * any non-null result has been verified to be composite.)
  					 */
  					if (estate->retistuple && !estate->retisnull)
  						ereport(ERROR,
  								(errcode(ERRCODE_DATATYPE_MISMATCH),
  								 errmsg("cannot return non-composite value from function returning composite type")));
  				}
  				break;
  
  			case PLPGSQL_DTYPE_REC:
  				{
  					PLpgSQL_rec *rec = (PLpgSQL_rec *) retvar;
  
  					/* If record is empty, we return NULL not a row of nulls */
  					if (rec->erh && !ExpandedRecordIsEmpty(rec->erh))
  					{
  						estate->retval = ExpandedRecordGetDatum(rec->erh);
  						estate->retisnull = false;
  						estate->rettype = rec->rectypeid;
  					}
  				}
  				break;
  
  			case PLPGSQL_DTYPE_ROW:
  				{
  					PLpgSQL_row *row = (PLpgSQL_row *) retvar;
  					int32		rettypmod;
  
  					/* We get here if there are multiple OUT parameters */
  					exec_eval_datum(estate,
  									(PLpgSQL_datum *) row,
  									&estate->rettype,
  									&rettypmod,
  									&estate->retval,
  									&estate->retisnull);
  				}
  				break;
  
  			default:
  				elog(ERROR, "unrecognized dtype: %d", retvar->dtype);
  		}
  
  		return PLPGSQL_RC_RETURN;
  	}
  
  	if (stmt->expr != NULL)
  	{
  		int32		rettypmod;
  
  		estate->retval = exec_eval_expr(estate, stmt->expr,
  										&(estate->retisnull),
  										&(estate->rettype),
  										&rettypmod);
  
  		/*
  		 * As in the DTYPE_VAR case above, throw a custom error if a non-null,
  		 * non-composite value is returned in a function returning tuple.
  		 */
  		if (estate->retistuple && !estate->retisnull &&
  			!type_is_rowtype(estate->rettype))
  			ereport(ERROR,
  					(errcode(ERRCODE_DATATYPE_MISMATCH),
  					 errmsg("cannot return non-composite value from function returning composite type")));
  
  		return PLPGSQL_RC_RETURN;
  	}
  
  	/*
  	 * Special hack for function returning VOID: instead of NULL, return a
  	 * non-null VOID value.  This is of dubious importance but is kept for
  	 * backwards compatibility.  We don't do it for procedures, though.
  	 */
  	if (estate->fn_rettype == VOIDOID &&
  		estate->func->fn_prokind != PROKIND_PROCEDURE)
  	{
  		estate->retval = (Datum) 0;
  		estate->retisnull = false;
  		estate->rettype = VOIDOID;
  	}
  
  	return PLPGSQL_RC_RETURN;
  }
  
  /* ----------
   * exec_stmt_return_next		Evaluate an expression and add it to the
   *								list of tuples returned by the current
   *								SRF.
   * ----------
   */
  static int
  exec_stmt_return_next(PLpgSQL_execstate *estate,
  					  PLpgSQL_stmt_return_next *stmt)
  {
  	TupleDesc	tupdesc;
  	int			natts;
  	HeapTuple	tuple;
  	MemoryContext oldcontext;
  
  	if (!estate->retisset)
  		ereport(ERROR,
  				(errcode(ERRCODE_SYNTAX_ERROR),
  				 errmsg("cannot use RETURN NEXT in a non-SETOF function")));
  
  	if (estate->tuple_store == NULL)
  		exec_init_tuple_store(estate);
  
  	/* tuple_store_desc will be filled by exec_init_tuple_store */
  	tupdesc = estate->tuple_store_desc;
  	natts = tupdesc->natts;
  
  	/*
  	 * Special case path when the RETURN NEXT expression is a simple variable
  	 * reference; in particular, this path is always taken in functions with
  	 * one or more OUT parameters.
  	 *
  	 * Unlike exec_stmt_return, there's no special win here for R/W expanded
  	 * values, since they'll have to get flattened to go into the tuplestore.
  	 * Indeed, we'd better make them R/O to avoid any risk of the casting step
  	 * changing them in-place.
  	 */
  	if (stmt->retvarno >= 0)
  	{
  		PLpgSQL_datum *retvar = estate->datums[stmt->retvarno];
  
  		switch (retvar->dtype)
  		{
  			case PLPGSQL_DTYPE_PROMISE:
  				/* fulfill promise if needed, then handle like regular var */
  				plpgsql_fulfill_promise(estate, (PLpgSQL_var *) retvar);
  
  				/* FALL THRU */
  
  			case PLPGSQL_DTYPE_VAR:
  				{
  					PLpgSQL_var *var = (PLpgSQL_var *) retvar;
  					Datum		retval = var->value;
  					bool		isNull = var->isnull;
  					Form_pg_attribute attr = TupleDescAttr(tupdesc, 0);
  
  					if (natts != 1)
  						ereport(ERROR,
  								(errcode(ERRCODE_DATATYPE_MISMATCH),
  								 errmsg("wrong result type supplied in RETURN NEXT")));
  
  					/* let's be very paranoid about the cast step */
  					retval = MakeExpandedObjectReadOnly(retval,
  														isNull,
  														var->datatype->typlen);
  
  					/* coerce type if needed */
  					retval = exec_cast_value(estate,
  											 retval,
  											 &isNull,
  											 var->datatype->typoid,
  											 var->datatype->atttypmod,
  											 attr->atttypid,
  											 attr->atttypmod);
  
  					tuplestore_putvalues(estate->tuple_store, tupdesc,
  										 &retval, &isNull);
  				}
  				break;
  
  			case PLPGSQL_DTYPE_REC:
  				{
  					PLpgSQL_rec *rec = (PLpgSQL_rec *) retvar;
  					TupleDesc	rec_tupdesc;
  					TupleConversionMap *tupmap;
  
  					/* If rec is null, try to convert it to a row of nulls */
  					if (rec->erh == NULL)
  						instantiate_empty_record_variable(estate, rec);
  					if (ExpandedRecordIsEmpty(rec->erh))
  						deconstruct_expanded_record(rec->erh);
  
  					/* Use eval_mcontext for tuple conversion work */
  					oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate));
  					rec_tupdesc = expanded_record_get_tupdesc(rec->erh);
  					tupmap = convert_tuples_by_position(rec_tupdesc,
  														tupdesc,
  														gettext_noop("wrong record type supplied in RETURN NEXT"));
  					tuple = expanded_record_get_tuple(rec->erh);
  					if (tupmap)
  						tuple = execute_attr_map_tuple(tuple, tupmap);
  					tuplestore_puttuple(estate->tuple_store, tuple);
  					MemoryContextSwitchTo(oldcontext);
  				}
  				break;
  
  			case PLPGSQL_DTYPE_ROW:
  				{
  					PLpgSQL_row *row = (PLpgSQL_row *) retvar;
  
  					/* We get here if there are multiple OUT parameters */
  
  					/* Use eval_mcontext for tuple conversion work */
  					oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate));
  					tuple = make_tuple_from_row(estate, row, tupdesc);
  					if (tuple == NULL)	/* should not happen */
  						ereport(ERROR,
  								(errcode(ERRCODE_DATATYPE_MISMATCH),
  								 errmsg("wrong record type supplied in RETURN NEXT")));
  					tuplestore_puttuple(estate->tuple_store, tuple);
  					MemoryContextSwitchTo(oldcontext);
  				}
  				break;
  
  			default:
  				elog(ERROR, "unrecognized dtype: %d", retvar->dtype);
  				break;
  		}
  	}
  	else if (stmt->expr)
  	{
  		Datum		retval;
  		bool		isNull;
  		Oid			rettype;
  		int32		rettypmod;
  
  		retval = exec_eval_expr(estate,
  								stmt->expr,
  								&isNull,
  								&rettype,
  								&rettypmod);
  
  		if (estate->retistuple)
  		{
  			/* Expression should be of RECORD or composite type */
  			if (!isNull)
  			{
  				HeapTupleData tmptup;
  				TupleDesc	retvaldesc;
  				TupleConversionMap *tupmap;
  
  				if (!type_is_rowtype(rettype))
  					ereport(ERROR,
  							(errcode(ERRCODE_DATATYPE_MISMATCH),
  							 errmsg("cannot return non-composite value from function returning composite type")));
  
  				/* Use eval_mcontext for tuple conversion work */
  				oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate));
  				retvaldesc = deconstruct_composite_datum(retval, &tmptup);
  				tuple = &tmptup;
  				tupmap = convert_tuples_by_position(retvaldesc, tupdesc,
  													gettext_noop("returned record type does not match expected record type"));
  				if (tupmap)
  					tuple = execute_attr_map_tuple(tuple, tupmap);
  				tuplestore_puttuple(estate->tuple_store, tuple);
  				ReleaseTupleDesc(retvaldesc);
  				MemoryContextSwitchTo(oldcontext);
  			}
  			else
  			{
  				/* Composite NULL --- store a row of nulls */
  				Datum	   *nulldatums;
  				bool	   *nullflags;
  
  				nulldatums = (Datum *)
  					eval_mcontext_alloc0(estate, natts * sizeof(Datum));
  				nullflags = (bool *)
  					eval_mcontext_alloc(estate, natts * sizeof(bool));
  				memset(nullflags, true, natts * sizeof(bool));
  				tuplestore_putvalues(estate->tuple_store, tupdesc,
  									 nulldatums, nullflags);
  			}
  		}
  		else
  		{
  			Form_pg_attribute attr = TupleDescAttr(tupdesc, 0);
  
  			/* Simple scalar result */
  			if (natts != 1)
  				ereport(ERROR,
  						(errcode(ERRCODE_DATATYPE_MISMATCH),
  						 errmsg("wrong result type supplied in RETURN NEXT")));
  
  			/* coerce type if needed */
  			retval = exec_cast_value(estate,
  									 retval,
  									 &isNull,
  									 rettype,
  									 rettypmod,
  									 attr->atttypid,
  									 attr->atttypmod);
  
  			tuplestore_putvalues(estate->tuple_store, tupdesc,
  								 &retval, &isNull);
  		}
  	}
  	else
  	{
  		ereport(ERROR,
  				(errcode(ERRCODE_SYNTAX_ERROR),
  				 errmsg("RETURN NEXT must have a parameter")));
  	}
  
  	exec_eval_cleanup(estate);
  
  	return PLPGSQL_RC_OK;
  }
  
  /* ----------
   * exec_stmt_return_query		Evaluate a query and add it to the
   *								list of tuples returned by the current
   *								SRF.
   * ----------
   */
  static int
  exec_stmt_return_query(PLpgSQL_execstate *estate,
  					   PLpgSQL_stmt_return_query *stmt)
  {
  	Portal		portal;
  	uint64		processed = 0;
  	TupleConversionMap *tupmap;
  	MemoryContext oldcontext;
  
  	if (!estate->retisset)
  		ereport(ERROR,
  				(errcode(ERRCODE_SYNTAX_ERROR),
  				 errmsg("cannot use RETURN QUERY in a non-SETOF function")));
  
  	if (estate->tuple_store == NULL)
  		exec_init_tuple_store(estate);
  
  	if (stmt->query != NULL)
  	{
  		/* static query */
  		exec_run_select(estate, stmt->query, 0, &portal);
  	}
  	else
  	{
  		/* RETURN QUERY EXECUTE */
  		Assert(stmt->dynquery != NULL);
  		portal = exec_dynquery_with_params(estate, stmt->dynquery,
  										   stmt->params, NULL,
  										   0);
  	}
  
  	/* Use eval_mcontext for tuple conversion work */
  	oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate));
  
  	tupmap = convert_tuples_by_position(portal->tupDesc,
  										estate->tuple_store_desc,
  										gettext_noop("structure of query does not match function result type"));
  
  	while (true)
  	{
  		uint64		i;
  
  		SPI_cursor_fetch(portal, true, 50);
  
  		/* SPI will have changed CurrentMemoryContext */
  		MemoryContextSwitchTo(get_eval_mcontext(estate));
  
  		if (SPI_processed == 0)
  			break;
  
  		for (i = 0; i < SPI_processed; i++)
  		{
  			HeapTuple	tuple = SPI_tuptable->vals[i];
  
  			if (tupmap)
  				tuple = execute_attr_map_tuple(tuple, tupmap);
  			tuplestore_puttuple(estate->tuple_store, tuple);
  			if (tupmap)
  				heap_freetuple(tuple);
  			processed++;
  		}
  
  		SPI_freetuptable(SPI_tuptable);
  	}
  
  	SPI_freetuptable(SPI_tuptable);
  	SPI_cursor_close(portal);
  
  	MemoryContextSwitchTo(oldcontext);
  	exec_eval_cleanup(estate);
  
  	estate->eval_processed = processed;
  	exec_set_found(estate, processed != 0);
  
  	return PLPGSQL_RC_OK;
  }
  
  static void
  exec_init_tuple_store(PLpgSQL_execstate *estate)
  {
  	ReturnSetInfo *rsi = estate->rsi;
  	MemoryContext oldcxt;
  	ResourceOwner oldowner;
  
  	/*
  	 * Check caller can handle a set result in the way we want
  	 */
  	if (!rsi || !IsA(rsi, ReturnSetInfo) ||
  		(rsi->allowedModes & SFRM_Materialize) == 0 ||
  		rsi->expectedDesc == NULL)
  		ereport(ERROR,
  				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  				 errmsg("set-valued function called in context that cannot accept a set")));
  
  	/*
  	 * Switch to the right memory context and resource owner for storing the
  	 * tuplestore for return set. If we're within a subtransaction opened for
  	 * an exception-block, for example, we must still create the tuplestore in
  	 * the resource owner that was active when this function was entered, and
  	 * not in the subtransaction resource owner.
  	 */
  	oldcxt = MemoryContextSwitchTo(estate->tuple_store_cxt);
  	oldowner = CurrentResourceOwner;
  	CurrentResourceOwner = estate->tuple_store_owner;
  
  	estate->tuple_store =
  		tuplestore_begin_heap(rsi->allowedModes & SFRM_Materialize_Random,
  							  false, work_mem);
  
  	CurrentResourceOwner = oldowner;
  	MemoryContextSwitchTo(oldcxt);
  
  	estate->tuple_store_desc = rsi->expectedDesc;
  }
  
  #define SET_RAISE_OPTION_TEXT(opt, name) \
  do { \
  	if (opt) \
  		ereport(ERROR, \
  				(errcode(ERRCODE_SYNTAX_ERROR), \
  				 errmsg("RAISE option already specified: %s", \
  						name))); \
  	opt = MemoryContextStrdup(stmt_mcontext, extval); \
  } while (0)
  
  /* ----------
   * exec_stmt_raise			Build a message and throw it with elog()
   * ----------
   */
  static int
  exec_stmt_raise(PLpgSQL_execstate *estate, PLpgSQL_stmt_raise *stmt)
  {
  	int			err_code = 0;
  	char	   *condname = NULL;
  	char	   *err_message = NULL;
  	char	   *err_detail = NULL;
  	char	   *err_hint = NULL;
  	char	   *err_column = NULL;
  	char	   *err_constraint = NULL;
  	char	   *err_datatype = NULL;
  	char	   *err_table = NULL;
  	char	   *err_schema = NULL;
  	MemoryContext stmt_mcontext;
  	ListCell   *lc;
  
  	/* RAISE with no parameters: re-throw current exception */
  	if (stmt->condname == NULL && stmt->message == NULL &&
  		stmt->options == NIL)
  	{
  		if (estate->cur_error != NULL)
  			ReThrowError(estate->cur_error);
  		/* oops, we're not inside a handler */
  		ereport(ERROR,
  				(errcode(ERRCODE_STACKED_DIAGNOSTICS_ACCESSED_WITHOUT_ACTIVE_HANDLER),
  				 errmsg("RAISE without parameters cannot be used outside an exception handler")));
  	}
  
  	/* We'll need to accumulate the various strings in stmt_mcontext */
  	stmt_mcontext = get_stmt_mcontext(estate);
  
  	if (stmt->condname)
  	{
  		err_code = plpgsql_recognize_err_condition(stmt->condname, true);
  		condname = MemoryContextStrdup(stmt_mcontext, stmt->condname);
  	}
  
  	if (stmt->message)
  	{
  		StringInfoData ds;
  		ListCell   *current_param;
  		char	   *cp;
  		MemoryContext oldcontext;
  
  		/* build string in stmt_mcontext */
  		oldcontext = MemoryContextSwitchTo(stmt_mcontext);
  		initStringInfo(&ds);
  		MemoryContextSwitchTo(oldcontext);
  
  		current_param = list_head(stmt->params);
  
  		for (cp = stmt->message; *cp; cp++)
  		{
  			/*
  			 * Occurrences of a single % are replaced by the next parameter's
  			 * external representation. Double %'s are converted to one %.
  			 */
  			if (cp[0] == '%')
  			{
  				Oid			paramtypeid;
  				int32		paramtypmod;
  				Datum		paramvalue;
  				bool		paramisnull;
  				char	   *extval;
  
  				if (cp[1] == '%')
  				{
  					appendStringInfoChar(&ds, '%');
  					cp++;
  					continue;
  				}
  
  				/* should have been checked at compile time */
  				if (current_param == NULL)
  					elog(ERROR, "unexpected RAISE parameter list length");
  
  				paramvalue = exec_eval_expr(estate,
  											(PLpgSQL_expr *) lfirst(current_param),
  											&paramisnull,
  											&paramtypeid,
  											&paramtypmod);
  
  				if (paramisnull)
  					extval = "<NULL>";
  				else
  					extval = convert_value_to_string(estate,
  													 paramvalue,
  													 paramtypeid);
  				appendStringInfoString(&ds, extval);
  				current_param = lnext(stmt->params, current_param);
  				exec_eval_cleanup(estate);
  			}
  			else
  				appendStringInfoChar(&ds, cp[0]);
  		}
  
  		/* should have been checked at compile time */
  		if (current_param != NULL)
  			elog(ERROR, "unexpected RAISE parameter list length");
  
  		err_message = ds.data;
  	}
  
  	foreach(lc, stmt->options)
  	{
  		PLpgSQL_raise_option *opt = (PLpgSQL_raise_option *) lfirst(lc);
  		Datum		optionvalue;
  		bool		optionisnull;
  		Oid			optiontypeid;
  		int32		optiontypmod;
  		char	   *extval;
  
  		optionvalue = exec_eval_expr(estate, opt->expr,
  									 &optionisnull,
  									 &optiontypeid,
  									 &optiontypmod);
  		if (optionisnull)
  			ereport(ERROR,
  					(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
  					 errmsg("RAISE statement option cannot be null")));
  
  		extval = convert_value_to_string(estate, optionvalue, optiontypeid);
  
  		switch (opt->opt_type)
  		{
  			case PLPGSQL_RAISEOPTION_ERRCODE:
  				if (err_code)
  					ereport(ERROR,
  							(errcode(ERRCODE_SYNTAX_ERROR),
  							 errmsg("RAISE option already specified: %s",
  									"ERRCODE")));
  				err_code = plpgsql_recognize_err_condition(extval, true);
  				condname = MemoryContextStrdup(stmt_mcontext, extval);
  				break;
  			case PLPGSQL_RAISEOPTION_MESSAGE:
  				SET_RAISE_OPTION_TEXT(err_message, "MESSAGE");
  				break;
  			case PLPGSQL_RAISEOPTION_DETAIL:
  				SET_RAISE_OPTION_TEXT(err_detail, "DETAIL");
  				break;
  			case PLPGSQL_RAISEOPTION_HINT:
  				SET_RAISE_OPTION_TEXT(err_hint, "HINT");
  				break;
  			case PLPGSQL_RAISEOPTION_COLUMN:
  				SET_RAISE_OPTION_TEXT(err_column, "COLUMN");
  				break;
  			case PLPGSQL_RAISEOPTION_CONSTRAINT:
  				SET_RAISE_OPTION_TEXT(err_constraint, "CONSTRAINT");
  				break;
  			case PLPGSQL_RAISEOPTION_DATATYPE:
  				SET_RAISE_OPTION_TEXT(err_datatype, "DATATYPE");
  				break;
  			case PLPGSQL_RAISEOPTION_TABLE:
  				SET_RAISE_OPTION_TEXT(err_table, "TABLE");
  				break;
  			case PLPGSQL_RAISEOPTION_SCHEMA:
  				SET_RAISE_OPTION_TEXT(err_schema, "SCHEMA");
  				break;
  			default:
  				elog(ERROR, "unrecognized raise option: %d", opt->opt_type);
  		}
  
  		exec_eval_cleanup(estate);
  	}
  
  	/* Default code if nothing specified */
  	if (err_code == 0 && stmt->elog_level >= ERROR)
  		err_code = ERRCODE_RAISE_EXCEPTION;
  
  	/* Default error message if nothing specified */
  	if (err_message == NULL)
  	{
  		if (condname)
  		{
  			err_message = condname;
  			condname = NULL;
  		}
  		else
  			err_message = MemoryContextStrdup(stmt_mcontext,
  											  unpack_sql_state(err_code));
  	}
  
  	/*
  	 * Throw the error (may or may not come back)
  	 */
  	ereport(stmt->elog_level,
  			(err_code ? errcode(err_code) : 0,
  			 errmsg_internal("%s", err_message),
  			 (err_detail != NULL) ? errdetail_internal("%s", err_detail) : 0,
  			 (err_hint != NULL) ? errhint("%s", err_hint) : 0,
  			 (err_column != NULL) ?
  			 err_generic_string(PG_DIAG_COLUMN_NAME, err_column) : 0,
  			 (err_constraint != NULL) ?
  			 err_generic_string(PG_DIAG_CONSTRAINT_NAME, err_constraint) : 0,
  			 (err_datatype != NULL) ?
  			 err_generic_string(PG_DIAG_DATATYPE_NAME, err_datatype) : 0,
  			 (err_table != NULL) ?
  			 err_generic_string(PG_DIAG_TABLE_NAME, err_table) : 0,
  			 (err_schema != NULL) ?
  			 err_generic_string(PG_DIAG_SCHEMA_NAME, err_schema) : 0));
  
  	/* Clean up transient strings */
  	MemoryContextReset(stmt_mcontext);
  
  	return PLPGSQL_RC_OK;
  }
  
  /* ----------
   * exec_stmt_assert			Assert statement
   * ----------
   */
  static int
  exec_stmt_assert(PLpgSQL_execstate *estate, PLpgSQL_stmt_assert *stmt)
  {
  	bool		value;
  	bool		isnull;
  
  	/* do nothing when asserts are not enabled */
  	if (!plpgsql_check_asserts)
  		return PLPGSQL_RC_OK;
  
  	value = exec_eval_boolean(estate, stmt->cond, &isnull);
  	exec_eval_cleanup(estate);
  
  	if (isnull || !value)
  	{
  		char	   *message = NULL;
  
  		if (stmt->message != NULL)
  		{
  			Datum		val;
  			Oid			typeid;
  			int32		typmod;
  
  			val = exec_eval_expr(estate, stmt->message,
  								 &isnull, &typeid, &typmod);
  			if (!isnull)
  				message = convert_value_to_string(estate, val, typeid);
  			/* we mustn't do exec_eval_cleanup here */
  		}
  
  		ereport(ERROR,
  				(errcode(ERRCODE_ASSERT_FAILURE),
  				 message ? errmsg_internal("%s", message) :
  				 errmsg("assertion failed")));
  	}
  
  	return PLPGSQL_RC_OK;
  }
  
  /* ----------
   * Initialize a mostly empty execution state
   * ----------
   */
  static void
  plpgsql_estate_setup(PLpgSQL_execstate *estate,
  					 PLpgSQL_function *func,
  					 ReturnSetInfo *rsi,
  					 EState *simple_eval_estate)
  {
  	HASHCTL		ctl;
  
