text: /*-------------------------------------------------------------------------
   *
   * pl_exec.c		- Executor for the PL/pgSQL
   *			  procedural language
   *
   * Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   *
   * IDENTIFICATION
   *	  src/pl/plpgsql/src/pl_exec.c
   *
   *-------------------------------------------------------------------------
   */
  
  #include "plpgsql.h"
  
  #include <ctype.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 "executor/spi.h"
  #include "funcapi.h"
  #include "miscadmin.h"
  #include "nodes/nodeFuncs.h"
  #include "parser/scansup.h"
  #include "storage/proc.h"
  #include "tcop/tcopprot.h"
  #include "utils/array.h"
  #include "utils/builtins.h"
  #include "utils/datum.h"
  #include "utils/lsyscache.h"
  #include "utils/memutils.h"
  #include "utils/rel.h"
  #include "utils/snapmgr.h"
  #include "utils/typcache.h"
  
  
  static const char *const raise_skip_msg = "RAISE";
  
  typedef struct
  {
  	int			nargs;			/* number of arguments */
  	Oid		   *types;			/* types of arguments */
  	Datum	   *values;			/* evaluated argument values */
  	char	   *nulls;			/* null markers (' '/'n' style) */
  	bool	   *freevals;		/* which arguments are pfree-able */
  } 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;
  
  /************************************************************
   * Local function forward declarations
   ************************************************************/
  static void plpgsql_exec_error_callback(void *arg);
  static PLpgSQL_datum *copy_plpgsql_datum(PLpgSQL_datum *datum);
  
  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_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_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 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);
  static bool exec_simple_check_node(Node *node);
  static void exec_simple_check_plan(PLpgSQL_expr *expr);
  static void exec_simple_recheck_plan(PLpgSQL_expr *expr, CachedPlan *cplan);
  static bool exec_eval_simple_expr(PLpgSQL_execstate *estate,
  					  PLpgSQL_expr *expr,
  					  Datum *result,
  					  bool *isNull,
  					  Oid *rettype);
  
  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, Oid valtype, bool *isNull);
  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);
  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 void plpgsql_param_fetch(ParamListInfo params, int paramid);
  static void exec_move_row(PLpgSQL_execstate *estate,
  			  PLpgSQL_rec *rec,
  			  PLpgSQL_row *row,
  			  HeapTuple tup, TupleDesc tupdesc);
  static HeapTuple make_tuple_from_row(PLpgSQL_execstate *estate,
  					PLpgSQL_row *row,
  					TupleDesc tupdesc);
  static HeapTuple get_tuple_from_datum(Datum value);
  static TupleDesc get_tupdesc_from_datum(Datum value);
  static void exec_move_row_from_datum(PLpgSQL_execstate *estate,
  						 PLpgSQL_rec *rec,
  						 PLpgSQL_row *row,
  						 Datum value);
  static char *convert_value_to_string(PLpgSQL_execstate *estate,
  						Datum value, Oid valtype);
  static Datum exec_cast_value(PLpgSQL_execstate *estate,
  				Datum value, Oid valtype,
  				Oid reqtype,
  				FmgrInfo *reqinput,
  				Oid reqtypioparam,
  				int32 reqtypmod,
  				bool isnull);
  static Datum exec_simple_cast_value(PLpgSQL_execstate *estate,
  					   Datum value, Oid valtype,
  					   Oid reqtype, int32 reqtypmod,
  					   bool isnull);
  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 free_var(PLpgSQL_var *var);
  static void assign_text_var(PLpgSQL_var *var, const char *str);
  static PreparedParamsData *exec_eval_using_params(PLpgSQL_execstate *estate,
  					   List *params);
  static void free_params_data(PreparedParamsData *ppd);
  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.
   * ----------
   */
  Datum
  plpgsql_exec_function(PLpgSQL_function *func, FunctionCallInfo fcinfo,
  					  EState *simple_eval_estate)
  {
  	PLpgSQL_execstate estate;
  	ErrorContextCallback plerrcontext;
  	int			i;
  	int			rc;
  
  	/*
  	 * Setup the execution state
  	 */
  	plpgsql_estate_setup(&estate, func, (ReturnSetInfo *) fcinfo->resultinfo,
  						 simple_eval_estate);
  
  	/*
  	 * 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");
  	for (i = 0; i < estate.ndatums; i++)
  		estate.datums[i] = copy_plpgsql_datum(func->datums[i]);
  
  	/*
  	 * 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];
  
  					var->value = fcinfo->arg[i];
  					var->isnull = fcinfo->argnull[i];
  					var->freeval = false;
  				}
  				break;
  
  			case PLPGSQL_DTYPE_ROW:
  				{
  					PLpgSQL_row *row = (PLpgSQL_row *) estate.datums[n];
  
  					if (!fcinfo->argnull[i])
  					{
  						/* Assign row value from composite datum */
  						exec_move_row_from_datum(&estate, NULL, row,
  												 fcinfo->arg[i]);
  					}
  					else
  					{
  						/* If arg is null, treat it as an empty row */
  						exec_move_row(&estate, NULL, row, NULL, NULL);
  					}
  					/* clean up after exec_move_row() */
  					exec_eval_cleanup(&estate);
  				}
  				break;
  
  			default:
  				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 (*plugin_ptr && (*plugin_ptr)->func_beg)
  		((*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_block(&estate, func->action);
  	if (rc != PLPGSQL_RC_RETURN)
  	{
  		estate.err_stmt = NULL;
  		estate.err_text = NULL;
  
  		/*
  		 * Provide a more helpful message if a CONTINUE or RAISE has been used
  		 * outside the context it can work in.
  		 */
  		if (rc == PLPGSQL_RC_CONTINUE)
  			ereport(ERROR,
  					(errcode(ERRCODE_SYNTAX_ERROR),
  					 errmsg("CONTINUE cannot be used outside a loop")));
  		else
  			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)
  		{
  			rsi->setResult = estate.tuple_store;
  			if (estate.rettupdesc)
  			{
  				MemoryContext oldcxt;
  
  				oldcxt = MemoryContextSwitchTo(estate.tuple_store_cxt);
  				rsi->setDesc = CreateTupleDescCopy(estate.rettupdesc);
  				MemoryContextSwitchTo(oldcxt);
  			}
  		}
  		estate.retval = (Datum) 0;
  		fcinfo->isnull = true;
  	}
  	else if (!estate.retisnull)
  	{
  		if (estate.retistuple)
  		{
  			/*
  			 * We have to check that the returned tuple actually matches the
  			 * expected result type.  XXX would be better to cache the tupdesc
  			 * instead of repeating get_call_result_type()
  			 */
  			HeapTuple	rettup = (HeapTuple) DatumGetPointer(estate.retval);
  			TupleDesc	tupdesc;
  			TupleConversionMap *tupmap;
  
  			switch (get_call_result_type(fcinfo, NULL, &tupdesc))
  			{
  				case TYPEFUNC_COMPOSITE:
  					/* got the expected result rowtype, now check it */
  					tupmap = convert_tuples_by_position(estate.rettupdesc,
  														tupdesc,
  														gettext_noop("returned record type does not match expected record type"));
  					/* it might need conversion */
  					if (tupmap)
  						rettup = do_convert_tuple(rettup, tupmap);
  					/* no need to free map, we're about to return anyway */
  					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 type, instead.
  					 */
  					tupdesc = estate.rettupdesc;
  					if (tupdesc == NULL)		/* shouldn't happen */
  						elog(ERROR, "return type must be a row type");
  					break;
  				default:
  					/* shouldn't get here if retistuple is true ... */
  					elog(ERROR, "return type must be a row type");
  					break;
  			}
  
  			/*
  			 * 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));
  		}
  		else
  		{
  			/* Cast value to proper type */
  			estate.retval = exec_cast_value(&estate,
  											estate.retval,
  											estate.rettype,
  											func->fn_rettype,
  											&(func->fn_retinput),
  											func->fn_rettypioparam,
  											-1,
  											fcinfo->isnull);
  
  			/*
  			 * If the function's return type isn't by value, copy the value
  			 * into upper executor memory context.
  			 */
  			if (!fcinfo->isnull && !func->fn_retbyval)
  			{
  				Size		len;
  				void	   *tmp;
  
  				len = datumGetSize(estate.retval, false, func->fn_rettyplen);
  				tmp = SPI_palloc(len);
  				memcpy(tmp, DatumGetPointer(estate.retval), len);
  				estate.retval = PointerGetDatum(tmp);
  			}
  		}
  	}
  
  	estate.err_text = gettext_noop("during function exit");
  
  	/*
  	 * Let the instrumentation plugin peek at this function
  	 */
  	if (*plugin_ptr && (*plugin_ptr)->func_end)
  		((*plugin_ptr)->func_end) (&estate, func);
  
  	/* Clean up any leftover temporary memory */
  	plpgsql_destroy_econtext(&estate);
  	exec_eval_cleanup(&estate);
  