  	/* this link will be restored at exit from plpgsql_call_handler */
  	func->cur_estate = estate;
  
  	estate->func = func;
  	estate->trigdata = NULL;
  	estate->evtrigdata = NULL;
  
  	estate->retval = (Datum) 0;
  	estate->retisnull = true;
  	estate->rettype = InvalidOid;
  
  	estate->fn_rettype = func->fn_rettype;
  	estate->retistuple = func->fn_retistuple;
  	estate->retisset = func->fn_retset;
  
  	estate->readonly_func = func->fn_readonly;
  	estate->atomic = true;
  
  	estate->exitlabel = NULL;
  	estate->cur_error = NULL;
  
  	estate->tuple_store = NULL;
  	estate->tuple_store_desc = NULL;
  	if (rsi)
  	{
  		estate->tuple_store_cxt = rsi->econtext->ecxt_per_query_memory;
  		estate->tuple_store_owner = CurrentResourceOwner;
  	}
  	else
  	{
  		estate->tuple_store_cxt = NULL;
  		estate->tuple_store_owner = NULL;
  	}
  	estate->rsi = rsi;
  
  	estate->found_varno = func->found_varno;
  	estate->ndatums = func->ndatums;
  	estate->datums = NULL;
  	/* the datums array will be filled by copy_plpgsql_datums() */
  	estate->datum_context = CurrentMemoryContext;
  
  	/* initialize our ParamListInfo with appropriate hook functions */
  	estate->paramLI = makeParamList(0);
  	estate->paramLI->paramFetch = plpgsql_param_fetch;
  	estate->paramLI->paramFetchArg = (void *) estate;
  	estate->paramLI->paramCompile = plpgsql_param_compile;
  	estate->paramLI->paramCompileArg = NULL;	/* not needed */
  	estate->paramLI->parserSetup = (ParserSetupHook) plpgsql_parser_setup;
  	estate->paramLI->parserSetupArg = NULL; /* filled during use */
  	estate->paramLI->numParams = estate->ndatums;
  
  	/* set up for use of appropriate simple-expression EState and cast hash */
  	if (simple_eval_estate)
  	{
  		estate->simple_eval_estate = simple_eval_estate;
  		/* Private cast hash just lives in function's main context */
  		memset(&ctl, 0, sizeof(ctl));
  		ctl.keysize = sizeof(plpgsql_CastHashKey);
  		ctl.entrysize = sizeof(plpgsql_CastHashEntry);
  		ctl.hcxt = CurrentMemoryContext;
  		estate->cast_hash = hash_create("PLpgSQL private cast cache",
  										16, /* start small and extend */
  										&ctl,
  										HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
  		estate->cast_hash_context = CurrentMemoryContext;
  	}
  	else
  	{
  		estate->simple_eval_estate = shared_simple_eval_estate;
  		/* Create the session-wide cast-info hash table if we didn't already */
  		if (shared_cast_hash == NULL)
  		{
  			shared_cast_context = AllocSetContextCreate(TopMemoryContext,
  														"PLpgSQL cast info",
  														ALLOCSET_DEFAULT_SIZES);
  			memset(&ctl, 0, sizeof(ctl));
  			ctl.keysize = sizeof(plpgsql_CastHashKey);
  			ctl.entrysize = sizeof(plpgsql_CastHashEntry);
  			ctl.hcxt = shared_cast_context;
  			shared_cast_hash = hash_create("PLpgSQL cast cache",
  										   16,	/* start small and extend */
  										   &ctl,
  										   HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
  		}
  		estate->cast_hash = shared_cast_hash;
  		estate->cast_hash_context = shared_cast_context;
  	}
  
  	/*
  	 * We start with no stmt_mcontext; one will be created only if needed.
  	 * That context will be a direct child of the function's main execution
  	 * context.  Additional stmt_mcontexts might be created as children of it.
  	 */
  	estate->stmt_mcontext = NULL;
  	estate->stmt_mcontext_parent = CurrentMemoryContext;
  
  	estate->eval_tuptable = NULL;
  	estate->eval_processed = 0;
  	estate->eval_econtext = NULL;
  
  	estate->err_stmt = NULL;
  	estate->err_text = NULL;
  
  	estate->plugin_info = NULL;
  
  	/*
  	 * Create an EState and ExprContext for evaluation of simple expressions.
  	 */
  	plpgsql_create_econtext(estate);
  
  	/*
  	 * Let the plugin see this function before we initialize any local
  	 * PL/pgSQL variables - note that we also give the plugin a few function
  	 * pointers so it can call back into PL/pgSQL for doing things like
  	 * variable assignments and stack traces
  	 */
  	if (*plpgsql_plugin_ptr)
  	{
  		(*plpgsql_plugin_ptr)->error_callback = plpgsql_exec_error_callback;
  		(*plpgsql_plugin_ptr)->assign_expr = exec_assign_expr;
  
  		if ((*plpgsql_plugin_ptr)->func_setup)
  			((*plpgsql_plugin_ptr)->func_setup) (estate, func);
  	}
  }
  
  /* ----------
   * Release temporary memory used by expression/subselect evaluation
   *
   * NB: the result of the evaluation is no longer valid after this is done,
   * unless it is a pass-by-value datatype.
   *
   * NB: if you change this code, see also the hacks in exec_assign_value's
   * PLPGSQL_DTYPE_ARRAYELEM case for partial cleanup after subscript evals.
   * ----------
   */
  static void
  exec_eval_cleanup(PLpgSQL_execstate *estate)
  {
  	/* Clear result of a full SPI_execute */
  	if (estate->eval_tuptable != NULL)
  		SPI_freetuptable(estate->eval_tuptable);
  	estate->eval_tuptable = NULL;
  
  	/*
  	 * Clear result of exec_eval_simple_expr (but keep the econtext).  This
  	 * also clears any short-lived allocations done via get_eval_mcontext.
  	 */
  	if (estate->eval_econtext != NULL)
  		ResetExprContext(estate->eval_econtext);
  }
  
  
  /* ----------
   * Generate a prepared plan
   * ----------
   */
  static void
  exec_prepare_plan(PLpgSQL_execstate *estate,
  				  PLpgSQL_expr *expr, int cursorOptions,
  				  bool keepplan)
  {
  	SPIPlanPtr	plan;
  
  	/*
  	 * The grammar can't conveniently set expr->func while building the parse
  	 * tree, so make sure it's set before parser hooks need it.
  	 */
  	expr->func = estate->func;
  
  	/*
  	 * Generate and save the plan
  	 */
  	plan = SPI_prepare_params(expr->query,
  							  (ParserSetupHook) plpgsql_parser_setup,
  							  (void *) expr,
  							  cursorOptions);
  	if (plan == NULL)
  		elog(ERROR, "SPI_prepare_params failed for \"%s\": %s",
  			 expr->query, SPI_result_code_string(SPI_result));
  	if (keepplan)
  		SPI_keepplan(plan);
  	expr->plan = plan;
  
  	/* Check to see if it's a simple expression */
  	exec_simple_check_plan(estate, expr);
  
  	/*
  	 * Mark expression as not using a read-write param.  exec_assign_value has
  	 * to take steps to override this if appropriate; that seems cleaner than
  	 * adding parameters to all other callers.
  	 */
  	expr->rwparam = -1;
  }
  
  
  /* ----------
   * exec_stmt_execsql			Execute an SQL statement (possibly with INTO).
   *
   * Note: some callers rely on this not touching stmt_mcontext.  If it ever
   * needs to use that, fix those callers to push/pop stmt_mcontext.
   * ----------
   */
  static int
  exec_stmt_execsql(PLpgSQL_execstate *estate,
  				  PLpgSQL_stmt_execsql *stmt)
  {
  	ParamListInfo paramLI;
  	long		tcount;
  	int			rc;
  	PLpgSQL_expr *expr = stmt->sqlstmt;
  	int			too_many_rows_level = 0;
  
  	if (plpgsql_extra_errors & PLPGSQL_XCHECK_TOOMANYROWS)
  		too_many_rows_level = ERROR;
  	else if (plpgsql_extra_warnings & PLPGSQL_XCHECK_TOOMANYROWS)
  		too_many_rows_level = WARNING;
  
  	/*
  	 * On the first call for this statement generate the plan, and detect
  	 * whether the statement is INSERT/UPDATE/DELETE
  	 */
  	if (expr->plan == NULL)
  	{
  		ListCell   *l;
  
  		exec_prepare_plan(estate, expr, CURSOR_OPT_PARALLEL_OK, true);
  		stmt->mod_stmt = false;
  		foreach(l, SPI_plan_get_plan_sources(expr->plan))
  		{
  			CachedPlanSource *plansource = (CachedPlanSource *) lfirst(l);
  
  			/*
  			 * We could look at the raw_parse_tree, but it seems simpler to
  			 * check the command tag.  Note we should *not* look at the Query
  			 * tree(s), since those are the result of rewriting and could have
  			 * been transmogrified into something else entirely.
  			 */
  			if (plansource->commandTag &&
  				(strcmp(plansource->commandTag, "INSERT") == 0 ||
  				 strcmp(plansource->commandTag, "UPDATE") == 0 ||
  				 strcmp(plansource->commandTag, "DELETE") == 0))
  			{
  				stmt->mod_stmt = true;
  				break;
  			}
  		}
  	}
  
  	/*
  	 * Set up ParamListInfo to pass to executor
  	 */
  	paramLI = setup_param_list(estate, expr);
  
  	/*
  	 * If we have INTO, then we only need one row back ... but if we have INTO
  	 * STRICT or extra check too_many_rows, ask for two rows, so that we can
  	 * verify the statement returns only one.  INSERT/UPDATE/DELETE are always
  	 * treated strictly. Without INTO, just run the statement to completion
  	 * (tcount = 0).
  	 *
  	 * We could just ask for two rows always when using INTO, but there are
  	 * some cases where demanding the extra row costs significant time, eg by
  	 * forcing completion of a sequential scan.  So don't do it unless we need
  	 * to enforce strictness.
  	 */
  	if (stmt->into)
  	{
  		if (stmt->strict || stmt->mod_stmt || too_many_rows_level)
  			tcount = 2;
  		else
  			tcount = 1;
  	}
  	else
  		tcount = 0;
  
  	/*
  	 * Execute the plan
  	 */
  	rc = SPI_execute_plan_with_paramlist(expr->plan, paramLI,
  										 estate->readonly_func, tcount);
  
  	/*
  	 * Check for error, and set FOUND if appropriate (for historical reasons
  	 * we set FOUND only for certain query types).  Also Assert that we
  	 * identified the statement type the same as SPI did.
  	 */
  	switch (rc)
  	{
  		case SPI_OK_SELECT:
  			Assert(!stmt->mod_stmt);
  			exec_set_found(estate, (SPI_processed != 0));
  			break;
  
  		case SPI_OK_INSERT:
  		case SPI_OK_UPDATE:
  		case SPI_OK_DELETE:
  		case SPI_OK_INSERT_RETURNING:
  		case SPI_OK_UPDATE_RETURNING:
  		case SPI_OK_DELETE_RETURNING:
  			Assert(stmt->mod_stmt);
  			exec_set_found(estate, (SPI_processed != 0));
  			break;
  
  		case SPI_OK_SELINTO:
  		case SPI_OK_UTILITY:
  			Assert(!stmt->mod_stmt);
  			break;
  
  		case SPI_OK_REWRITTEN:
  
  			/*
  			 * The command was rewritten into another kind of command. It's
  			 * not clear what FOUND would mean in that case (and SPI doesn't
  			 * return the row count either), so just set it to false.  Note
  			 * that we can't assert anything about mod_stmt here.
  			 */
  			exec_set_found(estate, false);
  			break;
  
  			/* Some SPI errors deserve specific error messages */
  		case SPI_ERROR_COPY:
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("cannot COPY to/from client in PL/pgSQL")));
  			break;
  
  		case SPI_ERROR_TRANSACTION:
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("unsupported transaction command in PL/pgSQL")));
  			break;
  
  		default:
  			elog(ERROR, "SPI_execute_plan_with_paramlist failed executing query \"%s\": %s",
  				 expr->query, SPI_result_code_string(rc));
  			break;
  	}
  
  	/* All variants should save result info for GET DIAGNOSTICS */
  	estate->eval_processed = SPI_processed;
  
  	/* Process INTO if present */
  	if (stmt->into)
  	{
  		SPITupleTable *tuptab = SPI_tuptable;
  		uint64		n = SPI_processed;
  		PLpgSQL_variable *target;
  
  		/* If the statement did not return a tuple table, complain */
  		if (tuptab == NULL)
  			ereport(ERROR,
  					(errcode(ERRCODE_SYNTAX_ERROR),
  					 errmsg("INTO used with a command that cannot return data")));
  
  		/* Fetch target's datum entry */
  		target = (PLpgSQL_variable *) estate->datums[stmt->target->dno];
  
  		/*
  		 * If SELECT ... INTO specified STRICT, and the query didn't find
  		 * exactly one row, throw an error.  If STRICT was not specified, then
  		 * allow the query to find any number of rows.
  		 */
  		if (n == 0)
  		{
  			if (stmt->strict)
  			{
  				char	   *errdetail;
  
  				if (estate->func->print_strict_params)
  					errdetail = format_expr_params(estate, expr);
  				else
  					errdetail = NULL;
  
  				ereport(ERROR,
  						(errcode(ERRCODE_NO_DATA_FOUND),
  						 errmsg("query returned no rows"),
  						 errdetail ? errdetail_internal("parameters: %s", errdetail) : 0));
  			}
  			/* set the target to NULL(s) */
  			exec_move_row(estate, target, NULL, tuptab->tupdesc);
  		}
  		else
  		{
  			if (n > 1 && (stmt->strict || stmt->mod_stmt || too_many_rows_level))
  			{
  				char	   *errdetail;
  				int			errlevel;
  
  				if (estate->func->print_strict_params)
  					errdetail = format_expr_params(estate, expr);
  				else
  					errdetail = NULL;
  
  				errlevel = (stmt->strict || stmt->mod_stmt) ? ERROR : too_many_rows_level;
  
  				ereport(errlevel,
  						(errcode(ERRCODE_TOO_MANY_ROWS),
  						 errmsg("query returned more than one row"),
  						 errdetail ? errdetail_internal("parameters: %s", errdetail) : 0,
  						 errhint("Make sure the query returns a single row, or use LIMIT 1.")));
  			}
  			/* Put the first result row into the target */
  			exec_move_row(estate, target, tuptab->vals[0], tuptab->tupdesc);
  		}
  
  		/* Clean up */
  		exec_eval_cleanup(estate);
  		SPI_freetuptable(SPI_tuptable);
  	}
  	else
  	{
  		/* If the statement returned a tuple table, complain */
  		if (SPI_tuptable != NULL)
  			ereport(ERROR,
  					(errcode(ERRCODE_SYNTAX_ERROR),
  					 errmsg("query has no destination for result data"),
  					 (rc == SPI_OK_SELECT) ? errhint("If you want to discard the results of a SELECT, use PERFORM instead.") : 0));
  	}
  
  	return PLPGSQL_RC_OK;
  }
  
  
  /* ----------
   * exec_stmt_dynexecute			Execute a dynamic SQL query
   *					(possibly with INTO).
   * ----------
   */
  static int
  exec_stmt_dynexecute(PLpgSQL_execstate *estate,
  					 PLpgSQL_stmt_dynexecute *stmt)
  {
  	Datum		query;
  	bool		isnull;
  	Oid			restype;
  	int32		restypmod;
  	char	   *querystr;
  	int			exec_res;
  	PreparedParamsData *ppd = NULL;
  	MemoryContext stmt_mcontext = get_stmt_mcontext(estate);
  
  	/*
  	 * First we evaluate the string expression after the EXECUTE keyword. Its
  	 * result is the querystring we have to execute.
  	 */
  	query = exec_eval_expr(estate, stmt->query, &isnull, &restype, &restypmod);
  	if (isnull)
  		ereport(ERROR,
  				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
  				 errmsg("query string argument of EXECUTE is null")));
  
  	/* Get the C-String representation */
  	querystr = convert_value_to_string(estate, query, restype);
  
  	/* copy it into the stmt_mcontext before we clean up */
  	querystr = MemoryContextStrdup(stmt_mcontext, querystr);
  
  	exec_eval_cleanup(estate);
  
  	/*
  	 * Execute the query without preparing a saved plan.
  	 */
  	if (stmt->params)
  	{
  		ppd = exec_eval_using_params(estate, stmt->params);
  		exec_res = SPI_execute_with_args(querystr,
  										 ppd->nargs, ppd->types,
  										 ppd->values, ppd->nulls,
  										 estate->readonly_func, 0);
  	}
  	else
  		exec_res = SPI_execute(querystr, estate->readonly_func, 0);
  
  	switch (exec_res)
  	{
  		case SPI_OK_SELECT:
  		case SPI_OK_INSERT:
  		case SPI_OK_UPDATE:
  		case SPI_OK_DELETE:
  		case SPI_OK_INSERT_RETURNING:
  		case SPI_OK_UPDATE_RETURNING:
  		case SPI_OK_DELETE_RETURNING:
  		case SPI_OK_UTILITY:
  		case SPI_OK_REWRITTEN:
  			break;
  
  		case 0:
  
  			/*
  			 * Also allow a zero return, which implies the querystring
  			 * contained no commands.
  			 */
  			break;
  
  		case SPI_OK_SELINTO:
  
  			/*
  			 * We want to disallow SELECT INTO for now, because its behavior
  			 * is not consistent with SELECT INTO in a normal plpgsql context.
  			 * (We need to reimplement EXECUTE to parse the string as a
  			 * plpgsql command, not just feed it to SPI_execute.)  This is not
  			 * a functional limitation because CREATE TABLE AS is allowed.
  			 */
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("EXECUTE of SELECT ... INTO is not implemented"),
  					 errhint("You might want to use EXECUTE ... INTO or EXECUTE CREATE TABLE ... AS instead.")));
  			break;
  
  			/* Some SPI errors deserve specific error messages */
  		case SPI_ERROR_COPY:
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("cannot COPY to/from client in PL/pgSQL")));
  			break;
  
  		case SPI_ERROR_TRANSACTION:
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("EXECUTE of transaction commands is not implemented")));
  			break;
  
  		default:
  			elog(ERROR, "SPI_execute failed executing query \"%s\": %s",
  				 querystr, SPI_result_code_string(exec_res));
  			break;
  	}
  
  	/* Save result info for GET DIAGNOSTICS */
  	estate->eval_processed = SPI_processed;
  
  	/* Process INTO if present */
  	if (stmt->into)
  	{
  		SPITupleTable *tuptab = SPI_tuptable;
  		uint64		n = SPI_processed;
  		PLpgSQL_variable *target;
  
  		/* If the statement did not return a tuple table, complain */
  		if (tuptab == NULL)
  			ereport(ERROR,
  					(errcode(ERRCODE_SYNTAX_ERROR),
  					 errmsg("INTO used with a command that cannot return data")));
  
  		/* Fetch target's datum entry */
  		target = (PLpgSQL_variable *) estate->datums[stmt->target->dno];
  
  		/*
  		 * If SELECT ... INTO specified STRICT, and the query didn't find
  		 * exactly one row, throw an error.  If STRICT was not specified, then
  		 * allow the query to find any number of rows.
  		 */
  		if (n == 0)
  		{
  			if (stmt->strict)
  			{
  				char	   *errdetail;
  
  				if (estate->func->print_strict_params)
  					errdetail = format_preparedparamsdata(estate, ppd);
  				else
  					errdetail = NULL;
  
  				ereport(ERROR,
  						(errcode(ERRCODE_NO_DATA_FOUND),
  						 errmsg("query returned no rows"),
  						 errdetail ? errdetail_internal("parameters: %s", errdetail) : 0));
  			}
  			/* set the target to NULL(s) */
  			exec_move_row(estate, target, NULL, tuptab->tupdesc);
  		}
  		else
  		{
  			if (n > 1 && stmt->strict)
  			{
  				char	   *errdetail;
  
  				if (estate->func->print_strict_params)
  					errdetail = format_preparedparamsdata(estate, ppd);
  				else
  					errdetail = NULL;
  
  				ereport(ERROR,
  						(errcode(ERRCODE_TOO_MANY_ROWS),
  						 errmsg("query returned more than one row"),
  						 errdetail ? errdetail_internal("parameters: %s", errdetail) : 0));
  			}
  
  			/* Put the first result row into the target */
  			exec_move_row(estate, target, tuptab->vals[0], tuptab->tupdesc);
  		}
  		/* clean up after exec_move_row() */
  		exec_eval_cleanup(estate);
  	}
  	else
  	{
  		/*
  		 * It might be a good idea to raise an error if the query returned
  		 * tuples that are being ignored, but historically we have not done
  		 * that.
  		 */
  	}
  
  	/* Release any result from SPI_execute, as well as transient data */
  	SPI_freetuptable(SPI_tuptable);
  	MemoryContextReset(stmt_mcontext);
  
  	return PLPGSQL_RC_OK;
  }
  
  
  /* ----------
   * exec_stmt_dynfors			Execute a dynamic query, assign each
   *					tuple to a record or row and
   *					execute a group of statements
   *					for it.
   * ----------
   */
  static int
  exec_stmt_dynfors(PLpgSQL_execstate *estate, PLpgSQL_stmt_dynfors *stmt)
  {
  	Portal		portal;
  	int			rc;
  
  	portal = exec_dynquery_with_params(estate, stmt->query, stmt->params,
  									   NULL, 0);
  
  	/*
  	 * Execute the loop
  	 */
  	rc = exec_for_query(estate, (PLpgSQL_stmt_forq *) stmt, portal, true);
  
  	/*
  	 * Close the implicit cursor
  	 */
  	SPI_cursor_close(portal);
  
  	return rc;
  }
  
  
  /* ----------
   * exec_stmt_open			Execute an OPEN cursor statement
   * ----------
   */
  static int
  exec_stmt_open(PLpgSQL_execstate *estate, PLpgSQL_stmt_open *stmt)
  {
  	PLpgSQL_var *curvar;
  	MemoryContext stmt_mcontext = NULL;
  	char	   *curname = NULL;
  	PLpgSQL_expr *query;
  	Portal		portal;
  	ParamListInfo paramLI;
  
  	/* ----------
  	 * Get the cursor variable and if it has an assigned name, check
  	 * that it's not in use currently.
  	 * ----------
  	 */
  	curvar = (PLpgSQL_var *) (estate->datums[stmt->curvar]);
  	if (!curvar->isnull)
  	{
  		MemoryContext oldcontext;
  
  		/* We only need stmt_mcontext to hold the cursor name string */
  		stmt_mcontext = get_stmt_mcontext(estate);
  		oldcontext = MemoryContextSwitchTo(stmt_mcontext);
  		curname = TextDatumGetCString(curvar->value);
  		MemoryContextSwitchTo(oldcontext);
  
  		if (SPI_cursor_find(curname) != NULL)
  			ereport(ERROR,
  					(errcode(ERRCODE_DUPLICATE_CURSOR),
  					 errmsg("cursor \"%s\" already in use", curname)));
  	}
  
  	/* ----------
  	 * Process the OPEN according to it's type.
  	 * ----------
  	 */
  	if (stmt->query != NULL)
  	{
  		/* ----------
  		 * This is an OPEN refcursor FOR SELECT ...
  		 *
  		 * We just make sure the query is planned. The real work is
  		 * done downstairs.
  		 * ----------
  		 */
  		query = stmt->query;
  		if (query->plan == NULL)
  			exec_prepare_plan(estate, query, stmt->cursor_options, true);
  	}
  	else if (stmt->dynquery != NULL)
  	{
  		/* ----------
  		 * This is an OPEN refcursor FOR EXECUTE ...
  		 * ----------
  		 */
  		portal = exec_dynquery_with_params(estate,
  										   stmt->dynquery,
  										   stmt->params,
  										   curname,
  										   stmt->cursor_options);
  
  		/*
  		 * If cursor variable was NULL, store the generated portal name in it.
  		 * Note: exec_dynquery_with_params already reset the stmt_mcontext, so
  		 * curname is a dangling pointer here; but testing it for nullness is
  		 * OK.
  		 */
  		if (curname == NULL)
  			assign_text_var(estate, curvar, portal->name);
  
  		return PLPGSQL_RC_OK;
  	}
  	else
  	{
  		/* ----------
  		 * This is an OPEN cursor
  		 *
  		 * Note: parser should already have checked that statement supplies
  		 * args iff cursor needs them, but we check again to be safe.
  		 * ----------
  		 */
  		if (stmt->argquery != NULL)
  		{
  			/* ----------
  			 * OPEN CURSOR with args.  We fake a SELECT ... INTO ...
  			 * statement to evaluate the args and put 'em into the
  			 * internal row.
  			 * ----------
  			 */
  			PLpgSQL_stmt_execsql set_args;
  
  			if (curvar->cursor_explicit_argrow < 0)
  				ereport(ERROR,
  						(errcode(ERRCODE_SYNTAX_ERROR),
  						 errmsg("arguments given for cursor without arguments")));
  
  			memset(&set_args, 0, sizeof(set_args));
  			set_args.cmd_type = PLPGSQL_STMT_EXECSQL;
  			set_args.lineno = stmt->lineno;
  			set_args.sqlstmt = stmt->argquery;
  			set_args.into = true;
  			/* XXX historically this has not been STRICT */
  			set_args.target = (PLpgSQL_variable *)
  				(estate->datums[curvar->cursor_explicit_argrow]);
  
  			if (exec_stmt_execsql(estate, &set_args) != PLPGSQL_RC_OK)
  				elog(ERROR, "open cursor failed during argument processing");
  		}
  		else
  		{
  			if (curvar->cursor_explicit_argrow >= 0)
  				ereport(ERROR,
  						(errcode(ERRCODE_SYNTAX_ERROR),
  						 errmsg("arguments required for cursor")));
  		}
  
  		query = curvar->cursor_explicit_expr;
  		if (query->plan == NULL)
  			exec_prepare_plan(estate, query, curvar->cursor_options, true);
  	}
  
  	/*
  	 * Set up ParamListInfo for this query
  	 */
  	paramLI = setup_param_list(estate, query);
  
  	/*
  	 * Open the cursor (the paramlist will get copied into the portal)
  	 */
  	portal = SPI_cursor_open_with_paramlist(curname, query->plan,
  											paramLI,
  											estate->readonly_func);
  	if (portal == NULL)
  		elog(ERROR, "could not open cursor: %s",
  			 SPI_result_code_string(SPI_result));
  
  	/*
  	 * If cursor variable was NULL, store the generated portal name in it
  	 */
  	if (curname == NULL)
  		assign_text_var(estate, curvar, portal->name);
  
  	/* If we had any transient data, clean it up */
  	exec_eval_cleanup(estate);
  	if (stmt_mcontext)
  		MemoryContextReset(stmt_mcontext);
  
  	return PLPGSQL_RC_OK;
  }
  
  
  /* ----------
   * exec_stmt_fetch			Fetch from a cursor into a target, or just
   *							move the current position of the cursor
   * ----------
   */
  static int
  exec_stmt_fetch(PLpgSQL_execstate *estate, PLpgSQL_stmt_fetch *stmt)
  {
  	PLpgSQL_var *curvar;
  	long		how_many = stmt->how_many;
  	SPITupleTable *tuptab;
  	Portal		portal;
  	char	   *curname;
  	uint64		n;
  	MemoryContext oldcontext;
  
  	/* ----------
  	 * Get the portal of the cursor by name
  	 * ----------
  	 */
  	curvar = (PLpgSQL_var *) (estate->datums[stmt->curvar]);
  	if (curvar->isnull)
  		ereport(ERROR,
  				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
  				 errmsg("cursor variable \"%s\" is null", curvar->refname)));
  
  	/* Use eval_mcontext for short-lived string */
  	oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate));
  	curname = TextDatumGetCString(curvar->value);
  	MemoryContextSwitchTo(oldcontext);
  
  	portal = SPI_cursor_find(curname);
  	if (portal == NULL)
  		ereport(ERROR,
  				(errcode(ERRCODE_UNDEFINED_CURSOR),
  				 errmsg("cursor \"%s\" does not exist", curname)));
  
  	/* Calculate position for FETCH_RELATIVE or FETCH_ABSOLUTE */
  	if (stmt->expr)
  	{
  		bool		isnull;
  
  		/* XXX should be doing this in LONG not INT width */
  		how_many = exec_eval_integer(estate, stmt->expr, &isnull);
  
  		if (isnull)
  			ereport(ERROR,
  					(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
  					 errmsg("relative or absolute cursor position is null")));
  
  		exec_eval_cleanup(estate);
  	}
  
  	if (!stmt->is_move)
  	{
  		PLpgSQL_variable *target;
  
  		/* ----------
  		 * Fetch 1 tuple from the cursor
  		 * ----------
  		 */
  		SPI_scroll_cursor_fetch(portal, stmt->direction, how_many);
  		tuptab = SPI_tuptable;
  		n = SPI_processed;
  
  		/* ----------
  		 * Set the target appropriately.
  		 * ----------
  		 */
  		target = (PLpgSQL_variable *) estate->datums[stmt->target->dno];
  		if (n == 0)
  			exec_move_row(estate, target, NULL, tuptab->tupdesc);
  		else
  			exec_move_row(estate, target, tuptab->vals[0], tuptab->tupdesc);
  
  		exec_eval_cleanup(estate);
  		SPI_freetuptable(tuptab);
  	}
  	else
  	{
  		/* Move the cursor */
  		SPI_scroll_cursor_move(portal, stmt->direction, how_many);
  		n = SPI_processed;
  	}
  
  	/* Set the ROW_COUNT and the global FOUND variable appropriately. */
  	estate->eval_processed = n;
  	exec_set_found(estate, n != 0);
  
  	return PLPGSQL_RC_OK;
  }
  
  /* ----------
   * exec_stmt_close			Close a cursor
   * ----------
   */
  static int
  exec_stmt_close(PLpgSQL_execstate *estate, PLpgSQL_stmt_close *stmt)
  {
  	PLpgSQL_var *curvar;
  	Portal		portal;
  	char	   *curname;
  	MemoryContext oldcontext;
  
  	/* ----------
  	 * Get the portal of the cursor by name
  	 * ----------
  	 */
  	curvar = (PLpgSQL_var *) (estate->datums[stmt->curvar]);
  	if (curvar->isnull)
  		ereport(ERROR,
  				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
  				 errmsg("cursor variable \"%s\" is null", curvar->refname)));
  
  	/* Use eval_mcontext for short-lived string */
  	oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate));
  	curname = TextDatumGetCString(curvar->value);
  	MemoryContextSwitchTo(oldcontext);
  
  	portal = SPI_cursor_find(curname);
  	if (portal == NULL)
  		ereport(ERROR,
  				(errcode(ERRCODE_UNDEFINED_CURSOR),
  				 errmsg("cursor \"%s\" does not exist", curname)));
  
  	/* ----------
  	 * And close it.
  	 * ----------
  	 */
  	SPI_cursor_close(portal);
  
  	return PLPGSQL_RC_OK;
  }
  
  /*
   * exec_stmt_commit
   *
   * Commit the transaction.
   */
  static int
  exec_stmt_commit(PLpgSQL_execstate *estate, PLpgSQL_stmt_commit *stmt)
  {
  	if (stmt->chain)
  		SPI_commit_and_chain();
  	else
  	{
  		SPI_commit();
  		SPI_start_transaction();
  	}
  
  	estate->simple_eval_estate = NULL;
  	plpgsql_create_econtext(estate);
  
  	return PLPGSQL_RC_OK;
  }
  
  /*
   * exec_stmt_rollback
   *
   * Abort the transaction.
   */
  static int
  exec_stmt_rollback(PLpgSQL_execstate *estate, PLpgSQL_stmt_rollback *stmt)
  {
  	if (stmt->chain)
  		SPI_rollback_and_chain();
  	else
  	{
  		SPI_rollback();
  		SPI_start_transaction();
  	}
  
  	estate->simple_eval_estate = NULL;
  	plpgsql_create_econtext(estate);
  
  	return PLPGSQL_RC_OK;
  }
  
  /*
   * exec_stmt_set
   *
   * Execute SET/RESET statement.
   *
   * We just parse and execute the statement normally, but we have to do it
   * without setting a snapshot, for things like SET TRANSACTION.
   */
  static int
  exec_stmt_set(PLpgSQL_execstate *estate, PLpgSQL_stmt_set *stmt)
  {
  	PLpgSQL_expr *expr = stmt->expr;
  	int			rc;
  
  	if (expr->plan == NULL)
  	{
  		exec_prepare_plan(estate, expr, 0, true);
  		expr->plan->no_snapshots = true;
  	}
  
  	rc = SPI_execute_plan(expr->plan, NULL, NULL, estate->readonly_func, 0);
  
  	if (rc != SPI_OK_UTILITY)
  		elog(ERROR, "SPI_execute_plan failed executing query \"%s\": %s",
  			 expr->query, SPI_result_code_string(rc));
  
  	return PLPGSQL_RC_OK;
  }
  
  /* ----------
   * exec_assign_expr			Put an expression's result into a variable.
   * ----------
   */
  static void
  exec_assign_expr(PLpgSQL_execstate *estate, PLpgSQL_datum *target,
  				 PLpgSQL_expr *expr)
  {
  	Datum		value;
  	bool		isnull;
  	Oid			valtype;
  	int32		valtypmod;
  
  	/*
  	 * If first time through, create a plan for this expression, and then see
  	 * if we can pass the target variable as a read-write parameter to the
  	 * expression.  (This is a bit messy, but it seems cleaner than modifying
  	 * the API of exec_eval_expr for the purpose.)
  	 */
  	if (expr->plan == NULL)
  	{
  		exec_prepare_plan(estate, expr, 0, true);
  		if (target->dtype == PLPGSQL_DTYPE_VAR)
  			exec_check_rw_parameter(expr, target->dno);
  	}
  
  	value = exec_eval_expr(estate, expr, &isnull, &valtype, &valtypmod);
  	exec_assign_value(estate, target, value, isnull, valtype, valtypmod);
  	exec_eval_cleanup(estate);
  }
  
  
  /* ----------
   * exec_assign_c_string		Put a C string into a text variable.
   *
   * We take a NULL pointer as signifying empty string, not SQL null.
   *
   * As with the underlying exec_assign_value, caller is expected to do
   * exec_eval_cleanup later.
   * ----------
   */
  static void
  exec_assign_c_string(PLpgSQL_execstate *estate, PLpgSQL_datum *target,
  					 const char *str)
  {
  	text	   *value;
  	MemoryContext oldcontext;
  
  	/* Use eval_mcontext for short-lived text value */
  	oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate));
  	if (str != NULL)
  		value = cstring_to_text(str);
  	else
  		value = cstring_to_text("");
  	MemoryContextSwitchTo(oldcontext);
  
  	exec_assign_value(estate, target, PointerGetDatum(value), false,
  					  TEXTOID, -1);
  }
  
  
  /* ----------
   * exec_assign_value			Put a value into a target datum
   *
   * Note: in some code paths, this will leak memory in the eval_mcontext;
   * we assume that will be cleaned up later by exec_eval_cleanup.  We cannot
   * call exec_eval_cleanup here for fear of destroying the input Datum value.
   * ----------
   */
  static void
  exec_assign_value(PLpgSQL_execstate *estate,
  				  PLpgSQL_datum *target,
  				  Datum value, bool isNull,
  				  Oid valtype, int32 valtypmod)
  {
  	switch (target->dtype)
  	{
  		case PLPGSQL_DTYPE_VAR:
  		case PLPGSQL_DTYPE_PROMISE:
  			{
  				/*
  				 * Target is a variable
  				 */
  				PLpgSQL_var *var = (PLpgSQL_var *) target;
  				Datum		newvalue;
  
  				newvalue = exec_cast_value(estate,
  										   value,
  										   &isNull,
  										   valtype,
  										   valtypmod,
  										   var->datatype->typoid,
  										   var->datatype->atttypmod);
  
  				if (isNull && var->notnull)
  					ereport(ERROR,
  							(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
  							 errmsg("null value cannot be assigned to variable \"%s\" declared NOT NULL",
  									var->refname)));
  
  				/*
  				 * If type is by-reference, copy the new value (which is
  				 * probably in the eval_mcontext) into the procedure's main
  				 * memory context.  But if it's a read/write reference to an
  				 * expanded object, no physical copy needs to happen; at most
  				 * we need to reparent the object's memory context.
  				 *
  				 * If it's an array, we force the value to be stored in R/W
  				 * expanded form.  This wins if the function later does, say,
  				 * a lot of array subscripting operations on the variable, and
  				 * otherwise might lose.  We might need to use a different
  				 * heuristic, but it's too soon to tell.  Also, are there
  				 * cases where it'd be useful to force non-array values into
  				 * expanded form?
  				 */
  				if (!var->datatype->typbyval && !isNull)
  				{
  					if (var->datatype->typisarray &&
  						!VARATT_IS_EXTERNAL_EXPANDED_RW(DatumGetPointer(newvalue)))
  					{
  						/* array and not already R/W, so apply expand_array */
  						newvalue = expand_array(newvalue,
  												estate->datum_context,
  												NULL);
  					}
  					else
  					{
  						/* else transfer value if R/W, else just datumCopy */
  						newvalue = datumTransfer(newvalue,
  												 false,
  												 var->datatype->typlen);
  					}
  				}
  
  				/*
  				 * Now free the old value, if any, and assign the new one. But
  				 * skip the assignment if old and new values are the same.
  				 * Note that for expanded objects, this test is necessary and
  				 * cannot reliably be made any earlier; we have to be looking
  				 * at the object's standard R/W pointer to be sure pointer
  				 * equality is meaningful.
  				 *
  				 * Also, if it's a promise variable, we should disarm the
  				 * promise in any case --- otherwise, assigning null to an
  				 * armed promise variable would fail to disarm the promise.
  				 */
  				if (var->value != newvalue || var->isnull || isNull)
  					assign_simple_var(estate, var, newvalue, isNull,
  									  (!var->datatype->typbyval && !isNull));
  				else
  					var->promise = PLPGSQL_PROMISE_NONE;
  				break;
  			}
  
  		case PLPGSQL_DTYPE_ROW:
  			{
  				/*
  				 * Target is a row variable
  				 */
  				PLpgSQL_row *row = (PLpgSQL_row *) target;
  
  				if (isNull)
  				{
  					/* If source is null, just assign nulls to the row */
  					exec_move_row(estate, (PLpgSQL_variable *) row,
  								  NULL, NULL);
  				}
  				else
  				{
  					/* Source must be of RECORD or composite type */
  					if (!type_is_rowtype(valtype))
  						ereport(ERROR,
  								(errcode(ERRCODE_DATATYPE_MISMATCH),
  								 errmsg("cannot assign non-composite value to a row variable")));
  					exec_move_row_from_datum(estate, (PLpgSQL_variable *) row,
  											 value);
  				}
  				break;
  			}
  
  		case PLPGSQL_DTYPE_REC:
  			{
  				/*
  				 * Target is a record variable
  				 */
  				PLpgSQL_rec *rec = (PLpgSQL_rec *) target;
  
  				if (isNull)
  				{
  					if (rec->notnull)
  						ereport(ERROR,
  								(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
  								 errmsg("null value cannot be assigned to variable \"%s\" declared NOT NULL",
  										rec->refname)));
  
  					/* Set variable to a simple NULL */
  					exec_move_row(estate, (PLpgSQL_variable *) rec,
  								  NULL, NULL);
  				}
  				else
  				{
  					/* Source must be of RECORD or composite type */
  					if (!type_is_rowtype(valtype))
  						ereport(ERROR,
  								(errcode(ERRCODE_DATATYPE_MISMATCH),
  								 errmsg("cannot assign non-composite value to a record variable")));
  					exec_move_row_from_datum(estate, (PLpgSQL_variable *) rec,
  											 value);
  				}
  				break;
  			}
  
  		case PLPGSQL_DTYPE_RECFIELD:
  			{
  				/*
  				 * Target is a field of a record
  				 */
  				PLpgSQL_recfield *recfield = (PLpgSQL_recfield *) target;
  				PLpgSQL_rec *rec;
  				ExpandedRecordHeader *erh;
  
  				rec = (PLpgSQL_rec *) (estate->datums[recfield->recparentno]);
  				erh = rec->erh;
  
  				/*
  				 * If record variable is NULL, instantiate it if it has a
  				 * named composite type, else complain.  (This won't change
  				 * the logical state of the record, but if we successfully
  				 * assign below, the unassigned fields will all become NULLs.)
  				 */
  				if (erh == NULL)
  				{
  					instantiate_empty_record_variable(estate, rec);
  					erh = rec->erh;
  				}
  
  				/*
  				 * Look up the field's properties if we have not already, or
  				 * if the tuple descriptor ID changed since last time.
  				 */
  				if (unlikely(recfield->rectupledescid != erh->er_tupdesc_id))
  				{
  					if (!expanded_record_lookup_field(erh,
  													  recfield->fieldname,
  													  &recfield->finfo))
  						ereport(ERROR,
  								(errcode(ERRCODE_UNDEFINED_COLUMN),
  								 errmsg("record \"%s\" has no field \"%s\"",
  										rec->refname, recfield->fieldname)));
  					recfield->rectupledescid = erh->er_tupdesc_id;
  				}
  
  				/* We don't support assignments to system columns. */
  				if (recfield->finfo.fnumber <= 0)
  					ereport(ERROR,
  							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  							 errmsg("cannot assign to system column \"%s\"",
  									recfield->fieldname)));
  
  				/* Cast the new value to the right type, if needed. */
  				value = exec_cast_value(estate,
  										value,
  										&isNull,
  										valtype,
  										valtypmod,
  										recfield->finfo.ftypeid,
  										recfield->finfo.ftypmod);
  
  				/* And assign it. */
  				expanded_record_set_field(erh, recfield->finfo.fnumber,
  										  value, isNull, !estate->atomic);
  				break;
  			}
  
  		case PLPGSQL_DTYPE_ARRAYELEM:
  			{
  				/*
  				 * Target is an element of an array
  				 */
  				PLpgSQL_arrayelem *arrayelem;
  				int			nsubscripts;
  				int			i;
  				PLpgSQL_expr *subscripts[MAXDIM];
  				int			subscriptvals[MAXDIM];
  				Datum		oldarraydatum,
  							newarraydatum,
  							coerced_value;
  				bool		oldarrayisnull;
  				Oid			parenttypoid;
  				int32		parenttypmod;
  				SPITupleTable *save_eval_tuptable;
  				MemoryContext oldcontext;
  
  				/*
  				 * We need to do subscript evaluation, which might require
  				 * evaluating general expressions; and the caller might have
  				 * done that too in order to prepare the input Datum.  We have
  				 * to save and restore the caller's SPI_execute result, if
  				 * any.
  				 */
  				save_eval_tuptable = estate->eval_tuptable;
  				estate->eval_tuptable = NULL;
  
  				/*
  				 * To handle constructs like x[1][2] := something, we have to
  				 * be prepared to deal with a chain of arrayelem datums. Chase
  				 * back to find the base array datum, and save the subscript
  				 * expressions as we go.  (We are scanning right to left here,
  				 * but want to evaluate the subscripts left-to-right to
  				 * minimize surprises.)  Note that arrayelem is left pointing
  				 * to the leftmost arrayelem datum, where we will cache the
  				 * array element type data.
  				 */
  				nsubscripts = 0;
  				do
  				{
  					arrayelem = (PLpgSQL_arrayelem *) target;
  					if (nsubscripts >= MAXDIM)
  						ereport(ERROR,
  								(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
  								 errmsg("number of array dimensions (%d) exceeds the maximum allowed (%d)",
  										nsubscripts + 1, MAXDIM)));
  					subscripts[nsubscripts++] = arrayelem->subscript;
  					target = estate->datums[arrayelem->arrayparentno];
  				} while (target->dtype == PLPGSQL_DTYPE_ARRAYELEM);
  
  				/* Fetch current value of array datum */
  				exec_eval_datum(estate, target,
  								&parenttypoid, &parenttypmod,
  								&oldarraydatum, &oldarrayisnull);
  
  				/* Update cached type data if necessary */
  				if (arrayelem->parenttypoid != parenttypoid ||
  					arrayelem->parenttypmod != parenttypmod)
  				{
  					Oid			arraytypoid;
  					int32		arraytypmod = parenttypmod;
  					int16		arraytyplen;
  					Oid			elemtypoid;
  					int16		elemtyplen;
  					bool		elemtypbyval;
  					char		elemtypalign;
  
  					/* If target is domain over array, reduce to base type */
  					arraytypoid = getBaseTypeAndTypmod(parenttypoid,
  													   &arraytypmod);
  
  					/* ... and identify the element type */
  					elemtypoid = get_element_type(arraytypoid);
  					if (!OidIsValid(elemtypoid))
  						ereport(ERROR,
  								(errcode(ERRCODE_DATATYPE_MISMATCH),
  								 errmsg("subscripted object is not an array")));
  
  					/* Collect needed data about the types */
  					arraytyplen = get_typlen(arraytypoid);
  
  					get_typlenbyvalalign(elemtypoid,
  										 &elemtyplen,
  										 &elemtypbyval,
  										 &elemtypalign);
  
  					/* Now safe to update the cached data */
  					arrayelem->parenttypoid = parenttypoid;
  					arrayelem->parenttypmod = parenttypmod;
  					arrayelem->arraytypoid = arraytypoid;
  					arrayelem->arraytypmod = arraytypmod;
  					arrayelem->arraytyplen = arraytyplen;
  					arrayelem->elemtypoid = elemtypoid;
  					arrayelem->elemtyplen = elemtyplen;
  					arrayelem->elemtypbyval = elemtypbyval;
  					arrayelem->elemtypalign = elemtypalign;
  				}
  
  				/*
  				 * Evaluate the subscripts, switch into left-to-right order.
  				 * Like the expression built by ExecInitSubscriptingRef(),
  				 * complain if any subscript is null.
  				 */
  				for (i = 0; i < nsubscripts; i++)
  				{
  					bool		subisnull;
  
  					subscriptvals[i] =
  						exec_eval_integer(estate,
  										  subscripts[nsubscripts - 1 - i],
  										  &subisnull);
  					if (subisnull)
  						ereport(ERROR,
  								(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
  								 errmsg("array subscript in assignment must not be null")));
  
  					/*
  					 * Clean up in case the subscript expression wasn't
  					 * simple. We can't do exec_eval_cleanup, but we can do
  					 * this much (which is safe because the integer subscript
  					 * value is surely pass-by-value), and we must do it in
  					 * case the next subscript expression isn't simple either.
  					 */
  					if (estate->eval_tuptable != NULL)
  						SPI_freetuptable(estate->eval_tuptable);
  					estate->eval_tuptable = NULL;
  				}
  
  				/* Now we can restore caller's SPI_execute result if any. */
  				Assert(estate->eval_tuptable == NULL);
  				estate->eval_tuptable = save_eval_tuptable;
  
  				/* Coerce source value to match array element type. */
  				coerced_value = exec_cast_value(estate,
  												value,
  												&isNull,
  												valtype,
  												valtypmod,
  												arrayelem->elemtypoid,
  												arrayelem->arraytypmod);
  
  				/*
  				 * If the original array is null, cons up an empty array so
  				 * that the assignment can proceed; we'll end with a
  				 * one-element array containing just the assigned-to
  				 * subscript.  This only works for varlena arrays, though; for
  				 * fixed-length array types we skip the assignment.  We can't
  				 * support assignment of a null entry into a fixed-length
  				 * array, either, so that's a no-op too.  This is all ugly but
  				 * corresponds to the current behavior of execExpr*.c.
  				 */
  				if (arrayelem->arraytyplen > 0 &&	/* fixed-length array? */
  					(oldarrayisnull || isNull))
  					return;
  
  				/* empty array, if any, and newarraydatum are short-lived */
  				oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate));
  
  				if (oldarrayisnull)
  					oldarraydatum = PointerGetDatum(construct_empty_array(arrayelem->elemtypoid));
  
  				/*
  				 * Build the modified array value.
  				 */
  				newarraydatum = array_set_element(oldarraydatum,
  												  nsubscripts,
  												  subscriptvals,
  												  coerced_value,
  												  isNull,
  												  arrayelem->arraytyplen,
  												  arrayelem->elemtyplen,
  												  arrayelem->elemtypbyval,
  												  arrayelem->elemtypalign);
  
  				MemoryContextSwitchTo(oldcontext);
  
  				/*
  				 * Assign the new array to the base variable.  It's never NULL
  				 * at this point.  Note that if the target is a domain,
  				 * coercing the base array type back up to the domain will
  				 * happen within exec_assign_value.
  				 */
  				exec_assign_value(estate, target,
  								  newarraydatum,
  								  false,
  								  arrayelem->arraytypoid,
  								  arrayelem->arraytypmod);
  				break;
  			}
  
  		default:
  			elog(ERROR, "unrecognized dtype: %d", target->dtype);
  	}
  }
  
  /*
   * exec_eval_datum				Get current value of a PLpgSQL_datum
   *
   * The type oid, typmod, value in Datum format, and null flag are returned.
   *
   * At present this doesn't handle PLpgSQL_expr or PLpgSQL_arrayelem datums;
   * that's not needed because we never pass references to such datums to SPI.
   *
   * NOTE: the returned Datum points right at the stored value in the case of
   * pass-by-reference datatypes.  Generally callers should take care not to
   * modify the stored value.  Some callers intentionally manipulate variables
   * referenced by R/W expanded pointers, though; it is those callers'
   * responsibility that the results are semantically OK.
   *
   * In some cases we have to palloc a return value, and in such cases we put
   * it into the estate's eval_mcontext.
   */
  static void
  exec_eval_datum(PLpgSQL_execstate *estate,
  				PLpgSQL_datum *datum,
  				Oid *typeid,
  				int32 *typetypmod,
  				Datum *value,
  				bool *isnull)
  {
  	MemoryContext oldcontext;
  
  	switch (datum->dtype)
  	{
  		case PLPGSQL_DTYPE_PROMISE:
  			/* fulfill promise if needed, then handle like regular var */
  			plpgsql_fulfill_promise(estate, (PLpgSQL_var *) datum);
  
  			/* FALL THRU */
  
  		case PLPGSQL_DTYPE_VAR:
  			{
  				PLpgSQL_var *var = (PLpgSQL_var *) datum;
  
  				*typeid = var->datatype->typoid;
  				*typetypmod = var->datatype->atttypmod;
  				*value = var->value;
  				*isnull = var->isnull;
  				break;
  			}
  
  		case PLPGSQL_DTYPE_ROW:
  			{
  				PLpgSQL_row *row = (PLpgSQL_row *) datum;
  				HeapTuple	tup;
  
  				/* We get here if there are multiple OUT parameters */
  				if (!row->rowtupdesc)	/* should not happen */
  					elog(ERROR, "row variable has no tupdesc");
  				/* Make sure we have a valid type/typmod setting */
  				BlessTupleDesc(row->rowtupdesc);
  				oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate));
  				tup = make_tuple_from_row(estate, row, row->rowtupdesc);
  				if (tup == NULL)	/* should not happen */
  					elog(ERROR, "row not compatible with its own tupdesc");
  				*typeid = row->rowtupdesc->tdtypeid;
  				*typetypmod = row->rowtupdesc->tdtypmod;
  				*value = HeapTupleGetDatum(tup);
  				*isnull = false;
  				MemoryContextSwitchTo(oldcontext);
  				break;
  			}
  
  		case PLPGSQL_DTYPE_REC:
  			{
  				PLpgSQL_rec *rec = (PLpgSQL_rec *) datum;
  
  				if (rec->erh == NULL)
  				{
  					/* Treat uninstantiated record as a simple NULL */
  					*value = (Datum) 0;
  					*isnull = true;
  					/* Report variable's declared type */
  					*typeid = rec->rectypeid;
  					*typetypmod = -1;
  				}
  				else
  				{
  					if (ExpandedRecordIsEmpty(rec->erh))
  					{
  						/* Empty record is also a NULL */
  						*value = (Datum) 0;
  						*isnull = true;
  					}
  					else
  					{
  						*value = ExpandedRecordGetDatum(rec->erh);
  						*isnull = false;
  					}
  					if (rec->rectypeid != RECORDOID)
  					{
  						/* Report variable's declared type, if not RECORD */
  						*typeid = rec->rectypeid;
  						*typetypmod = -1;
  					}
  					else
  					{
  						/* Report record's actual type if declared RECORD */
  						*typeid = rec->erh->er_typeid;
  						*typetypmod = rec->erh->er_typmod;
  					}
  				}
  				break;
  			}
  
  		case PLPGSQL_DTYPE_RECFIELD:
  			{
  				PLpgSQL_recfield *recfield = (PLpgSQL_recfield *) datum;
  				PLpgSQL_rec *rec;
  				ExpandedRecordHeader *erh;
  
  				rec = (PLpgSQL_rec *) (estate->datums[recfield->recparentno]);
  				erh = rec->erh;
  
  				/*
  				 * If record variable is NULL, instantiate it if it has a
  				 * named composite type, else complain.  (This won't change
  				 * the logical state of the record: it's still NULL.)
  				 */
  				if (erh == NULL)
  				{
  					instantiate_empty_record_variable(estate, rec);
  					erh = rec->erh;
  				}
  
  				/*
  				 * Look up the field's properties if we have not already, or
  				 * if the tuple descriptor ID changed since last time.
  				 */
  				if (unlikely(recfield->rectupledescid != erh->er_tupdesc_id))
  				{
  					if (!expanded_record_lookup_field(erh,
  													  recfield->fieldname,
  													  &recfield->finfo))
  						ereport(ERROR,
  								(errcode(ERRCODE_UNDEFINED_COLUMN),
  								 errmsg("record \"%s\" has no field \"%s\"",
  										rec->refname, recfield->fieldname)));
  					recfield->rectupledescid = erh->er_tupdesc_id;
  				}
  
  				/* Report type data. */
  				*typeid = recfield->finfo.ftypeid;
  				*typetypmod = recfield->finfo.ftypmod;
  
  				/* And fetch the field value. */
  				*value = expanded_record_get_field(erh,
  												   recfield->finfo.fnumber,
  												   isnull);
  				break;
  			}
  
  		default:
  			elog(ERROR, "unrecognized dtype: %d", datum->dtype);
  	}
  }
  
  /*
   * plpgsql_exec_get_datum_type				Get datatype of a PLpgSQL_datum
   *
   * This is the same logic as in exec_eval_datum, but we skip acquiring
   * the actual value of the variable.  Also, needn't support DTYPE_ROW.
   */
  Oid
  plpgsql_exec_get_datum_type(PLpgSQL_execstate *estate,
  							PLpgSQL_datum *datum)
  {
  	Oid			typeid;
  
  	switch (datum->dtype)
  	{
  		case PLPGSQL_DTYPE_VAR:
  		case PLPGSQL_DTYPE_PROMISE:
  			{
  				PLpgSQL_var *var = (PLpgSQL_var *) datum;
  
  				typeid = var->datatype->typoid;
  				break;
  			}
  
  		case PLPGSQL_DTYPE_REC:
  			{
  				PLpgSQL_rec *rec = (PLpgSQL_rec *) datum;
  
  				if (rec->erh == NULL || rec->rectypeid != RECORDOID)
  				{
  					/* Report variable's declared type */
  					typeid = rec->rectypeid;
  				}
  				else
  				{
  					/* Report record's actual type if declared RECORD */
  					typeid = rec->erh->er_typeid;
  				}
  				break;
  			}
  
  		case PLPGSQL_DTYPE_RECFIELD:
  			{
  				PLpgSQL_recfield *recfield = (PLpgSQL_recfield *) datum;
  				PLpgSQL_rec *rec;
  
  				rec = (PLpgSQL_rec *) (estate->datums[recfield->recparentno]);
  
  				/*
  				 * If record variable is NULL, instantiate it if it has a
  				 * named composite type, else complain.  (This won't change
  				 * the logical state of the record: it's still NULL.)
  				 */
  				if (rec->erh == NULL)
  					instantiate_empty_record_variable(estate, rec);
  
  				/*
  				 * Look up the field's properties if we have not already, or
  				 * if the tuple descriptor ID changed since last time.
  				 */
  				if (unlikely(recfield->rectupledescid != rec->erh->er_tupdesc_id))
  				{
  					if (!expanded_record_lookup_field(rec->erh,
  													  recfield->fieldname,
  													  &recfield->finfo))
  						ereport(ERROR,
  								(errcode(ERRCODE_UNDEFINED_COLUMN),
  								 errmsg("record \"%s\" has no field \"%s\"",
  										rec->refname, recfield->fieldname)));
  					recfield->rectupledescid = rec->erh->er_tupdesc_id;
  				}
  
  				typeid = recfield->finfo.ftypeid;
  				break;
  			}
  
  		default:
  			elog(ERROR, "unrecognized dtype: %d", datum->dtype);
  			typeid = InvalidOid;	/* keep compiler quiet */
  			break;
  	}
  
  	return typeid;
  }
  
  /*
   * plpgsql_exec_get_datum_type_info			Get datatype etc of a PLpgSQL_datum
   *
   * An extended version of plpgsql_exec_get_datum_type, which also retrieves the
   * typmod and collation of the datum.  Note however that we don't report the
   * possibly-mutable typmod of RECORD values, but say -1 always.
   */
  void
  plpgsql_exec_get_datum_type_info(PLpgSQL_execstate *estate,
  								 PLpgSQL_datum *datum,
  								 Oid *typeId, int32 *typMod, Oid *collation)
  {
  	switch (datum->dtype)
  	{
  		case PLPGSQL_DTYPE_VAR:
  		case PLPGSQL_DTYPE_PROMISE:
  			{
  				PLpgSQL_var *var = (PLpgSQL_var *) datum;
  
  				*typeId = var->datatype->typoid;
  				*typMod = var->datatype->atttypmod;
  				*collation = var->datatype->collation;
  				break;
  			}
  
  		case PLPGSQL_DTYPE_REC:
  			{
  				PLpgSQL_rec *rec = (PLpgSQL_rec *) datum;
  
  				if (rec->erh == NULL || rec->rectypeid != RECORDOID)
  				{
  					/* Report variable's declared type */
  					*typeId = rec->rectypeid;
  					*typMod = -1;
  				}
  				else
  				{
  					/* Report record's actual type if declared RECORD */
  					*typeId = rec->erh->er_typeid;
  					/* do NOT return the mutable typmod of a RECORD variable */
  					*typMod = -1;
  				}
  				/* composite types are never collatable */
  				*collation = InvalidOid;
  				break;
  			}
  
  		case PLPGSQL_DTYPE_RECFIELD:
  			{
  				PLpgSQL_recfield *recfield = (PLpgSQL_recfield *) datum;
  				PLpgSQL_rec *rec;
  
  				rec = (PLpgSQL_rec *) (estate->datums[recfield->recparentno]);
  
  				/*
  				 * If record variable is NULL, instantiate it if it has a
  				 * named composite type, else complain.  (This won't change
  				 * the logical state of the record: it's still NULL.)
  				 */
  				if (rec->erh == NULL)
  					instantiate_empty_record_variable(estate, rec);
  
  				/*
  				 * Look up the field's properties if we have not already, or
  				 * if the tuple descriptor ID changed since last time.
  				 */
  				if (unlikely(recfield->rectupledescid != rec->erh->er_tupdesc_id))
  				{
  					if (!expanded_record_lookup_field(rec->erh,
  													  recfield->fieldname,
  													  &recfield->finfo))
  						ereport(ERROR,
  								(errcode(ERRCODE_UNDEFINED_COLUMN),
  								 errmsg("record \"%s\" has no field \"%s\"",
  										rec->refname, recfield->fieldname)));
  					recfield->rectupledescid = rec->erh->er_tupdesc_id;
  				}
  
  				*typeId = recfield->finfo.ftypeid;
  				*typMod = recfield->finfo.ftypmod;
  				*collation = recfield->finfo.fcollation;
  				break;
  			}
  
  		default:
  			elog(ERROR, "unrecognized dtype: %d", datum->dtype);
  			*typeId = InvalidOid;	/* keep compiler quiet */
  			*typMod = -1;
  			*collation = InvalidOid;
  			break;
  	}
  }
  
  /* ----------
   * exec_eval_integer		Evaluate an expression, coerce result to int4
   *
   * Note we do not do exec_eval_cleanup here; the caller must do it at
   * some later point.  (We do this because the caller may be holding the
   * results of other, pass-by-reference, expression evaluations, such as
   * an array value to be subscripted.)
   * ----------
   */
  static int
  exec_eval_integer(PLpgSQL_execstate *estate,
  				  PLpgSQL_expr *expr,
  				  bool *isNull)
  {
  	Datum		exprdatum;
  	Oid			exprtypeid;
  	int32		exprtypmod;
  
  	exprdatum = exec_eval_expr(estate, expr, isNull, &exprtypeid, &exprtypmod);
  	exprdatum = exec_cast_value(estate, exprdatum, isNull,
  								exprtypeid, exprtypmod,
  								INT4OID, -1);
  	return DatumGetInt32(exprdatum);
  }
  
  /* ----------
   * exec_eval_boolean		Evaluate an expression, coerce result to bool
   *
   * Note we do not do exec_eval_cleanup here; the caller must do it at
   * some later point.
   * ----------
   */
  static bool
  exec_eval_boolean(PLpgSQL_execstate *estate,
  				  PLpgSQL_expr *expr,
  				  bool *isNull)
  {
  	Datum		exprdatum;
  	Oid			exprtypeid;
  	int32		exprtypmod;
  
  	exprdatum = exec_eval_expr(estate, expr, isNull, &exprtypeid, &exprtypmod);
  	exprdatum = exec_cast_value(estate, exprdatum, isNull,
  								exprtypeid, exprtypmod,
  								BOOLOID, -1);
  	return DatumGetBool(exprdatum);
  }
  
  /* ----------
   * exec_eval_expr			Evaluate an expression and return
   *					the result Datum, along with data type/typmod.
   *
   * NOTE: caller must do exec_eval_cleanup when done with the Datum.
   * ----------
   */
  static Datum
  exec_eval_expr(PLpgSQL_execstate *estate,
  			   PLpgSQL_expr *expr,
  			   bool *isNull,
  			   Oid *rettype,
  			   int32 *rettypmod)
  {
  	Datum		result = 0;
  	int			rc;
  	Form_pg_attribute attr;
  
  	/*
  	 * If first time through, create a plan for this expression.
  	 */
  	if (expr->plan == NULL)
  		exec_prepare_plan(estate, expr, CURSOR_OPT_PARALLEL_OK, true);
  
  	/*
  	 * If this is a simple expression, bypass SPI and use the executor
  	 * directly
  	 */
  	if (exec_eval_simple_expr(estate, expr,
  							  &result, isNull, rettype, rettypmod))
  		return result;
  
  	/*
  	 * Else do it the hard way via exec_run_select
  	 */
  	rc = exec_run_select(estate, expr, 2, NULL);
  	if (rc != SPI_OK_SELECT)
  		ereport(ERROR,
  				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  				 errmsg("query \"%s\" did not return data", expr->query)));
  
  	/*
  	 * Check that the expression returns exactly one column...
  	 */
  	if (estate->eval_tuptable->tupdesc->natts != 1)
  		ereport(ERROR,
  				(errcode(ERRCODE_SYNTAX_ERROR),
  				 errmsg_plural("query \"%s\" returned %d column",
  							   "query \"%s\" returned %d columns",
  							   estate->eval_tuptable->tupdesc->natts,
  							   expr->query,
  							   estate->eval_tuptable->tupdesc->natts)));
  
  	/*
  	 * ... and get the column's datatype.
  	 */
  	attr = TupleDescAttr(estate->eval_tuptable->tupdesc, 0);
  	*rettype = attr->atttypid;
  	*rettypmod = attr->atttypmod;
  
  	/*
  	 * If there are no rows selected, the result is a NULL of that type.
  	 */
  	if (estate->eval_processed == 0)
  	{
  		*isNull = true;
  		return (Datum) 0;
  	}
  
  	/*
  	 * Check that the expression returned no more than one row.
  	 */
  	if (estate->eval_processed != 1)
  		ereport(ERROR,
  				(errcode(ERRCODE_CARDINALITY_VIOLATION),
  				 errmsg("query \"%s\" returned more than one row",
  						expr->query)));
  
  	/*
  	 * Return the single result Datum.
  	 */
  	return SPI_getbinval(estate->eval_tuptable->vals[0],
  						 estate->eval_tuptable->tupdesc, 1, isNull);
  }
  
  
  /* ----------
   * exec_run_select			Execute a select query
   * ----------
   */
  static int
  exec_run_select(PLpgSQL_execstate *estate,
  				PLpgSQL_expr *expr, long maxtuples, Portal *portalP)
  {
  	ParamListInfo paramLI;
  	int			rc;
  
  	/*
  	 * On the first call for this expression generate the plan.
  	 *
  	 * If we don't need to return a portal, then we're just going to execute
  	 * the query once, which means it's OK to use a parallel plan, even if the
  	 * number of rows being fetched is limited.  If we do need to return a
  	 * portal, the caller might do cursor operations, which parallel query
  	 * can't support.
  	 */
  	if (expr->plan == NULL)
  		exec_prepare_plan(estate, expr,
  						  portalP == NULL ? CURSOR_OPT_PARALLEL_OK : 0, true);
  
  	/*
  	 * Set up ParamListInfo to pass to executor
  	 */
  	paramLI = setup_param_list(estate, expr);
  
  	/*
  	 * If a portal was requested, put the query and paramlist into the portal
  	 */
  	if (portalP != NULL)
  	{
  		*portalP = SPI_cursor_open_with_paramlist(NULL, expr->plan,
  												  paramLI,
  												  estate->readonly_func);
  		if (*portalP == NULL)
  			elog(ERROR, "could not open implicit cursor for query \"%s\": %s",
  				 expr->query, SPI_result_code_string(SPI_result));
  		exec_eval_cleanup(estate);
  		return SPI_OK_CURSOR;
  	}
  
  	/*
  	 * Execute the query
  	 */
  	rc = SPI_execute_plan_with_paramlist(expr->plan, paramLI,
  										 estate->readonly_func, maxtuples);
  	if (rc != SPI_OK_SELECT)
  		ereport(ERROR,
  				(errcode(ERRCODE_SYNTAX_ERROR),
  				 errmsg("query \"%s\" is not a SELECT", expr->query)));
  
  	/* Save query results for eventual cleanup */
  	Assert(estate->eval_tuptable == NULL);
  	estate->eval_tuptable = SPI_tuptable;
  	estate->eval_processed = SPI_processed;
  
  	return rc;
  }
  
  
  /*
   * exec_for_query --- execute body of FOR loop for each row from a portal
   *
   * Used by exec_stmt_fors, exec_stmt_forc and exec_stmt_dynfors
   */
  static int
  exec_for_query(PLpgSQL_execstate *estate, PLpgSQL_stmt_forq *stmt,
  			   Portal portal, bool prefetch_ok)
  {
  	PLpgSQL_variable *var;
  	SPITupleTable *tuptab;
  	bool		found = false;
  	int			rc = PLPGSQL_RC_OK;
  	uint64		previous_id = INVALID_TUPLEDESC_IDENTIFIER;
  	bool		tupdescs_match = true;
  	uint64		n;
  
  	/* Fetch loop variable's datum entry */
  	var = (PLpgSQL_variable *) estate->datums[stmt->var->dno];
  
  	/*
  	 * Make sure the portal doesn't get closed by the user statements we
  	 * execute.
  	 */
  	PinPortal(portal);
  
  	/*
  	 * Fetch the initial tuple(s).  If prefetching is allowed then we grab a
  	 * few more rows to avoid multiple trips through executor startup
  	 * overhead.
  	 */
  	SPI_cursor_fetch(portal, true, prefetch_ok ? 10 : 1);
  	tuptab = SPI_tuptable;
  	n = SPI_processed;
  
  	/*
  	 * If the query didn't return any rows, set the target to NULL and fall
  	 * through with found = false.
  	 */
  	if (n == 0)
  	{
  		exec_move_row(estate, var, NULL, tuptab->tupdesc);
  		exec_eval_cleanup(estate);
  	}
  	else
  		found = true;			/* processed at least one tuple */
  
  	/*
  	 * Now do the loop
  	 */
  	while (n > 0)
  	{
  		uint64		i;
  
  		for (i = 0; i < n; i++)
  		{
  			/*
  			 * Assign the tuple to the target.  Here, because we know that all
  			 * loop iterations should be assigning the same tupdesc, we can
  			 * optimize away repeated creations of expanded records with
  			 * identical tupdescs.  Testing for changes of er_tupdesc_id is
  			 * reliable even if the loop body contains assignments that
  			 * replace the target's value entirely, because it's assigned from
  			 * a process-global counter.  The case where the tupdescs don't
  			 * match could possibly be handled more efficiently than this
  			 * coding does, but it's not clear extra effort is worthwhile.
  			 */
  			if (var->dtype == PLPGSQL_DTYPE_REC)
  			{
  				PLpgSQL_rec *rec = (PLpgSQL_rec *) var;
  
  				if (rec->erh &&
  					rec->erh->er_tupdesc_id == previous_id &&
  					tupdescs_match)
  				{
  					/* Only need to assign a new tuple value */
  					expanded_record_set_tuple(rec->erh, tuptab->vals[i],
  											  true, !estate->atomic);
  				}
  				else
  				{
  					/*
  					 * First time through, or var's tupdesc changed in loop,
  					 * or we have to do it the hard way because type coercion
  					 * is needed.
  					 */
  					exec_move_row(estate, var,
  								  tuptab->vals[i], tuptab->tupdesc);
  
  					/*
  					 * Check to see if physical assignment is OK next time.
  					 * Once the tupdesc comparison has failed once, we don't
  					 * bother rechecking in subsequent loop iterations.
  					 */
  					if (tupdescs_match)
  					{
  						tupdescs_match =
  							(rec->rectypeid == RECORDOID ||
  							 rec->rectypeid == tuptab->tupdesc->tdtypeid ||
  							 compatible_tupdescs(tuptab->tupdesc,
  												 expanded_record_get_tupdesc(rec->erh)));
  					}
  					previous_id = rec->erh->er_tupdesc_id;
  				}
  			}
  			else
  				exec_move_row(estate, var, tuptab->vals[i], tuptab->tupdesc);
  
  			exec_eval_cleanup(estate);
  
  			/*
  			 * Execute the statements
  			 */
  			rc = exec_stmts(estate, stmt->body);
  
  			LOOP_RC_PROCESSING(stmt->label, goto loop_exit);
  		}
  
  		SPI_freetuptable(tuptab);
  
  		/*
  		 * Fetch more tuples.  If prefetching is allowed, grab 50 at a time.
  		 */
  		SPI_cursor_fetch(portal, true, prefetch_ok ? 50 : 1);
  		tuptab = SPI_tuptable;
  		n = SPI_processed;
  	}
  
  loop_exit:
  
  	/*
  	 * Release last group of tuples (if any)
  	 */
  	SPI_freetuptable(tuptab);
  
  	UnpinPortal(portal);
  
  	/*
  	 * Set the FOUND variable to indicate the result of executing the loop
  	 * (namely, whether we looped one or more times). This must be set last so
  	 * that it does not interfere with the value of the FOUND variable inside
  	 * the loop processing itself.
  	 */
  	exec_set_found(estate, found);
  
  	return rc;
  }
  
  
  /* ----------
   * exec_eval_simple_expr -		Evaluate a simple expression returning
   *								a Datum by directly calling ExecEvalExpr().
   *
   * If successful, store results into *result, *isNull, *rettype, *rettypmod
   * and return true.  If the expression cannot be handled by simple evaluation,
   * return false.
   *
   * Because we only store one execution tree for a simple expression, we
   * can't handle recursion cases.  So, if we see the tree is already busy
   * with an evaluation in the current xact, we just return false and let the
   * caller run the expression the hard way.  (Other alternatives such as
   * creating a new tree for a recursive call either introduce memory leaks,
   * or add enough bookkeeping to be doubtful wins anyway.)  Another case that
   * is covered by the expr_simple_in_use test is where a previous execution
   * of the tree was aborted by an error: the tree may contain bogus state
   * so we dare not re-use it.
   *
   * It is possible that we'd need to replan a simple expression; for example,
   * someone might redefine a SQL function that had been inlined into the simple
   * expression.  That cannot cause a simple expression to become non-simple (or
   * vice versa), but we do have to handle replacing the expression tree.
   * Fortunately it's normally inexpensive to call SPI_plan_get_cached_plan for
   * a simple expression.
   *
   * Note: if pass-by-reference, the result is in the eval_mcontext.
   * It will be freed when exec_eval_cleanup is done.
   * ----------
   */
  static bool
  exec_eval_simple_expr(PLpgSQL_execstate *estate,
  					  PLpgSQL_expr *expr,
  					  Datum *result,
  					  bool *isNull,
  					  Oid *rettype,
  					  int32 *rettypmod)
  {
  	ExprContext *econtext = estate->eval_econtext;
  	LocalTransactionId curlxid = MyProc->lxid;
  	CachedPlan *cplan;
  	void	   *save_setup_arg;
  	bool		need_snapshot;
  	MemoryContext oldcontext;
  
  	/*
  	 * Forget it if expression wasn't simple before.
  	 */
  	if (expr->expr_simple_expr == NULL)
  		return false;
  
  	/*
  	 * If expression is in use in current xact, don't touch it.
  	 */
  	if (expr->expr_simple_in_use && expr->expr_simple_lxid == curlxid)
  		return false;
  
  	/*
  	 * Revalidate cached plan, so that we will notice if it became stale. (We
  	 * need to hold a refcount while using the plan, anyway.)  If replanning
  	 * is needed, do that work in the eval_mcontext.
  	 */
  	oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate));
  	cplan = SPI_plan_get_cached_plan(expr->plan);
  	MemoryContextSwitchTo(oldcontext);
  
  	/*
  	 * We can't get a failure here, because the number of CachedPlanSources in
  	 * the SPI plan can't change from what exec_simple_check_plan saw; it's a
  	 * property of the raw parsetree generated from the query text.
  	 */
  	Assert(cplan != NULL);
  
  	/* If it got replanned, update our copy of the simple expression */
  	if (cplan->generation != expr->expr_simple_generation)
  	{
  		exec_save_simple_expr(expr, cplan);
  		/* better recheck r/w safety, as it could change due to inlining */
  		if (expr->rwparam >= 0)
  			exec_check_rw_parameter(expr, expr->rwparam);
  	}
  
  	/*
  	 * Pass back previously-determined result type.
  	 */
  	*rettype = expr->expr_simple_type;
  	*rettypmod = expr->expr_simple_typmod;
  
  	/*
  	 * Set up ParamListInfo to pass to executor.  For safety, save and restore
  	 * estate->paramLI->parserSetupArg around our use of the param list.
  	 */
  	save_setup_arg = estate->paramLI->parserSetupArg;
  
  	econtext->ecxt_param_list_info = setup_param_list(estate, expr);
  
  	/*
  	 * Prepare the expression for execution, if it's not been done already in
  	 * the current transaction.  (This will be forced to happen if we called
  	 * exec_save_simple_expr above.)
  	 */
  	if (expr->expr_simple_lxid != curlxid)
  	{
  		oldcontext = MemoryContextSwitchTo(estate->simple_eval_estate->es_query_cxt);
  		expr->expr_simple_state =
  			ExecInitExprWithParams(expr->expr_simple_expr,
  								   econtext->ecxt_param_list_info);
  		expr->expr_simple_in_use = false;
  		expr->expr_simple_lxid = curlxid;
  		MemoryContextSwitchTo(oldcontext);
  	}
  
  	/*
  	 * We have to do some of the things SPI_execute_plan would do, in
  	 * particular push a new snapshot so that stable functions within the
  	 * expression can see updates made so far by our own function.  However,
  	 * we can skip doing that (and just invoke the expression with the same
  	 * snapshot passed to our function) in some cases, which is useful because
  	 * it's quite expensive relative to the cost of a simple expression.  We
  	 * can skip it if the expression contains no stable or volatile functions;
  	 * immutable functions shouldn't need to see our updates.  Also, if this
  	 * is a read-only function, we haven't made any updates so again it's okay
  	 * to skip.
  	 */
  	oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate));
  	need_snapshot = (expr->expr_simple_mutable && !estate->readonly_func);
  	if (need_snapshot)
  	{
  		CommandCounterIncrement();
  		PushActiveSnapshot(GetTransactionSnapshot());
  	}
  
  	/*
  	 * Mark expression as busy for the duration of the ExecEvalExpr call.
  	 */
  	expr->expr_simple_in_use = true;
  
  	/*
  	 * Finally we can call the executor to evaluate the expression
  	 */
  	*result = ExecEvalExpr(expr->expr_simple_state,
  						   econtext,
  						   isNull);
  
  	/* Assorted cleanup */
  	expr->expr_simple_in_use = false;
  
  	econtext->ecxt_param_list_info = NULL;
  
  	estate->paramLI->parserSetupArg = save_setup_arg;
  
  	if (need_snapshot)
  		PopActiveSnapshot();
  
  	MemoryContextSwitchTo(oldcontext);
  
  	/*
  	 * Now we can release our refcount on the cached plan.
  	 */
  	ReleaseCachedPlan(cplan, true);
  
  	/*
  	 * That's it.
  	 */
  	return true;
  }
  
  
  /*
   * Create a ParamListInfo to pass to SPI
   *
   * We use a single ParamListInfo struct for all SPI calls made from this
   * estate; it contains no per-param data, just hook functions, so it's
   * effectively read-only for SPI.
   *
   * An exception from pure read-only-ness is that the parserSetupArg points
   * to the specific PLpgSQL_expr being evaluated.  This is not an issue for
   * statement-level callers, but lower-level callers must save and restore
   * estate->paramLI->parserSetupArg just in case there's an active evaluation
   * at an outer call level.  (A plausible alternative design would be to
   * create a ParamListInfo struct for each PLpgSQL_expr, but for the moment
   * that seems like a waste of memory.)
   */
  static ParamListInfo
  setup_param_list(PLpgSQL_execstate *estate, PLpgSQL_expr *expr)
  {
  	ParamListInfo paramLI;
  
  	/*
  	 * We must have created the SPIPlan already (hence, query text has been
  	 * parsed/analyzed at least once); else we cannot rely on expr->paramnos.
  	 */
  	Assert(expr->plan != NULL);
  
  	/*
  	 * We only need a ParamListInfo if the expression has parameters.  In
  	 * principle we should test with bms_is_empty(), but we use a not-null
  	 * test because it's faster.  In current usage bits are never removed from
  	 * expr->paramnos, only added, so this test is correct anyway.
  	 */
  	if (expr->paramnos)
  	{
  		/* Use the common ParamListInfo */
  		paramLI = estate->paramLI;
  
  		/*
  		 * Set up link to active expr where the hook functions can find it.
  		 * Callers must save and restore parserSetupArg if there is any chance
  		 * that they are interrupting an active use of parameters.
  		 */
  		paramLI->parserSetupArg = (void *) expr;
  
  		/*
  		 * Also make sure this is set before parser hooks need it.  There is
  		 * no need to save and restore, since the value is always correct once
  		 * set.  (Should be set already, but let's be sure.)
  		 */
  		expr->func = estate->func;
  	}
  	else
  	{
  		/*
  		 * Expression requires no parameters.  Be sure we represent this case
  		 * as a NULL ParamListInfo, so that plancache.c knows there is no
  		 * point in a custom plan.
  		 */
  		paramLI = NULL;
  	}
  	return paramLI;
  }
  
  /*
   * plpgsql_param_fetch		paramFetch callback for dynamic parameter fetch
   *
   * We always use the caller's workspace to construct the returned struct.
   *
   * Note: this is no longer used during query execution.  It is used during
   * planning (with speculative == true) and when the ParamListInfo we supply
   * to the executor is copied into a cursor portal or transferred to a
   * parallel child process.
   */
  static ParamExternData *
  plpgsql_param_fetch(ParamListInfo params,
  					int paramid, bool speculative,
  					ParamExternData *prm)
  {
  	int			dno;
  	PLpgSQL_execstate *estate;
  	PLpgSQL_expr *expr;
  	PLpgSQL_datum *datum;
  	bool		ok = true;
  	int32		prmtypmod;
  
  	/* paramid's are 1-based, but dnos are 0-based */
  	dno = paramid - 1;
  	Assert(dno >= 0 && dno < params->numParams);
  
  	/* fetch back the hook data */
  	estate = (PLpgSQL_execstate *) params->paramFetchArg;
  	expr = (PLpgSQL_expr *) params->parserSetupArg;
  	Assert(params->numParams == estate->ndatums);
  
  	/* now we can access the target datum */
  	datum = estate->datums[dno];
  
  	/*
  	 * Since copyParamList() or SerializeParamList() will try to materialize
  	 * every single parameter slot, it's important to return a dummy param
  	 * when asked for a datum that's not supposed to be used by this SQL
  	 * expression.  Otherwise we risk failures in exec_eval_datum(), or
  	 * copying a lot more data than necessary.
  	 */
  	if (!bms_is_member(dno, expr->paramnos))
  		ok = false;
  
  	/*
  	 * If the access is speculative, we prefer to return no data rather than
  	 * to fail in exec_eval_datum().  Check the likely failure cases.
  	 */
  	else if (speculative)
  	{
  		switch (datum->dtype)
  		{
  			case PLPGSQL_DTYPE_VAR:
  			case PLPGSQL_DTYPE_PROMISE:
  				/* always safe */
  				break;
  
  			case PLPGSQL_DTYPE_ROW:
  				/* should be safe in all interesting cases */
  				break;
  
  			case PLPGSQL_DTYPE_REC:
  				/* always safe (might return NULL, that's fine) */
  				break;
  
  			case PLPGSQL_DTYPE_RECFIELD:
  				{
  					PLpgSQL_recfield *recfield = (PLpgSQL_recfield *) datum;
  					PLpgSQL_rec *rec;
  
  					rec = (PLpgSQL_rec *) (estate->datums[recfield->recparentno]);
  
  					/*
  					 * If record variable is NULL, don't risk anything.
  					 */
  					if (rec->erh == NULL)
  						ok = false;
  
  					/*
  					 * Look up the field's properties if we have not already,
  					 * or if the tuple descriptor ID changed since last time.
  					 */
  					else if (unlikely(recfield->rectupledescid != rec->erh->er_tupdesc_id))
  					{
  						if (expanded_record_lookup_field(rec->erh,
  														 recfield->fieldname,
  														 &recfield->finfo))
  							recfield->rectupledescid = rec->erh->er_tupdesc_id;
  						else
  							ok = false;
  					}
  					break;
  				}
  
  			default:
  				ok = false;
  				break;
  		}
  	}
  
  	/* Return "no such parameter" if not ok */
  	if (!ok)
  	{
  		prm->value = (Datum) 0;
  		prm->isnull = true;
  		prm->pflags = 0;
  		prm->ptype = InvalidOid;
  		return prm;
  	}
  
  	/* OK, evaluate the value and store into the return struct */
  	exec_eval_datum(estate, datum,
  					&prm->ptype, &prmtypmod,
  					&prm->value, &prm->isnull);
  	/* We can always mark params as "const" for executor's purposes */
  	prm->pflags = PARAM_FLAG_CONST;
  
  	/*
  	 * If it's a read/write expanded datum, convert reference to read-only,
  	 * unless it's safe to pass as read-write.
  	 */
  	if (dno != expr->rwparam)
  	{
  		if (datum->dtype == PLPGSQL_DTYPE_VAR)
  			prm->value = MakeExpandedObjectReadOnly(prm->value,
  													prm->isnull,
  													((PLpgSQL_var *) datum)->datatype->typlen);
  		else if (datum->dtype == PLPGSQL_DTYPE_REC)
  			prm->value = MakeExpandedObjectReadOnly(prm->value,
  													prm->isnull,
  													-1);
  	}
  
  	return prm;
  }
  
  /*
   * plpgsql_param_compile		paramCompile callback for plpgsql parameters
   */
  static void
  plpgsql_param_compile(ParamListInfo params, Param *param,
  					  ExprState *state,
  					  Datum *resv, bool *resnull)
  {
  	PLpgSQL_execstate *estate;
  	PLpgSQL_expr *expr;
  	int			dno;
  	PLpgSQL_datum *datum;
  	ExprEvalStep scratch;
  
  	/* fetch back the hook data */
  	estate = (PLpgSQL_execstate *) params->paramFetchArg;
  	expr = (PLpgSQL_expr *) params->parserSetupArg;
  
  	/* paramid's are 1-based, but dnos are 0-based */
  	dno = param->paramid - 1;
  	Assert(dno >= 0 && dno < estate->ndatums);
  
  	/* now we can access the target datum */
  	datum = estate->datums[dno];
  
  	scratch.opcode = EEOP_PARAM_CALLBACK;
  	scratch.resvalue = resv;
  	scratch.resnull = resnull;
  
  	/*
  	 * Select appropriate eval function.  It seems worth special-casing
  	 * DTYPE_VAR and DTYPE_RECFIELD for performance.  Also, we can determine
  	 * in advance whether MakeExpandedObjectReadOnly() will be required.
  	 * Currently, only VAR/PROMISE and REC datums could contain read/write
  	 * expanded objects.
  	 */
  	if (datum->dtype == PLPGSQL_DTYPE_VAR)
  	{
  		if (dno != expr->rwparam &&
  			((PLpgSQL_var *) datum)->datatype->typlen == -1)
  			scratch.d.cparam.paramfunc = plpgsql_param_eval_var_ro;
  		else
  			scratch.d.cparam.paramfunc = plpgsql_param_eval_var;
  	}
  	else if (datum->dtype == PLPGSQL_DTYPE_RECFIELD)
  		scratch.d.cparam.paramfunc = plpgsql_param_eval_recfield;
  	else if (datum->dtype == PLPGSQL_DTYPE_PROMISE)
  	{
  		if (dno != expr->rwparam &&
  			((PLpgSQL_var *) datum)->datatype->typlen == -1)
  			scratch.d.cparam.paramfunc = plpgsql_param_eval_generic_ro;
  		else
  			scratch.d.cparam.paramfunc = plpgsql_param_eval_generic;
  	}
  	else if (datum->dtype == PLPGSQL_DTYPE_REC &&
  			 dno != expr->rwparam)
  		scratch.d.cparam.paramfunc = plpgsql_param_eval_generic_ro;
  	else
  		scratch.d.cparam.paramfunc = plpgsql_param_eval_generic;
  
  	/*
  	 * Note: it's tempting to use paramarg to store the estate pointer and
  	 * thereby save an indirection or two in the eval functions.  But that
  	 * doesn't work because the compiled expression might be used with
  	 * different estates for the same PL/pgSQL function.
  	 */
  	scratch.d.cparam.paramarg = NULL;
  	scratch.d.cparam.paramid = param->paramid;
  	scratch.d.cparam.paramtype = param->paramtype;
  	ExprEvalPushStep(state, &scratch);
  }
  
  /*
   * plpgsql_param_eval_var		evaluation of EEOP_PARAM_CALLBACK step
   *
   * This is specialized to the case of DTYPE_VAR variables for which
   * we do not need to invoke MakeExpandedObjectReadOnly.
   */
  static void
  plpgsql_param_eval_var(ExprState *state, ExprEvalStep *op,
  					   ExprContext *econtext)
  {
  	ParamListInfo params;
  	PLpgSQL_execstate *estate;
  	int			dno = op->d.cparam.paramid - 1;
  	PLpgSQL_var *var;
  
  	/* fetch back the hook data */
  	params = econtext->ecxt_param_list_info;
  	estate = (PLpgSQL_execstate *) params->paramFetchArg;
  	Assert(dno >= 0 && dno < estate->ndatums);
  
  	/* now we can access the target datum */
  	var = (PLpgSQL_var *) estate->datums[dno];
  	Assert(var->dtype == PLPGSQL_DTYPE_VAR);
  
  	/* inlined version of exec_eval_datum() */
  	*op->resvalue = var->value;
  	*op->resnull = var->isnull;
  
  	/* safety check -- an assertion should be sufficient */
  	Assert(var->datatype->typoid == op->d.cparam.paramtype);
  }
  
  /*
   * plpgsql_param_eval_var_ro		evaluation of EEOP_PARAM_CALLBACK step
   *
   * This is specialized to the case of DTYPE_VAR variables for which
   * we need to invoke MakeExpandedObjectReadOnly.
   */
  static void
  plpgsql_param_eval_var_ro(ExprState *state, ExprEvalStep *op,
  						  ExprContext *econtext)
  {
  	ParamListInfo params;
  	PLpgSQL_execstate *estate;
  	int			dno = op->d.cparam.paramid - 1;
  	PLpgSQL_var *var;
  
  	/* fetch back the hook data */
  	params = econtext->ecxt_param_list_info;
  	estate = (PLpgSQL_execstate *) params->paramFetchArg;
  	Assert(dno >= 0 && dno < estate->ndatums);
  
  	/* now we can access the target datum */
  	var = (PLpgSQL_var *) estate->datums[dno];
  	Assert(var->dtype == PLPGSQL_DTYPE_VAR);
  
  	/*
  	 * Inlined version of exec_eval_datum() ... and while we're at it, force
  	 * expanded datums to read-only.
  	 */
  	*op->resvalue = MakeExpandedObjectReadOnly(var->value,
  											   var->isnull,
  											   -1);
  	*op->resnull = var->isnull;
  
  	/* safety check -- an assertion should be sufficient */
  	Assert(var->datatype->typoid == op->d.cparam.paramtype);
  }
  
  /*
   * plpgsql_param_eval_recfield		evaluation of EEOP_PARAM_CALLBACK step
   *
   * This is specialized to the case of DTYPE_RECFIELD variables, for which
   * we never need to invoke MakeExpandedObjectReadOnly.
   */
  static void
  plpgsql_param_eval_recfield(ExprState *state, ExprEvalStep *op,
  							ExprContext *econtext)
  {
  	ParamListInfo params;
  	PLpgSQL_execstate *estate;
  	int			dno = op->d.cparam.paramid - 1;
  	PLpgSQL_recfield *recfield;
  	PLpgSQL_rec *rec;
  	ExpandedRecordHeader *erh;
  
  	/* fetch back the hook data */
  	params = econtext->ecxt_param_list_info;
  	estate = (PLpgSQL_execstate *) params->paramFetchArg;
  	Assert(dno >= 0 && dno < estate->ndatums);
  
  	/* now we can access the target datum */
  	recfield = (PLpgSQL_recfield *) estate->datums[dno];
  	Assert(recfield->dtype == PLPGSQL_DTYPE_RECFIELD);
  
  	/* inline the relevant part of exec_eval_datum */
  	rec = (PLpgSQL_rec *) (estate->datums[recfield->recparentno]);
  	erh = rec->erh;
  
  	/*
  	 * If record variable is NULL, instantiate it if it has a named composite
  	 * type, else complain.  (This won't change the logical state of the
  	 * record: it's still NULL.)
  	 */
  	if (erh == NULL)
  	{
  		instantiate_empty_record_variable(estate, rec);
  		erh = rec->erh;
  	}
  
  	/*
  	 * Look up the field's properties if we have not already, or if the tuple
  	 * descriptor ID changed since last time.
  	 */
  	if (unlikely(recfield->rectupledescid != erh->er_tupdesc_id))
  	{
  		if (!expanded_record_lookup_field(erh,
  										  recfield->fieldname,
  										  &recfield->finfo))
  			ereport(ERROR,
  					(errcode(ERRCODE_UNDEFINED_COLUMN),
  					 errmsg("record \"%s\" has no field \"%s\"",
  							rec->refname, recfield->fieldname)));
  		recfield->rectupledescid = erh->er_tupdesc_id;
  	}
  
  	/* OK to fetch the field value. */
  	*op->resvalue = expanded_record_get_field(erh,
  											  recfield->finfo.fnumber,
  											  op->resnull);
  
  	/* safety check -- needed for, eg, record fields */
  	if (unlikely(recfield->finfo.ftypeid != op->d.cparam.paramtype))
  		ereport(ERROR,
  				(errcode(ERRCODE_DATATYPE_MISMATCH),
  				 errmsg("type of parameter %d (%s) does not match that when preparing the plan (%s)",
  						op->d.cparam.paramid,
  						format_type_be(recfield->finfo.ftypeid),
  						format_type_be(op->d.cparam.paramtype))));
  }
  
  /*
   * plpgsql_param_eval_generic		evaluation of EEOP_PARAM_CALLBACK step
   *
   * This handles all variable types, but assumes we do not need to invoke
   * MakeExpandedObjectReadOnly.
   */
  static void
  plpgsql_param_eval_generic(ExprState *state, ExprEvalStep *op,
  						   ExprContext *econtext)
  {
  	ParamListInfo params;
  	PLpgSQL_execstate *estate;
  	int			dno = op->d.cparam.paramid - 1;
  	PLpgSQL_datum *datum;
  	Oid			datumtype;
  	int32		datumtypmod;
  
  	/* fetch back the hook data */
  	params = econtext->ecxt_param_list_info;
  	estate = (PLpgSQL_execstate *) params->paramFetchArg;
  	Assert(dno >= 0 && dno < estate->ndatums);
  
  	/* now we can access the target datum */
  	datum = estate->datums[dno];
  
  	/* fetch datum's value */
  	exec_eval_datum(estate, datum,
  					&datumtype, &datumtypmod,
  					op->resvalue, op->resnull);
  
  	/* safety check -- needed for, eg, record fields */
  	if (unlikely(datumtype != op->d.cparam.paramtype))
  		ereport(ERROR,
  				(errcode(ERRCODE_DATATYPE_MISMATCH),
  				 errmsg("type of parameter %d (%s) does not match that when preparing the plan (%s)",
  						op->d.cparam.paramid,
  						format_type_be(datumtype),
  						format_type_be(op->d.cparam.paramtype))));
  }
  
  /*
   * plpgsql_param_eval_generic_ro	evaluation of EEOP_PARAM_CALLBACK step
   *
   * This handles all variable types, but assumes we need to invoke
   * MakeExpandedObjectReadOnly (hence, variable must be of a varlena type).
   */
  static void
  plpgsql_param_eval_generic_ro(ExprState *state, ExprEvalStep *op,
  							  ExprContext *econtext)
  {
  	ParamListInfo params;
  	PLpgSQL_execstate *estate;
  	int			dno = op->d.cparam.paramid - 1;
  	PLpgSQL_datum *datum;
  	Oid			datumtype;
  	int32		datumtypmod;
  
  	/* fetch back the hook data */
  	params = econtext->ecxt_param_list_info;
  	estate = (PLpgSQL_execstate *) params->paramFetchArg;
  	Assert(dno >= 0 && dno < estate->ndatums);
  
  	/* now we can access the target datum */
  	datum = estate->datums[dno];
  
  	/* fetch datum's value */
  	exec_eval_datum(estate, datum,
  					&datumtype, &datumtypmod,
  					op->resvalue, op->resnull);
  
  	/* safety check -- needed for, eg, record fields */
  	if (unlikely(datumtype != op->d.cparam.paramtype))
  		ereport(ERROR,
  				(errcode(ERRCODE_DATATYPE_MISMATCH),
  				 errmsg("type of parameter %d (%s) does not match that when preparing the plan (%s)",
  						op->d.cparam.paramid,
  						format_type_be(datumtype),
  						format_type_be(op->d.cparam.paramtype))));
  
  	/* force the value to read-only */
  	*op->resvalue = MakeExpandedObjectReadOnly(*op->resvalue,
  											   *op->resnull,
  											   -1);
  }
  
  
  /*
   * exec_move_row			Move one tuple's values into a record or row
   *
   * tup and tupdesc may both be NULL if we're just assigning an indeterminate
   * composite NULL to the target.  Alternatively, can have tup be NULL and
   * tupdesc not NULL, in which case we assign a row of NULLs to the target.
   *
   * Since this uses the mcontext for workspace, caller should eventually call
   * exec_eval_cleanup to prevent long-term memory leaks.
   */
  static void
  exec_move_row(PLpgSQL_execstate *estate,
  			  PLpgSQL_variable *target,
  			  HeapTuple tup, TupleDesc tupdesc)
  {
  	ExpandedRecordHeader *newerh = NULL;
  
  	/*
  	 * If target is RECORD, we may be able to avoid field-by-field processing.
  	 */
  	if (target->dtype == PLPGSQL_DTYPE_REC)
  	{
  		PLpgSQL_rec *rec = (PLpgSQL_rec *) target;
  
  		/*
  		 * If we have no source tupdesc, just set the record variable to NULL.
  		 * (If we have a source tupdesc but not a tuple, we'll set the
  		 * variable to a row of nulls, instead.  This is odd perhaps, but
  		 * backwards compatible.)
  		 */
  		if (tupdesc == NULL)
  		{
  			if (rec->datatype &&
  				rec->datatype->typtype == TYPTYPE_DOMAIN)
  			{
  				/*
  				 * If it's a composite domain, NULL might not be a legal
  				 * value, so we instead need to make an empty expanded record
  				 * and ensure that domain type checking gets done.  If there
  				 * is already an expanded record, piggyback on its lookups.
  				 */
  				newerh = make_expanded_record_for_rec(estate, rec,
  													  NULL, rec->erh);
  				expanded_record_set_tuple(newerh, NULL, false, false);
  				assign_record_var(estate, rec, newerh);
  			}
  			else
  			{
  				/* Just clear it to NULL */
  				if (rec->erh)
  					DeleteExpandedObject(ExpandedRecordGetDatum(rec->erh));
  				rec->erh = NULL;
  			}
  			return;
  		}
  
  		/*
  		 * Build a new expanded record with appropriate tupdesc.
  		 */
  		newerh = make_expanded_record_for_rec(estate, rec, tupdesc, NULL);
  
  		/*
  		 * If the rowtypes match, or if we have no tuple anyway, we can
  		 * complete the assignment without field-by-field processing.
  		 *
  		 * The tests here are ordered more or less in order of cheapness.  We
  		 * can easily detect it will work if the target is declared RECORD or
  		 * has the same typeid as the source.  But when assigning from a query
  		 * result, it's common to have a source tupdesc that's labeled RECORD
  		 * but is actually physically compatible with a named-composite-type
  		 * target, so it's worth spending extra cycles to check for that.
  		 */
  		if (rec->rectypeid == RECORDOID ||
  			rec->rectypeid == tupdesc->tdtypeid ||
  			!HeapTupleIsValid(tup) ||
  			compatible_tupdescs(tupdesc, expanded_record_get_tupdesc(newerh)))
  		{
  			if (!HeapTupleIsValid(tup))
  			{
  				/* No data, so force the record into all-nulls state */
  				deconstruct_expanded_record(newerh);
  			}
  			else
  			{
  				/* No coercion is needed, so just assign the row value */
  				expanded_record_set_tuple(newerh, tup, true, !estate->atomic);
  			}
  
  			/* Complete the assignment */
  			assign_record_var(estate, rec, newerh);
  
  			return;
  		}
  	}
  
  	/*
  	 * Otherwise, deconstruct the tuple and do field-by-field assignment,
  	 * using exec_move_row_from_fields.
  	 */
  	if (tupdesc && HeapTupleIsValid(tup))
  	{
  		int			td_natts = tupdesc->natts;
  		Datum	   *values;
  		bool	   *nulls;
  		Datum		values_local[64];
  		bool		nulls_local[64];
  
  		/*
  		 * Need workspace arrays.  If td_natts is small enough, use local
  		 * arrays to save doing a palloc.  Even if it's not small, we can
  		 * allocate both the Datum and isnull arrays in one palloc chunk.
  		 */
  		if (td_natts <= lengthof(values_local))
  		{
  			values = values_local;
  			nulls = nulls_local;
  		}
  		else
  		{
  			char	   *chunk;
  
  			chunk = eval_mcontext_alloc(estate,
  										td_natts * (sizeof(Datum) + sizeof(bool)));
  			values = (Datum *) chunk;
  			nulls = (bool *) (chunk + td_natts * sizeof(Datum));
  		}
  
  		heap_deform_tuple(tup, tupdesc, values, nulls);
  
  		exec_move_row_from_fields(estate, target, newerh,
  								  values, nulls, tupdesc);
  	}
  	else
  	{
  		/*
  		 * Assign all-nulls.
  		 */
  		exec_move_row_from_fields(estate, target, newerh,
  								  NULL, NULL, NULL);
  	}
  }
  
  /*
   * Verify that a PLpgSQL_rec's rectypeid is up-to-date.
   */
  static void
  revalidate_rectypeid(PLpgSQL_rec *rec)
  {
  	PLpgSQL_type *typ = rec->datatype;
  	TypeCacheEntry *typentry;
  
  	if (rec->rectypeid == RECORDOID)
  		return;					/* it's RECORD, so nothing to do */
  	Assert(typ != NULL);
  	if (typ->tcache &&
  		typ->tcache->tupDesc_identifier == typ->tupdesc_id)
  	{
  		/*
  		 * Although *typ is known up-to-date, it's possible that rectypeid
  		 * isn't, because *rec is cloned during each function startup from a
  		 * copy that we don't have a good way to update.  Hence, forcibly fix
  		 * rectypeid before returning.
  		 */
  		rec->rectypeid = typ->typoid;
  		return;
  	}
  
  	/*
  	 * typcache entry has suffered invalidation, so re-look-up the type name
  	 * if possible, and then recheck the type OID.  If we don't have a
  	 * TypeName, then we just have to soldier on with the OID we've got.
  	 */
  	if (typ->origtypname != NULL)
  	{
  		/* this bit should match parse_datatype() in pl_gram.y */
  		typenameTypeIdAndMod(NULL, typ->origtypname,
  							 &typ->typoid,
  							 &typ->atttypmod);
  	}
  
  	/* this bit should match build_datatype() in pl_comp.c */
  	typentry = lookup_type_cache(typ->typoid,
  								 TYPECACHE_TUPDESC |
  								 TYPECACHE_DOMAIN_BASE_INFO);
  	if (typentry->typtype == TYPTYPE_DOMAIN)
  		typentry = lookup_type_cache(typentry->domainBaseType,
  									 TYPECACHE_TUPDESC);
  	if (typentry->tupDesc == NULL)
  	{
  		/*
  		 * If we get here, user tried to replace a composite type with a
  		 * non-composite one.  We're not gonna support that.
  		 */
  		ereport(ERROR,
  				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  				 errmsg("type %s is not composite",
  						format_type_be(typ->typoid))));
  	}
  
  	/*
  	 * Update tcache and tupdesc_id.  Since we don't support changing to a
  	 * non-composite type, none of the rest of *typ needs to change.
  	 */
  	typ->tcache = typentry;
  	typ->tupdesc_id = typentry->tupDesc_identifier;
  
  	/*
  	 * Update *rec, too.  (We'll deal with subsidiary RECFIELDs as needed.)
  	 */
  	rec->rectypeid = typ->typoid;
  }
  
  /*
   * Build an expanded record object suitable for assignment to "rec".
   *
   * Caller must supply either a source tuple descriptor or a source expanded
   * record (not both).  If the record variable has declared type RECORD,
   * it'll adopt the source's rowtype.  Even if it doesn't, we may be able to
   * piggyback on a source expanded record to save a typcache lookup.
   *
   * Caller must fill the object with data, then do assign_record_var().
   *
   * The new record is initially put into the mcontext, so it will be cleaned up
   * if we fail before reaching assign_record_var().
   */
  static ExpandedRecordHeader *
  make_expanded_record_for_rec(PLpgSQL_execstate *estate,
  							 PLpgSQL_rec *rec,
  							 TupleDesc srctupdesc,
  							 ExpandedRecordHeader *srcerh)
  {
  	ExpandedRecordHeader *newerh;
  	MemoryContext mcontext = get_eval_mcontext(estate);
  
  	if (rec->rectypeid != RECORDOID)
  	{
  		/*
  		 * Make sure rec->rectypeid is up-to-date before using it.
  		 */
  		revalidate_rectypeid(rec);
  
  		/*
  		 * New record must be of desired type, but maybe srcerh has already
  		 * done all the same lookups.
  		 */
  		if (srcerh && rec->rectypeid == srcerh->er_decltypeid)
  			newerh = make_expanded_record_from_exprecord(srcerh,
  														 mcontext);
  		else
  			newerh = make_expanded_record_from_typeid(rec->rectypeid, -1,
  													  mcontext);
  	}
  	else
  	{
  		/*
  		 * We'll adopt the input tupdesc.  We can still use
  		 * make_expanded_record_from_exprecord, if srcerh isn't a composite
  		 * domain.  (If it is, we effectively adopt its base type.)
  		 */
  		if (srcerh && !ExpandedRecordIsDomain(srcerh))
  			newerh = make_expanded_record_from_exprecord(srcerh,
  														 mcontext);
  		else
  		{
  			if (!srctupdesc)
  				srctupdesc = expanded_record_get_tupdesc(srcerh);
  			newerh = make_expanded_record_from_tupdesc(srctupdesc,
  													   mcontext);
  		}
  	}
  
  	return newerh;
  }
  
  /*
   * exec_move_row_from_fields	Move arrays of field values into a record or row
   *
   * When assigning to a record, the caller must have already created a suitable
   * new expanded record object, newerh.  Pass NULL when assigning to a row.
   *
   * tupdesc describes the input row, which might have different column
   * types and/or different dropped-column positions than the target.
   * values/nulls/tupdesc can all be NULL if we just want to assign nulls to
   * all fields of the record or row.
   *
   * Since this uses the mcontext for workspace, caller should eventually call
   * exec_eval_cleanup to prevent long-term memory leaks.
   */
  static void
  exec_move_row_from_fields(PLpgSQL_execstate *estate,
  						  PLpgSQL_variable *target,
  						  ExpandedRecordHeader *newerh,
  						  Datum *values, bool *nulls,
  						  TupleDesc tupdesc)
  {
  	int			td_natts = tupdesc ? tupdesc->natts : 0;
  	int			fnum;
  	int			anum;
  	int			strict_multiassignment_level = 0;
  
  	/*
  	 * The extra check strict strict_multi_assignment can be active, only when
  	 * input tupdesc is specified.
  	 */
  	if (tupdesc != NULL)
  	{
  		if (plpgsql_extra_errors & PLPGSQL_XCHECK_STRICTMULTIASSIGNMENT)
  			strict_multiassignment_level = ERROR;
  		else if (plpgsql_extra_warnings & PLPGSQL_XCHECK_STRICTMULTIASSIGNMENT)
  			strict_multiassignment_level = WARNING;
  	}
  
  	/* Handle RECORD-target case */
  	if (target->dtype == PLPGSQL_DTYPE_REC)
  	{
  		PLpgSQL_rec *rec = (PLpgSQL_rec *) target;
  		TupleDesc	var_tupdesc;
  		Datum		newvalues_local[64];
  		bool		newnulls_local[64];
  
  		Assert(newerh != NULL); /* caller must have built new object */
  
  		var_tupdesc = expanded_record_get_tupdesc(newerh);
  
  		/*
  		 * Coerce field values if needed.  This might involve dealing with
  		 * different sets of dropped columns and/or coercing individual column
  		 * types.  That's sort of a pain, but historically plpgsql has allowed
  		 * it, so we preserve the behavior.  However, it's worth a quick check
  		 * to see if the tupdescs are identical.  (Since expandedrecord.c
  		 * prefers to use refcounted tupdescs from the typcache, expanded
  		 * records with the same rowtype will have pointer-equal tupdescs.)
  		 */
  		if (var_tupdesc != tupdesc)
  		{
  			int			vtd_natts = var_tupdesc->natts;
  			Datum	   *newvalues;
  			bool	   *newnulls;
  
  			/*
  			 * Need workspace arrays.  If vtd_natts is small enough, use local
  			 * arrays to save doing a palloc.  Even if it's not small, we can
  			 * allocate both the Datum and isnull arrays in one palloc chunk.
  			 */
  			if (vtd_natts <= lengthof(newvalues_local))
  			{
  				newvalues = newvalues_local;
  				newnulls = newnulls_local;
  			}
  			else
  			{
  				char	   *chunk;
  
  				chunk = eval_mcontext_alloc(estate,
  											vtd_natts * (sizeof(Datum) + sizeof(bool)));
  				newvalues = (Datum *) chunk;
  				newnulls = (bool *) (chunk + vtd_natts * sizeof(Datum));
  			}
  
  			/* Walk over destination columns */
  			anum = 0;
  			for (fnum = 0; fnum < vtd_natts; fnum++)
  			{
  				Form_pg_attribute attr = TupleDescAttr(var_tupdesc, fnum);
  				Datum		value;
  				bool		isnull;
  				Oid			valtype;
  				int32		valtypmod;
  
  				if (attr->attisdropped)
  				{
  					/* expanded_record_set_fields should ignore this column */
  					continue;	/* skip dropped column in record */
  				}
  
  				while (anum < td_natts &&
  					   TupleDescAttr(tupdesc, anum)->attisdropped)
  					anum++;		/* skip dropped column in tuple */
  
  				if (anum < td_natts)
  				{
  					value = values[anum];
  					isnull = nulls[anum];
  					valtype = TupleDescAttr(tupdesc, anum)->atttypid;
  					valtypmod = TupleDescAttr(tupdesc, anum)->atttypmod;
  					anum++;
  				}
  				else
  				{
  					/* no source for destination column */
  					value = (Datum) 0;
  					isnull = true;
  					valtype = UNKNOWNOID;
  					valtypmod = -1;
  
  					/* When source value is missing */
  					if (strict_multiassignment_level)
  						ereport(strict_multiassignment_level,
  								(errcode(ERRCODE_DATATYPE_MISMATCH),
  								 errmsg("number of source and target fields in assignment does not match"),
  						/* translator: %s represents a name of an extra check */
  								 errdetail("%s check of %s is active.",
  										   "strict_multi_assignment",
  										   strict_multiassignment_level == ERROR ? "extra_errors" :
  										   "extra_warnings"),
  								 errhint("Make sure the query returns the exact list of columns.")));
  				}
  
  				/* Cast the new value to the right type, if needed. */
  				newvalues[fnum] = exec_cast_value(estate,
  												  value,
  												  &isnull,
  												  valtype,
  												  valtypmod,
  												  attr->atttypid,
  												  attr->atttypmod);
  				newnulls[fnum] = isnull;
  			}
  
  			/*
  			 * When strict_multiassignment extra check is active, then ensure
  			 * there are no unassigned source attributes.
  			 */
  			if (strict_multiassignment_level && anum < td_natts)
  			{
  				/* skip dropped columns in the source descriptor */
  				while (anum < td_natts &&
  					   TupleDescAttr(tupdesc, anum)->attisdropped)
  					anum++;
  
  				if (anum < td_natts)
  					ereport(strict_multiassignment_level,
  							(errcode(ERRCODE_DATATYPE_MISMATCH),
  							 errmsg("number of source and target fields in assignment does not match"),
  					/* translator: %s represents a name of an extra check */
  							 errdetail("%s check of %s is active.",
  									   "strict_multi_assignment",
  									   strict_multiassignment_level == ERROR ? "extra_errors" :
  									   "extra_warnings"),
  							 errhint("Make sure the query returns the exact list of columns.")));
  			}
  
  			values = newvalues;
  			nulls = newnulls;
  		}
  
  		/* Insert the coerced field values into the new expanded record */
  		expanded_record_set_fields(newerh, values, nulls, !estate->atomic);
  
  		/* Complete the assignment */
  		assign_record_var(estate, rec, newerh);
  
  		return;
  	}
  
  	/* newerh should not have been passed in non-RECORD cases */
  	Assert(newerh == NULL);
  
  	/*
  	 * For a row, we assign the individual field values to the variables the
  	 * row points to.
  	 *
  	 * NOTE: both this code and the record code above silently ignore extra
  	 * columns in the source and assume NULL for missing columns.  This is
  	 * pretty dubious but it's the historical behavior.
  	 *
  	 * If we have no input data at all, we'll assign NULL to all columns of
  	 * the row variable.
  	 */
  	if (target->dtype == PLPGSQL_DTYPE_ROW)
  	{
  		PLpgSQL_row *row = (PLpgSQL_row *) target;
  
  		anum = 0;
  		for (fnum = 0; fnum < row->nfields; fnum++)
  		{
  			PLpgSQL_var *var;
  			Datum		value;
  			bool		isnull;
  			Oid			valtype;
  			int32		valtypmod;
  
  			var = (PLpgSQL_var *) (estate->datums[row->varnos[fnum]]);
  
  			while (anum < td_natts &&
  				   TupleDescAttr(tupdesc, anum)->attisdropped)
  				anum++;			/* skip dropped column in tuple */
  
  			if (anum < td_natts)
  			{
  				value = values[anum];
  				isnull = nulls[anum];
  				valtype = TupleDescAttr(tupdesc, anum)->atttypid;
  				valtypmod = TupleDescAttr(tupdesc, anum)->atttypmod;
  				anum++;
  			}
  			else
  			{
  				/* no source for destination column */
  				value = (Datum) 0;
  				isnull = true;
  				valtype = UNKNOWNOID;
  				valtypmod = -1;
  
  				if (strict_multiassignment_level)
  					ereport(strict_multiassignment_level,
  							(errcode(ERRCODE_DATATYPE_MISMATCH),
  							 errmsg("number of source and target fields in assignment does not match"),
  					/* translator: %s represents a name of an extra check */
  							 errdetail("%s check of %s is active.",
  									   "strict_multi_assignment",
  									   strict_multiassignment_level == ERROR ? "extra_errors" :
  									   "extra_warnings"),
  							 errhint("Make sure the query returns the exact list of columns.")));
  			}
  
  			exec_assign_value(estate, (PLpgSQL_datum *) var,
  							  value, isnull, valtype, valtypmod);
  		}
  
  		/*
  		 * When strict_multiassignment extra check is active, ensure there are
  		 * no unassigned source attributes.
  		 */
  		if (strict_multiassignment_level && anum < td_natts)
  		{
  			while (anum < td_natts &&
  				   TupleDescAttr(tupdesc, anum)->attisdropped)
  				anum++;			/* skip dropped column in tuple */
  
  			if (anum < td_natts)
  				ereport(strict_multiassignment_level,
  						(errcode(ERRCODE_DATATYPE_MISMATCH),
  						 errmsg("number of source and target fields in assignment does not match"),
  				/* translator: %s represents a name of an extra check */
  						 errdetail("%s check of %s is active.",
  								   "strict_multi_assignment",
  								   strict_multiassignment_level == ERROR ? "extra_errors" :
  								   "extra_warnings"),
  						 errhint("Make sure the query returns the exact list of columns.")));
  		}
  
  		return;
  	}
  
  	elog(ERROR, "unsupported target type: %d", target->dtype);
  }
  
  /*
   * compatible_tupdescs: detect whether two tupdescs are physically compatible
   *
   * TRUE indicates that a tuple satisfying src_tupdesc can be used directly as
   * a value for a composite variable using dst_tupdesc.
   */
  static bool
  compatible_tupdescs(TupleDesc src_tupdesc, TupleDesc dst_tupdesc)
  {
  	int			i;
  
  	/* Possibly we could allow src_tupdesc to have extra columns? */
  	if (dst_tupdesc->natts != src_tupdesc->natts)
  		return false;
  
  	for (i = 0; i < dst_tupdesc->natts; i++)
  	{
  		Form_pg_attribute dattr = TupleDescAttr(dst_tupdesc, i);
  		Form_pg_attribute sattr = TupleDescAttr(src_tupdesc, i);
  
  		if (dattr->attisdropped != sattr->attisdropped)
  			return false;
  		if (!dattr->attisdropped)
  		{
  			/* Normal columns must match by type and typmod */
  			if (dattr->atttypid != sattr->atttypid ||
  				(dattr->atttypmod >= 0 &&
  				 dattr->atttypmod != sattr->atttypmod))
  				return false;
  		}
  		else
  		{
  			/* Dropped columns are OK as long as length/alignment match */
  			if (dattr->attlen != sattr->attlen ||
  				dattr->attalign != sattr->attalign)
  				return false;
  		}
  	}
  	return true;
  }
  
  /* ----------
   * make_tuple_from_row		Make a tuple from the values of a row object
   *
   * A NULL return indicates rowtype mismatch; caller must raise suitable error
   *
   * The result tuple is freshly palloc'd in caller's context.  Some junk
   * may be left behind in eval_mcontext, too.
   * ----------
   */
  static HeapTuple
  make_tuple_from_row(PLpgSQL_execstate *estate,
  					PLpgSQL_row *row,
  					TupleDesc tupdesc)
  {
  	int			natts = tupdesc->natts;
  	HeapTuple	tuple;
  	Datum	   *dvalues;
  	bool	   *nulls;
  	int			i;
  
  	if (natts != row->nfields)
  		return NULL;
  
  	dvalues = (Datum *) eval_mcontext_alloc0(estate, natts * sizeof(Datum));
  	nulls = (bool *) eval_mcontext_alloc(estate, natts * sizeof(bool));
  
  	for (i = 0; i < natts; i++)
  	{
  		Oid			fieldtypeid;
  		int32		fieldtypmod;
  
  		if (TupleDescAttr(tupdesc, i)->attisdropped)
  		{
  			nulls[i] = true;	/* leave the column as null */
  			continue;
  		}
  
  		exec_eval_datum(estate, estate->datums[row->varnos[i]],
  						&fieldtypeid, &fieldtypmod,
  						&dvalues[i], &nulls[i]);
  		if (fieldtypeid != TupleDescAttr(tupdesc, i)->atttypid)
  			return NULL;
  		/* XXX should we insist on typmod match, too? */
  	}
  
  	tuple = heap_form_tuple(tupdesc, dvalues, nulls);
  
  	return tuple;
  }
  
  /*
   * deconstruct_composite_datum		extract tuple+tupdesc from composite Datum
   *
   * The caller must supply a HeapTupleData variable, in which we set up a
   * tuple header pointing to the composite datum's body.  To make the tuple
   * value outlive that variable, caller would need to apply heap_copytuple...
   * but current callers only need a short-lived tuple value anyway.
   *
   * Returns a pointer to the TupleDesc of the datum's rowtype.
   * Caller is responsible for calling ReleaseTupleDesc when done with it.
   *
   * Note: it's caller's responsibility to be sure value is of composite type.
   * Also, best to call this in a short-lived context, as it might leak memory.
   */
  static TupleDesc
  deconstruct_composite_datum(Datum value, HeapTupleData *tmptup)
  {
  	HeapTupleHeader td;
  	Oid			tupType;
  	int32		tupTypmod;
  
  	/* Get tuple body (note this could involve detoasting) */
  	td = DatumGetHeapTupleHeader(value);
  
  	/* Build a temporary HeapTuple control structure */
  	tmptup->t_len = HeapTupleHeaderGetDatumLength(td);
  	ItemPointerSetInvalid(&(tmptup->t_self));
  	tmptup->t_tableOid = InvalidOid;
  	tmptup->t_data = td;
  
  	/* Extract rowtype info and find a tupdesc */
  	tupType = HeapTupleHeaderGetTypeId(td);
  	tupTypmod = HeapTupleHeaderGetTypMod(td);
  	return lookup_rowtype_tupdesc(tupType, tupTypmod);
  }
  
  /*
   * exec_move_row_from_datum		Move a composite Datum into a record or row
   *
   * This is equivalent to deconstruct_composite_datum() followed by
   * exec_move_row(), but we can optimize things if the Datum is an
   * expanded-record reference.
   *
   * Note: it's caller's responsibility to be sure value is of composite type.
   */
  static void
  exec_move_row_from_datum(PLpgSQL_execstate *estate,
  						 PLpgSQL_variable *target,
  						 Datum value)
  {
  	/* Check to see if source is an expanded record */
  	if (VARATT_IS_EXTERNAL_EXPANDED(DatumGetPointer(value)))
  	{
  		ExpandedRecordHeader *erh = (ExpandedRecordHeader *) DatumGetEOHP(value);
  		ExpandedRecordHeader *newerh = NULL;
  
  		Assert(erh->er_magic == ER_MAGIC);
  
  		/* These cases apply if the target is record not row... */
  		if (target->dtype == PLPGSQL_DTYPE_REC)
  		{
  			PLpgSQL_rec *rec = (PLpgSQL_rec *) target;
  
  			/*
  			 * If it's the same record already stored in the variable, do
  			 * nothing.  This would happen only in silly cases like "r := r",
  			 * but we need some check to avoid possibly freeing the variable's
  			 * live value below.  Note that this applies even if what we have
  			 * is a R/O pointer.
  			 */
  			if (erh == rec->erh)
  				return;
  
  			/*
  			 * Make sure rec->rectypeid is up-to-date before using it.
  			 */
  			revalidate_rectypeid(rec);
  
  			/*
  			 * If we have a R/W pointer, we're allowed to just commandeer
  			 * ownership of the expanded record.  If it's of the right type to
  			 * put into the record variable, do that.  (Note we don't accept
  			 * an expanded record of a composite-domain type as a RECORD
  			 * value.  We'll treat it as the base composite type instead;
  			 * compare logic in make_expanded_record_for_rec.)
  			 */
  			if (VARATT_IS_EXTERNAL_EXPANDED_RW(DatumGetPointer(value)) &&
  				(rec->rectypeid == erh->er_decltypeid ||
  				 (rec->rectypeid == RECORDOID &&
  				  !ExpandedRecordIsDomain(erh))))
  			{
  				assign_record_var(estate, rec, erh);
  				return;
  			}
  
  			/*
  			 * If we already have an expanded record object in the target
  			 * variable, and the source record contains a valid tuple
  			 * representation with the right rowtype, then we can skip making
  			 * a new expanded record and just assign the tuple with
  			 * expanded_record_set_tuple.  (We can't do the equivalent if we
  			 * have to do field-by-field assignment, since that wouldn't be
  			 * atomic if there's an error.)  We consider that there's a
  			 * rowtype match only if it's the same named composite type or
  			 * same registered rowtype; checking for matches of anonymous
  			 * rowtypes would be more expensive than this is worth.
  			 */
  			if (rec->erh &&
  				(erh->flags & ER_FLAG_FVALUE_VALID) &&
  				erh->er_typeid == rec->erh->er_typeid &&
  				(erh->er_typeid != RECORDOID ||
  				 (erh->er_typmod == rec->erh->er_typmod &&
  				  erh->er_typmod >= 0)))
  			{
  				expanded_record_set_tuple(rec->erh, erh->fvalue,
  										  true, !estate->atomic);
  				return;
  			}
  
  			/*
  			 * Otherwise we're gonna need a new expanded record object.  Make
  			 * it here in hopes of piggybacking on the source object's
  			 * previous typcache lookup.
  			 */
  			newerh = make_expanded_record_for_rec(estate, rec, NULL, erh);
  
  			/*
  			 * If the expanded record contains a valid tuple representation,
  			 * and we don't need rowtype conversion, then just copying the
  			 * tuple is probably faster than field-by-field processing.  (This
  			 * isn't duplicative of the previous check, since here we will
  			 * catch the case where the record variable was previously empty.)
  			 */
  			if ((erh->flags & ER_FLAG_FVALUE_VALID) &&
  				(rec->rectypeid == RECORDOID ||
  				 rec->rectypeid == erh->er_typeid))
  			{
  				expanded_record_set_tuple(newerh, erh->fvalue,
  										  true, !estate->atomic);
  				assign_record_var(estate, rec, newerh);
  				return;
  			}
  
  			/*
  			 * Need to special-case empty source record, else code below would
  			 * leak newerh.
  			 */
  			if (ExpandedRecordIsEmpty(erh))
  			{
  				/* Set newerh to a row of NULLs */
  				deconstruct_expanded_record(newerh);
  				assign_record_var(estate, rec, newerh);
  				return;
  			}
  		}						/* end of record-target-only cases */
  
  		/*
  		 * If the source expanded record is empty, we should treat that like a
  		 * NULL tuple value.  (We're unlikely to see such a case, but we must
  		 * check this; deconstruct_expanded_record would cause a change of
  		 * logical state, which is not OK.)
  		 */
  		if (ExpandedRecordIsEmpty(erh))
  		{
  			exec_move_row(estate, target, NULL,
  						  expanded_record_get_tupdesc(erh));
  			return;
  		}
  
  		/*
  		 * Otherwise, ensure that the source record is deconstructed, and
  		 * assign from its field values.
  		 */
  		deconstruct_expanded_record(erh);
  		exec_move_row_from_fields(estate, target, newerh,
  								  erh->dvalues, erh->dnulls,
  								  expanded_record_get_tupdesc(erh));
  	}
  	else
  	{
  		/*
  		 * Nope, we've got a plain composite Datum.  Deconstruct it; but we
  		 * don't use deconstruct_composite_datum(), because we may be able to
  		 * skip calling lookup_rowtype_tupdesc().
  		 */
  		HeapTupleHeader td;
  		HeapTupleData tmptup;
  		Oid			tupType;
  		int32		tupTypmod;
  		TupleDesc	tupdesc;
  		MemoryContext oldcontext;
  
  		/* Ensure that any detoasted data winds up in the eval_mcontext */
  		oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate));
  		/* Get tuple body (note this could involve detoasting) */
  		td = DatumGetHeapTupleHeader(value);
  		MemoryContextSwitchTo(oldcontext);
  
  		/* Build a temporary HeapTuple control structure */
  		tmptup.t_len = HeapTupleHeaderGetDatumLength(td);
  		ItemPointerSetInvalid(&(tmptup.t_self));
  		tmptup.t_tableOid = InvalidOid;
  		tmptup.t_data = td;
  
  		/* Extract rowtype info */
  		tupType = HeapTupleHeaderGetTypeId(td);
  		tupTypmod = HeapTupleHeaderGetTypMod(td);
  
  		/* Now, if the target is record not row, maybe we can optimize ... */
  		if (target->dtype == PLPGSQL_DTYPE_REC)
  		{
  			PLpgSQL_rec *rec = (PLpgSQL_rec *) target;
  
  			/*
  			 * If we already have an expanded record object in the target
  			 * variable, and the source datum has a matching rowtype, then we
  			 * can skip making a new expanded record and just assign the tuple
  			 * with expanded_record_set_tuple.  We consider that there's a
  			 * rowtype match only if it's the same named composite type or
  			 * same registered rowtype.  (Checking to reject an anonymous
  			 * rowtype here should be redundant, but let's be safe.)
  			 */
  			if (rec->erh &&
  				tupType == rec->erh->er_typeid &&
  				(tupType != RECORDOID ||
  				 (tupTypmod == rec->erh->er_typmod &&
  				  tupTypmod >= 0)))
  			{
  				expanded_record_set_tuple(rec->erh, &tmptup,
  										  true, !estate->atomic);
  				return;
  			}
  
  			/*
  			 * If the source datum has a rowtype compatible with the target
  			 * variable, just build a new expanded record and assign the tuple
  			 * into it.  Using make_expanded_record_from_typeid() here saves
  			 * one typcache lookup compared to the code below.
  			 */
  			if (rec->rectypeid == RECORDOID || rec->rectypeid == tupType)
  			{
  				ExpandedRecordHeader *newerh;
  				MemoryContext mcontext = get_eval_mcontext(estate);
  
  				newerh = make_expanded_record_from_typeid(tupType, tupTypmod,
  														  mcontext);
  				expanded_record_set_tuple(newerh, &tmptup,
  										  true, !estate->atomic);
  				assign_record_var(estate, rec, newerh);
  				return;
  			}
  
  			/*
  			 * Otherwise, we're going to need conversion, so fall through to
  			 * do it the hard way.
  			 */
  		}
  
  		/*
  		 * ROW target, or unoptimizable RECORD target, so we have to expend a
  		 * lookup to obtain the source datum's tupdesc.
  		 */
  		tupdesc = lookup_rowtype_tupdesc(tupType, tupTypmod);
  
  		/* Do the move */
  		exec_move_row(estate, target, &tmptup, tupdesc);
  
  		/* Release tupdesc usage count */
  		ReleaseTupleDesc(tupdesc);
  	}
  }
  
  /*
   * If we have not created an expanded record to hold the record variable's
   * value, do so.  The expanded record will be "empty", so this does not
   * change the logical state of the record variable: it's still NULL.
   * However, now we'll have a tupdesc with which we can e.g. look up fields.
   */
  static void
  instantiate_empty_record_variable(PLpgSQL_execstate *estate, PLpgSQL_rec *rec)
  {
  	Assert(rec->erh == NULL);	/* else caller error */
  
  	/* If declared type is RECORD, we can't instantiate */
  	if (rec->rectypeid == RECORDOID)
  		ereport(ERROR,
  				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
  				 errmsg("record \"%s\" is not assigned yet", rec->refname),
  				 errdetail("The tuple structure of a not-yet-assigned record is indeterminate.")));
  
  	/* Make sure rec->rectypeid is up-to-date before using it */
  	revalidate_rectypeid(rec);
  
  	/* OK, do it */
  	rec->erh = make_expanded_record_from_typeid(rec->rectypeid, -1,
  												estate->datum_context);
  }
  
  /* ----------
   * convert_value_to_string			Convert a non-null Datum to C string
   *
   * Note: the result is in the estate's eval_mcontext, and will be cleared
   * by the next exec_eval_cleanup() call.  The invoked output function might
   * leave additional cruft there as well, so just pfree'ing the result string
   * would not be enough to avoid memory leaks if we did not do it like this.
   * In most usages the Datum being passed in is also in that context (if
   * pass-by-reference) and so an exec_eval_cleanup() call is needed anyway.
   *
   * Note: not caching the conversion function lookup is bad for performance.
   * However, this function isn't currently used in any places where an extra
   * catalog lookup or two seems like a big deal.
   * ----------
   */
  static char *
  convert_value_to_string(PLpgSQL_execstate *estate, Datum value, Oid valtype)
  {
  	char	   *result;
  	MemoryContext oldcontext;
  	Oid			typoutput;
  	bool		typIsVarlena;
  
  	oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate));
  	getTypeOutputInfo(valtype, &typoutput, &typIsVarlena);
  	result = OidOutputFunctionCall(typoutput, value);
  	MemoryContextSwitchTo(oldcontext);
  
  	return result;
  }
  
  /* ----------
   * exec_cast_value			Cast a value if required
   *
   * Note that *isnull is an input and also an output parameter.  While it's
   * unlikely that a cast operation would produce null from non-null or vice
   * versa, that could happen in principle.
   *
   * Note: the estate's eval_mcontext is used for temporary storage, and may
   * also contain the result Datum if we have to do a conversion to a pass-
   * by-reference data type.  Be sure to do an exec_eval_cleanup() call when
   * done with the result.
   * ----------
   */
  static Datum
  exec_cast_value(PLpgSQL_execstate *estate,
  				Datum value, bool *isnull,
  				Oid valtype, int32 valtypmod,
  				Oid reqtype, int32 reqtypmod)
  {
  	/*
  	 * If the type of the given value isn't what's requested, convert it.
  	 */
  	if (valtype != reqtype ||
  		(valtypmod != reqtypmod && reqtypmod != -1))
  	{
  		plpgsql_CastHashEntry *cast_entry;
  
  		cast_entry = get_cast_hashentry(estate,
  										valtype, valtypmod,
  										reqtype, reqtypmod);
  		if (cast_entry)
  		{
  			ExprContext *econtext = estate->eval_econtext;
  			MemoryContext oldcontext;
  
  			oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate));
  
  			econtext->caseValue_datum = value;
  			econtext->caseValue_isNull = *isnull;
  
  			cast_entry->cast_in_use = true;
  
  			value = ExecEvalExpr(cast_entry->cast_exprstate, econtext,
  								 isnull);
  
  			cast_entry->cast_in_use = false;
  
  			MemoryContextSwitchTo(oldcontext);
  		}
  	}
  
  	return value;
  }
  
  /* ----------
   * get_cast_hashentry			Look up how to perform a type cast
   *
   * Returns a plpgsql_CastHashEntry if an expression has to be evaluated,
   * or NULL if the cast is a mere no-op relabeling.  If there's work to be
   * done, the cast_exprstate field contains an expression evaluation tree
   * based on a CaseTestExpr input, and the cast_in_use field should be set
   * true while executing it.
   * ----------
   */
  static plpgsql_CastHashEntry *
  get_cast_hashentry(PLpgSQL_execstate *estate,
  				   Oid srctype, int32 srctypmod,
  				   Oid dsttype, int32 dsttypmod)
  {
  	plpgsql_CastHashKey cast_key;
  	plpgsql_CastHashEntry *cast_entry;
  	bool		found;
  	LocalTransactionId curlxid;
  	MemoryContext oldcontext;
  
  	/* Look for existing entry */
  	cast_key.srctype = srctype;
  	cast_key.dsttype = dsttype;
  	cast_key.srctypmod = srctypmod;
  	cast_key.dsttypmod = dsttypmod;
  	cast_entry = (plpgsql_CastHashEntry *) hash_search(estate->cast_hash,
  													   (void *) &cast_key,
  													   HASH_ENTER, &found);
  	if (!found)					/* initialize if new entry */
  		cast_entry->cast_cexpr = NULL;
  
  	if (cast_entry->cast_cexpr == NULL ||
  		!cast_entry->cast_cexpr->is_valid)
  	{
  		/*
  		 * We've not looked up this coercion before, or we have but the cached
  		 * expression has been invalidated.
  		 */
  		Node	   *cast_expr;
  		CachedExpression *cast_cexpr;
  		CaseTestExpr *placeholder;
  
  		/*
  		 * Drop old cached expression if there is one.
  		 */
  		if (cast_entry->cast_cexpr)
  		{
  			FreeCachedExpression(cast_entry->cast_cexpr);
  			cast_entry->cast_cexpr = NULL;
  		}
  
  		/*
  		 * Since we could easily fail (no such coercion), construct a
  		 * temporary coercion expression tree in the short-lived
  		 * eval_mcontext, then if successful save it as a CachedExpression.
  		 */
  		oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate));
  
  		/*
  		 * We use a CaseTestExpr as the base of the coercion tree, since it's
  		 * very cheap to insert the source value for that.
  		 */
  		placeholder = makeNode(CaseTestExpr);
  		placeholder->typeId = srctype;
  		placeholder->typeMod = srctypmod;
  		placeholder->collation = get_typcollation(srctype);
  
  		/*
  		 * Apply coercion.  We use ASSIGNMENT coercion because that's the
  		 * closest match to plpgsql's historical behavior; in particular,
  		 * EXPLICIT coercion would allow silent truncation to a destination
  		 * varchar/bpchar's length, which we do not want.
  		 *
  		 * If source type is UNKNOWN, coerce_to_target_type will fail (it only
  		 * expects to see that for Const input nodes), so don't call it; we'll
  		 * apply CoerceViaIO instead.  Likewise, it doesn't currently work for
  		 * coercing RECORD to some other type, so skip for that too.
  		 */
  		if (srctype == UNKNOWNOID || srctype == RECORDOID)
  			cast_expr = NULL;
  		else
  			cast_expr = coerce_to_target_type(NULL,
  											  (Node *) placeholder, srctype,
  											  dsttype, dsttypmod,
  											  COERCION_ASSIGNMENT,
  											  COERCE_IMPLICIT_CAST,
  											  -1);
  
  		/*
  		 * If there's no cast path according to the parser, fall back to using
  		 * an I/O coercion; this is semantically dubious but matches plpgsql's
  		 * historical behavior.  We would need something of the sort for
  		 * UNKNOWN literals in any case.
  		 */
  		if (cast_expr == NULL)
  		{
  			CoerceViaIO *iocoerce = makeNode(CoerceViaIO);
  
  			iocoerce->arg = (Expr *) placeholder;
  			iocoerce->resulttype = dsttype;
  			iocoerce->resultcollid = InvalidOid;
  			iocoerce->coerceformat = COERCE_IMPLICIT_CAST;
  			iocoerce->location = -1;
  			cast_expr = (Node *) iocoerce;
  			if (dsttypmod != -1)
  				cast_expr = coerce_to_target_type(NULL,
  												  cast_expr, dsttype,
  												  dsttype, dsttypmod,
  												  COERCION_ASSIGNMENT,
  												  COERCE_IMPLICIT_CAST,
  												  -1);
  		}
  
  		/* Note: we don't bother labeling the expression tree with collation */
  
  		/* Plan the expression and build a CachedExpression */
  		cast_cexpr = GetCachedExpression(cast_expr);
  		cast_expr = cast_cexpr->expr;
  
  		/* Detect whether we have a no-op (RelabelType) coercion */
  		if (IsA(cast_expr, RelabelType) &&
  			((RelabelType *) cast_expr)->arg == (Expr *) placeholder)
  			cast_expr = NULL;
  
  		/* Now we can fill in the hashtable entry. */
  		cast_entry->cast_cexpr = cast_cexpr;
  		cast_entry->cast_expr = (Expr *) cast_expr;
  		cast_entry->cast_exprstate = NULL;
  		cast_entry->cast_in_use = false;
  		cast_entry->cast_lxid = InvalidLocalTransactionId;
  
  		MemoryContextSwitchTo(oldcontext);
  	}
  
  	/* Done if we have determined that this is a no-op cast. */
  	if (cast_entry->cast_expr == NULL)
  		return NULL;
  
  	/*
  	 * Prepare the expression for execution, if it's not been done already in
  	 * the current transaction; also, if it's marked busy in the current
  	 * transaction, abandon that expression tree and build a new one, so as to
  	 * avoid potential problems with recursive cast expressions and failed
  	 * executions.  (We will leak some memory intra-transaction if that
  	 * happens a lot, but we don't expect it to.)  It's okay to update the
  	 * hash table with the new tree because all plpgsql functions within a
  	 * given transaction share the same simple_eval_estate.  (Well, regular
  	 * functions do; DO blocks have private simple_eval_estates, and private
  	 * cast hash tables to go with them.)
  	 */
  	curlxid = MyProc->lxid;
  	if (cast_entry->cast_lxid != curlxid || cast_entry->cast_in_use)
  	{
  		oldcontext = MemoryContextSwitchTo(estate->simple_eval_estate->es_query_cxt);
  		cast_entry->cast_exprstate = ExecInitExpr(cast_entry->cast_expr, NULL);
  		cast_entry->cast_in_use = false;
  		cast_entry->cast_lxid = curlxid;
  		MemoryContextSwitchTo(oldcontext);
  	}
  
  	return cast_entry;
  }
  
  
  /* ----------
   * exec_simple_check_plan -		Check if a plan is simple enough to
   *								be evaluated by ExecEvalExpr() instead
   *								of SPI.
   * ----------
   */
  static void
  exec_simple_check_plan(PLpgSQL_execstate *estate, PLpgSQL_expr *expr)
  {
  	List	   *plansources;
  	CachedPlanSource *plansource;
  	Query	   *query;
  	CachedPlan *cplan;
  	MemoryContext oldcontext;
  
  	/*
  	 * Initialize to "not simple".
  	 */
  	expr->expr_simple_expr = NULL;
  
  	/*
  	 * Check the analyzed-and-rewritten form of the query to see if we will be
  	 * able to treat it as a simple expression.  Since this function is only
  	 * called immediately after creating the CachedPlanSource, we need not
  	 * worry about the query being stale.
  	 */
  
  	/*
  	 * We can only test queries that resulted in exactly one CachedPlanSource
  	 */
  	plansources = SPI_plan_get_plan_sources(expr->plan);
  	if (list_length(plansources) != 1)
  		return;
  	plansource = (CachedPlanSource *) linitial(plansources);
  
  	/*
  	 * 1. There must be one single querytree.
  	 */
  	if (list_length(plansource->query_list) != 1)
  		return;
  	query = (Query *) linitial(plansource->query_list);
  
  	/*
  	 * 2. It must be a plain SELECT query without any input tables
  	 */
  	if (!IsA(query, Query))
  		return;
  	if (query->commandType != CMD_SELECT)
  		return;
  	if (query->rtable != NIL)
  		return;
  
  	/*
  	 * 3. Can't have any subplans, aggregates, qual clauses either.  (These
  	 * tests should generally match what inline_function() checks before
  	 * inlining a SQL function; otherwise, inlining could change our
  	 * conclusion about whether an expression is simple, which we don't want.)
  	 */
  	if (query->hasAggs ||
  		query->hasWindowFuncs ||
  		query->hasTargetSRFs ||
  		query->hasSubLinks ||
  		query->cteList ||
  		query->jointree->fromlist ||
  		query->jointree->quals ||
  		query->groupClause ||
  		query->groupingSets ||
  		query->havingQual ||
  		query->windowClause ||
  		query->distinctClause ||
  		query->sortClause ||
  		query->limitOffset ||
  		query->limitCount ||
  		query->setOperations)
  		return;
  
  	/*
  	 * 4. The query must have a single attribute as result
  	 */
  	if (list_length(query->targetList) != 1)
  		return;
  
  	/*
  	 * OK, we can treat it as a simple plan.
  	 *
  	 * Get the generic plan for the query.  If replanning is needed, do that
  	 * work in the eval_mcontext.
  	 */
  	oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate));
  	cplan = SPI_plan_get_cached_plan(expr->plan);
  	MemoryContextSwitchTo(oldcontext);
  
  	/* Can't fail, because we checked for a single CachedPlanSource above */
  	Assert(cplan != NULL);
  
  	/* Share the remaining work with replan code path */
  	exec_save_simple_expr(expr, cplan);
  
  	/* Release our plan refcount */
  	ReleaseCachedPlan(cplan, true);
  }
  
  /*
   * exec_save_simple_expr --- extract simple expression from CachedPlan
   */
  static void
  exec_save_simple_expr(PLpgSQL_expr *expr, CachedPlan *cplan)
  {
  	PlannedStmt *stmt;
  	Plan	   *plan;
  	Expr	   *tle_expr;
  
  	/*
  	 * Given the checks that exec_simple_check_plan did, none of the Asserts
  	 * here should ever fail.
  	 */
  
  	/* Extract the single PlannedStmt */
  	Assert(list_length(cplan->stmt_list) == 1);
  	stmt = linitial_node(PlannedStmt, cplan->stmt_list);
  	Assert(stmt->commandType == CMD_SELECT);
  
  	/*
  	 * Ordinarily, the plan node should be a simple Result.  However, if
  	 * force_parallel_mode is on, the planner might've stuck a Gather node
  	 * atop that.  The simplest way to deal with this is to look through the
  	 * Gather node.  The Gather node's tlist would normally contain a Var
  	 * referencing the child node's output, but it could also be a Param, or
  	 * it could be a Const that setrefs.c copied as-is.
  	 */
  	plan = stmt->planTree;
  	for (;;)
  	{
  		/* Extract the single tlist expression */
  		Assert(list_length(plan->targetlist) == 1);
  		tle_expr = castNode(TargetEntry, linitial(plan->targetlist))->expr;
  
  		if (IsA(plan, Result))
  		{
  			Assert(plan->lefttree == NULL &&
  				   plan->righttree == NULL &&
  				   plan->initPlan == NULL &&
  				   plan->qual == NULL &&
  				   ((Result *) plan)->resconstantqual == NULL);
  			break;
  		}
  		else if (IsA(plan, Gather))
  		{
  			Assert(plan->lefttree != NULL &&
  				   plan->righttree == NULL &&
  				   plan->initPlan == NULL &&
  				   plan->qual == NULL);
  			/* If setrefs.c copied up a Const, no need to look further */
  			if (IsA(tle_expr, Const))
  				break;
  			/* Otherwise, it had better be a Param or an outer Var */
  			Assert(IsA(tle_expr, Param) ||(IsA(tle_expr, Var) &&
  										   ((Var *) tle_expr)->varno == OUTER_VAR));
  			/* Descend to the child node */
  			plan = plan->lefttree;
  		}
  		else
  			elog(ERROR, "unexpected plan node type: %d",
  				 (int) nodeTag(plan));
  	}
  
  	/*
  	 * Save the simple expression, and initialize state to "not valid in
  	 * current transaction".
  	 */
  	expr->expr_simple_expr = tle_expr;
  	expr->expr_simple_generation = cplan->generation;
  	expr->expr_simple_state = NULL;
  	expr->expr_simple_in_use = false;
  	expr->expr_simple_lxid = InvalidLocalTransactionId;
  	/* Also stash away the expression result type */
  	expr->expr_simple_type = exprType((Node *) tle_expr);
  	expr->expr_simple_typmod = exprTypmod((Node *) tle_expr);
  	/* We also want to remember if it is immutable or not */
  	expr->expr_simple_mutable = contain_mutable_functions((Node *) tle_expr);
  }
  
  /*
   * exec_check_rw_parameter --- can we pass expanded object as read/write param?
   *
   * If we have an assignment like "x := array_append(x, foo)" in which the
   * top-level function is trusted not to corrupt its argument in case of an
   * error, then when x has an expanded object as value, it is safe to pass the
   * value as a read/write pointer and let the function modify the value
   * in-place.
   *
   * This function checks for a safe expression, and sets expr->rwparam to the
   * dno of the target variable (x) if safe, or -1 if not safe.
   */
  static void
  exec_check_rw_parameter(PLpgSQL_expr *expr, int target_dno)
  {
  	Oid			funcid;
  	List	   *fargs;
  	ListCell   *lc;
  
  	/* Assume unsafe */
  	expr->rwparam = -1;
  
  	/*
  	 * If the expression isn't simple, there's no point in trying to optimize
  	 * (because the exec_run_select code path will flatten any expanded result
  	 * anyway).  Even without that, this seems like a good safety restriction.
  	 */
  	if (expr->expr_simple_expr == NULL)
  		return;
  
  	/*
  	 * If target variable isn't referenced by expression, no need to look
  	 * further.
  	 */
  	if (!bms_is_member(target_dno, expr->paramnos))
  		return;
  
  	/*
  	 * Top level of expression must be a simple FuncExpr or OpExpr.
  	 */
  	if (IsA(expr->expr_simple_expr, FuncExpr))
  	{
  		FuncExpr   *fexpr = (FuncExpr *) expr->expr_simple_expr;
  
  		funcid = fexpr->funcid;
  		fargs = fexpr->args;
  	}
  	else if (IsA(expr->expr_simple_expr, OpExpr))
  	{
  		OpExpr	   *opexpr = (OpExpr *) expr->expr_simple_expr;
  
  		funcid = opexpr->opfuncid;
  		fargs = opexpr->args;
  	}
  	else
  		return;
  
  	/*
  	 * The top-level function must be one that we trust to be "safe".
  	 * Currently we hard-wire the list, but it would be very desirable to
  	 * allow extensions to mark their functions as safe ...
  	 */
  	if (!(funcid == F_ARRAY_APPEND ||
  		  funcid == F_ARRAY_PREPEND))
  		return;
  
  	/*
  	 * The target variable (in the form of a Param) must only appear as a
  	 * direct argument of the top-level function.
  	 */
  	foreach(lc, fargs)
  	{
  		Node	   *arg = (Node *) lfirst(lc);
  
  		/* A Param is OK, whether it's the target variable or not */
  		if (arg && IsA(arg, Param))
  			continue;
  		/* Otherwise, argument expression must not reference target */
  		if (contains_target_param(arg, &target_dno))
  			return;
  	}
  
  	/* OK, we can pass target as a read-write parameter */
  	expr->rwparam = target_dno;
  }
  
  /*
   * Recursively check for a Param referencing the target variable
   */
  static bool
  contains_target_param(Node *node, int *target_dno)
  {
  	if (node == NULL)
  		return false;
  	if (IsA(node, Param))
  	{
  		Param	   *param = (Param *) node;
  
  		if (param->paramkind == PARAM_EXTERN &&
  			param->paramid == *target_dno + 1)
  			return true;
  		return false;
  	}
  	return expression_tree_walker(node, contains_target_param,
  								  (void *) target_dno);
  }
  
  /* ----------
   * exec_set_found			Set the global found variable to true/false
   * ----------
   */
  static void
  exec_set_found(PLpgSQL_execstate *estate, bool state)
  {
  	PLpgSQL_var *var;
  
  	var = (PLpgSQL_var *) (estate->datums[estate->found_varno]);
  	assign_simple_var(estate, var, BoolGetDatum(state), false, false);
  }
  
  /*
   * plpgsql_create_econtext --- create an eval_econtext for the current function
   *
   * We may need to create a new shared_simple_eval_estate too, if there's not
   * one already for the current transaction.  The EState will be cleaned up at
   * transaction end.
   */
  static void
  plpgsql_create_econtext(PLpgSQL_execstate *estate)
  {
  	SimpleEcontextStackEntry *entry;
  
  	/*
  	 * Create an EState for evaluation of simple expressions, if there's not
  	 * one already in the current transaction.  The EState is made a child of
  	 * TopTransactionContext so it will have the right lifespan.
  	 *
  	 * Note that this path is never taken when executing a DO block; the
  	 * required EState was already made by plpgsql_inline_handler.
  	 */
  	if (estate->simple_eval_estate == NULL)
  	{
  		MemoryContext oldcontext;
  
  		if (shared_simple_eval_estate == NULL)
  		{
  			oldcontext = MemoryContextSwitchTo(TopTransactionContext);
  			shared_simple_eval_estate = CreateExecutorState();
  			MemoryContextSwitchTo(oldcontext);
  		}
  		estate->simple_eval_estate = shared_simple_eval_estate;
  	}
  
  	/*
  	 * Create a child econtext for the current function.
  	 */
  	estate->eval_econtext = CreateExprContext(estate->simple_eval_estate);
  
  	/*
  	 * Make a stack entry so we can clean up the econtext at subxact end.
  	 * Stack entries are kept in TopTransactionContext for simplicity.
  	 */
  	entry = (SimpleEcontextStackEntry *)
  		MemoryContextAlloc(TopTransactionContext,
  						   sizeof(SimpleEcontextStackEntry));
  
  	entry->stack_econtext = estate->eval_econtext;
  	entry->xact_subxid = GetCurrentSubTransactionId();
  
  	entry->next = simple_econtext_stack;
  	simple_econtext_stack = entry;
  }
  
  /*
   * plpgsql_destroy_econtext --- destroy function's econtext
   *
   * We check that it matches the top stack entry, and destroy the stack
   * entry along with the context.
   */
  static void
  plpgsql_destroy_econtext(PLpgSQL_execstate *estate)
  {
  	SimpleEcontextStackEntry *next;
  
  	Assert(simple_econtext_stack != NULL);
  	Assert(simple_econtext_stack->stack_econtext == estate->eval_econtext);
  
  	next = simple_econtext_stack->next;
  	pfree(simple_econtext_stack);
  	simple_econtext_stack = next;
  
  	FreeExprContext(estate->eval_econtext, true);
  	estate->eval_econtext = NULL;
  }
  
  /*
   * plpgsql_xact_cb --- post-transaction-commit-or-abort cleanup
   *
   * If a simple-expression EState was created in the current transaction,
   * it has to be cleaned up.
   */
  void
  plpgsql_xact_cb(XactEvent event, void *arg)
  {
  	/*
  	 * If we are doing a clean transaction shutdown, free the EState (so that
  	 * any remaining resources will be released correctly). In an abort, we
  	 * expect the regular abort recovery procedures to release everything of
  	 * interest.
  	 */
  	if (event == XACT_EVENT_COMMIT || event == XACT_EVENT_PREPARE)
  	{
  		simple_econtext_stack = NULL;
  
  		if (shared_simple_eval_estate)
  			FreeExecutorState(shared_simple_eval_estate);
  		shared_simple_eval_estate = NULL;
  	}
  	else if (event == XACT_EVENT_ABORT)
  	{
  		simple_econtext_stack = NULL;
  		shared_simple_eval_estate = NULL;
  	}
  }
  
  /*
   * plpgsql_subxact_cb --- post-subtransaction-commit-or-abort cleanup
   *
   * Make sure any simple-expression econtexts created in the current
   * subtransaction get cleaned up.  We have to do this explicitly because
   * no other code knows which econtexts belong to which level of subxact.
   */
  void
  plpgsql_subxact_cb(SubXactEvent event, SubTransactionId mySubid,
  				   SubTransactionId parentSubid, void *arg)
  {
  	if (event == SUBXACT_EVENT_COMMIT_SUB || event == SUBXACT_EVENT_ABORT_SUB)
  	{
  		while (simple_econtext_stack != NULL &&
  			   simple_econtext_stack->xact_subxid == mySubid)
  		{
  			SimpleEcontextStackEntry *next;
  
  			FreeExprContext(simple_econtext_stack->stack_econtext,
  							(event == SUBXACT_EVENT_COMMIT_SUB));
  			next = simple_econtext_stack->next;
  			pfree(simple_econtext_stack);
  			simple_econtext_stack = next;
  		}
  	}
  }
  
  /*
   * assign_simple_var --- assign a new value to any VAR datum.
   *
   * This should be the only mechanism for assignment to simple variables,
   * lest we do the release of the old value incorrectly (not to mention
   * the detoasting business).
   */
  static void
  assign_simple_var(PLpgSQL_execstate *estate, PLpgSQL_var *var,
  				  Datum newvalue, bool isnull, bool freeable)
  {
  	Assert(var->dtype == PLPGSQL_DTYPE_VAR ||
  		   var->dtype == PLPGSQL_DTYPE_PROMISE);
  
  	/*
  	 * In non-atomic contexts, we do not want to store TOAST pointers in
  	 * variables, because such pointers might become stale after a commit.
  	 * Forcibly detoast in such cases.  We don't want to detoast (flatten)
  	 * expanded objects, however; those should be OK across a transaction
  	 * boundary since they're just memory-resident objects.  (Elsewhere in
  	 * this module, operations on expanded records likewise need to request
  	 * detoasting of record fields when !estate->atomic.  Expanded arrays are
  	 * not a problem since all array entries are always detoasted.)
  	 */
  	if (!estate->atomic && !isnull && var->datatype->typlen == -1 &&
  		VARATT_IS_EXTERNAL_NON_EXPANDED(DatumGetPointer(newvalue)))
  	{
  		MemoryContext oldcxt;
  		Datum		detoasted;
  
  		/*
  		 * Do the detoasting in the eval_mcontext to avoid long-term leakage
  		 * of whatever memory toast fetching might leak.  Then we have to copy
  		 * the detoasted datum to the function's main context, which is a
  		 * pain, but there's little choice.
  		 */
  		oldcxt = MemoryContextSwitchTo(get_eval_mcontext(estate));
  		detoasted = PointerGetDatum(detoast_external_attr((struct varlena *) DatumGetPointer(newvalue)));
  		MemoryContextSwitchTo(oldcxt);
  		/* Now's a good time to not leak the input value if it's freeable */
  		if (freeable)
  			pfree(DatumGetPointer(newvalue));
  		/* Once we copy the value, it's definitely freeable */
  		newvalue = datumCopy(detoasted, false, -1);
  		freeable = true;
  		/* Can't clean up eval_mcontext here, but it'll happen before long */
  	}
  
  	/* Free the old value if needed */
  	if (var->freeval)
  	{
  		if (DatumIsReadWriteExpandedObject(var->value,
  										   var->isnull,
  										   var->datatype->typlen))
  			DeleteExpandedObject(var->value);
  		else
  			pfree(DatumGetPointer(var->value));
  	}
  	/* Assign new value to datum */
  	var->value = newvalue;
  	var->isnull = isnull;
  	var->freeval = freeable;
  
  	/*
  	 * If it's a promise variable, then either we just assigned the promised
  	 * value, or the user explicitly assigned an overriding value.  Either
  	 * way, cancel the promise.
  	 */
  	var->promise = PLPGSQL_PROMISE_NONE;
  }
  
  /*
   * free old value of a text variable and assign new value from C string
   */
  static void
  assign_text_var(PLpgSQL_execstate *estate, PLpgSQL_var *var, const char *str)
  {
  	assign_simple_var(estate, var, CStringGetTextDatum(str), false, true);
  }
  
  /*
   * assign_record_var --- assign a new value to any REC datum.
   */
  static void
  assign_record_var(PLpgSQL_execstate *estate, PLpgSQL_rec *rec,
  				  ExpandedRecordHeader *erh)
  {
  	Assert(rec->dtype == PLPGSQL_DTYPE_REC);
  
  	/* Transfer new record object into datum_context */
  	TransferExpandedRecord(erh, estate->datum_context);
  
  	/* Free the old value ... */
  	if (rec->erh)
  		DeleteExpandedObject(ExpandedRecordGetDatum(rec->erh));
  
  	/* ... and install the new */
  	rec->erh = erh;
  }
  
  /*
   * exec_eval_using_params --- evaluate params of USING clause
   *
   * The result data structure is created in the stmt_mcontext, and should
   * be freed by resetting that context.
   */
  static PreparedParamsData *
  exec_eval_using_params(PLpgSQL_execstate *estate, List *params)
  {
  	PreparedParamsData *ppd;
  	MemoryContext stmt_mcontext = get_stmt_mcontext(estate);
  	int			nargs;
  	int			i;
  	ListCell   *lc;
  
  	ppd = (PreparedParamsData *)
  		MemoryContextAlloc(stmt_mcontext, sizeof(PreparedParamsData));
  	nargs = list_length(params);
  
  	ppd->nargs = nargs;
  	ppd->types = (Oid *)
  		MemoryContextAlloc(stmt_mcontext, nargs * sizeof(Oid));
  	ppd->values = (Datum *)
  		MemoryContextAlloc(stmt_mcontext, nargs * sizeof(Datum));
  	ppd->nulls = (char *)
  		MemoryContextAlloc(stmt_mcontext, nargs * sizeof(char));
  
  	i = 0;
  	foreach(lc, params)
  	{
  		PLpgSQL_expr *param = (PLpgSQL_expr *) lfirst(lc);
  		bool		isnull;
  		int32		ppdtypmod;
  		MemoryContext oldcontext;
  
  		ppd->values[i] = exec_eval_expr(estate, param,
  										&isnull,
  										&ppd->types[i],
  										&ppdtypmod);
  		ppd->nulls[i] = isnull ? 'n' : ' ';
  
  		oldcontext = MemoryContextSwitchTo(stmt_mcontext);
  
  		if (ppd->types[i] == UNKNOWNOID)
  		{
  			/*
  			 * Treat 'unknown' parameters as text, since that's what most
  			 * people would expect. SPI_execute_with_args can coerce unknown
  			 * constants in a more intelligent way, but not unknown Params.
  			 * This code also takes care of copying into the right context.
  			 * Note we assume 'unknown' has the representation of C-string.
  			 */
  			ppd->types[i] = TEXTOID;
  			if (!isnull)
  				ppd->values[i] = CStringGetTextDatum(DatumGetCString(ppd->values[i]));
  		}
  		/* pass-by-ref non null values must be copied into stmt_mcontext */
  		else if (!isnull)
  		{
  			int16		typLen;
  			bool		typByVal;
  
  			get_typlenbyval(ppd->types[i], &typLen, &typByVal);
  			if (!typByVal)
  				ppd->values[i] = datumCopy(ppd->values[i], typByVal, typLen);
  		}
  
  		MemoryContextSwitchTo(oldcontext);
  
  		exec_eval_cleanup(estate);
  
  		i++;
  	}
  
  	return ppd;
  }
  
  /*
   * Open portal for dynamic query
   *
   * Caution: this resets the stmt_mcontext at exit.  We might eventually need
   * to move that responsibility to the callers, but currently no caller needs
   * to have statement-lifetime temp data that survives past this, so it's
   * simpler to do it here.
   */
  static Portal
  exec_dynquery_with_params(PLpgSQL_execstate *estate,
  						  PLpgSQL_expr *dynquery,
  						  List *params,
  						  const char *portalname,
  						  int cursorOptions)
  {
  	Portal		portal;
  	Datum		query;
  	bool		isnull;
  	Oid			restype;
  	int32		restypmod;
  	char	   *querystr;
  	MemoryContext stmt_mcontext = get_stmt_mcontext(estate);
  
  	/*
  	 * Evaluate the string expression after the EXECUTE keyword. Its result is
  	 * the querystring we have to execute.
  	 */
  	query = exec_eval_expr(estate, dynquery, &isnull, &restype, &restypmod);
  	if (isnull)
  		ereport(ERROR,
  				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
  				 errmsg("query string argument of EXECUTE is null")));
  
  	/* Get the C-String representation */
  	querystr = convert_value_to_string(estate, query, restype);
  
  	/* copy it into the stmt_mcontext before we clean up */
  	querystr = MemoryContextStrdup(stmt_mcontext, querystr);
  
  	exec_eval_cleanup(estate);
  
  	/*
  	 * Open an implicit cursor for the query.  We use
  	 * SPI_cursor_open_with_args even when there are no params, because this
  	 * avoids making and freeing one copy of the plan.
  	 */
  	if (params)
  	{
  		PreparedParamsData *ppd;
  
  		ppd = exec_eval_using_params(estate, params);
  		portal = SPI_cursor_open_with_args(portalname,
  										   querystr,
  										   ppd->nargs, ppd->types,
  										   ppd->values, ppd->nulls,
  										   estate->readonly_func,
  										   cursorOptions);
  	}
  	else
  	{
  		portal = SPI_cursor_open_with_args(portalname,
  										   querystr,
  										   0, NULL,
  										   NULL, NULL,
  										   estate->readonly_func,
  										   cursorOptions);
  	}
  
  	if (portal == NULL)
  		elog(ERROR, "could not open implicit cursor for query \"%s\": %s",
  			 querystr, SPI_result_code_string(SPI_result));
  
  	/* Release transient data */
  	MemoryContextReset(stmt_mcontext);
  
  	return portal;
  }
  
  /*
   * Return a formatted string with information about an expression's parameters,
   * or NULL if the expression does not take any parameters.
   * The result is in the eval_mcontext.
   */
  static char *
  format_expr_params(PLpgSQL_execstate *estate,
  				   const PLpgSQL_expr *expr)
  {
  	int			paramno;
  	int			dno;
  	StringInfoData paramstr;
  	MemoryContext oldcontext;
  
  	if (!expr->paramnos)
  		return NULL;
  
  	oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate));
  
  	initStringInfo(&paramstr);
  	paramno = 0;
  	dno = -1;
  	while ((dno = bms_next_member(expr->paramnos, dno)) >= 0)
  	{
  		Datum		paramdatum;
  		Oid			paramtypeid;
  		bool		paramisnull;
  		int32		paramtypmod;
  		PLpgSQL_var *curvar;
  
  		curvar = (PLpgSQL_var *) estate->datums[dno];
  
  		exec_eval_datum(estate, (PLpgSQL_datum *) curvar,
  						&paramtypeid, &paramtypmod,
  						&paramdatum, &paramisnull);
  
  		appendStringInfo(&paramstr, "%s%s = ",
  						 paramno > 0 ? ", " : "",
  						 curvar->refname);
  
  		if (paramisnull)
  			appendStringInfoString(&paramstr, "NULL");
  		else
  			appendStringInfoStringQuoted(&paramstr,
  										 convert_value_to_string(estate,
  																 paramdatum,
  																 paramtypeid),
  										 0);
  
  		paramno++;
  	}
  
  	MemoryContextSwitchTo(oldcontext);
  
  	return paramstr.data;
  }
  
  /*
   * Return a formatted string with information about PreparedParamsData, or NULL
   * if there are no parameters.
   * The result is in the eval_mcontext.
   */
  static char *
  format_preparedparamsdata(PLpgSQL_execstate *estate,
  						  const PreparedParamsData *ppd)
  {
  	int			paramno;
  	StringInfoData paramstr;
  	MemoryContext oldcontext;
  
  	if (!ppd)
  		return NULL;
  
  	oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate));
  
  	initStringInfo(&paramstr);
  	for (paramno = 0; paramno < ppd->nargs; paramno++)
  	{
  		appendStringInfo(&paramstr, "%s$%d = ",
  						 paramno > 0 ? ", " : "",
  						 paramno + 1);
  
  		if (ppd->nulls[paramno] == 'n')
  			appendStringInfoString(&paramstr, "NULL");
  		else
  			appendStringInfoStringQuoted(&paramstr,
  										 convert_value_to_string(estate,
  																 ppd->values[paramno],
  																 ppd->types[paramno]),
  										 0);
  	}
  
  	MemoryContextSwitchTo(oldcontext);
  
  	return paramstr.data;
  }
  