  	/*
  	 * Pop the error context stack
  	 */
  	error_context_stack = plerrcontext.previous;
  
  	/*
  	 * Return the function's result
  	 */
  	return estate.retval;
  }
  
  
  /* ----------
   * 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			i;
  	int			rc;
  	PLpgSQL_var *var;
  	PLpgSQL_rec *rec_new,
  			   *rec_old;
  	HeapTuple	rettup;
  
  	/*
  	 * Setup the execution state
  	 */
  	plpgsql_estate_setup(&estate, func, NULL, NULL);
  
  	/*
  	 * 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");
  	for (i = 0; i < estate.ndatums; i++)
  		estate.datums[i] = copy_plpgsql_datum(func->datums[i]);
  
  	/*
  	 * Put the OLD and NEW tuples into record variables
  	 *
  	 * We make the tupdescs available in both records even though only one may
  	 * have a value.  This allows parsing of 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 parse regardless of the current trigger type.
  	 */
  	rec_new = (PLpgSQL_rec *) (estate.datums[func->new_varno]);
  	rec_new->freetup = false;
  	rec_new->tupdesc = trigdata->tg_relation->rd_att;
  	rec_new->freetupdesc = false;
  	rec_old = (PLpgSQL_rec *) (estate.datums[func->old_varno]);
  	rec_old->freetup = false;
  	rec_old->tupdesc = trigdata->tg_relation->rd_att;
  	rec_old->freetupdesc = false;
  
  	if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
  	{
  		/*
  		 * Per-statement triggers don't use OLD/NEW variables
  		 */
  		rec_new->tup = NULL;
  		rec_old->tup = NULL;
  	}
  	else if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
  	{
  		rec_new->tup = trigdata->tg_trigtuple;
  		rec_old->tup = NULL;
  	}
  	else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
  	{
  		rec_new->tup = trigdata->tg_newtuple;
  		rec_old->tup = trigdata->tg_trigtuple;
  	}
  	else if (TRIGGER_FIRED_BY_DELETE(trigdata->tg_event))
  	{
  		rec_new->tup = NULL;
  		rec_old->tup = trigdata->tg_trigtuple;
  	}
  	else
  		elog(ERROR, "unrecognized trigger action: not INSERT, DELETE, or UPDATE");
  
  	/*
  	 * Assign the special tg_ variables
  	 */
  
  	var = (PLpgSQL_var *) (estate.datums[func->tg_op_varno]);
  	if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
  		var->value = CStringGetTextDatum("INSERT");
  	else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
  		var->value = CStringGetTextDatum("UPDATE");
  	else if (TRIGGER_FIRED_BY_DELETE(trigdata->tg_event))
  		var->value = CStringGetTextDatum("DELETE");
  	else if (TRIGGER_FIRED_BY_TRUNCATE(trigdata->tg_event))
  		var->value = CStringGetTextDatum("TRUNCATE");
  	else
  		elog(ERROR, "unrecognized trigger action: not INSERT, DELETE, UPDATE, or TRUNCATE");
  	var->isnull = false;
  	var->freeval = true;
  
  	var = (PLpgSQL_var *) (estate.datums[func->tg_name_varno]);
  	var->value = DirectFunctionCall1(namein,
  							  CStringGetDatum(trigdata->tg_trigger->tgname));
  	var->isnull = false;
  	var->freeval = true;
  
  	var = (PLpgSQL_var *) (estate.datums[func->tg_when_varno]);
  	if (TRIGGER_FIRED_BEFORE(trigdata->tg_event))
  		var->value = CStringGetTextDatum("BEFORE");
  	else if (TRIGGER_FIRED_AFTER(trigdata->tg_event))
  		var->value = CStringGetTextDatum("AFTER");
  	else if (TRIGGER_FIRED_INSTEAD(trigdata->tg_event))
  		var->value = CStringGetTextDatum("INSTEAD OF");
  	else
  		elog(ERROR, "unrecognized trigger execution time: not BEFORE, AFTER, or INSTEAD OF");
  	var->isnull = false;
  	var->freeval = true;
  
  	var = (PLpgSQL_var *) (estate.datums[func->tg_level_varno]);
  	if (TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
  		var->value = CStringGetTextDatum("ROW");
  	else if (TRIGGER_FIRED_FOR_STATEMENT(trigdata->tg_event))
  		var->value = CStringGetTextDatum("STATEMENT");
  	else
  		elog(ERROR, "unrecognized trigger event type: not ROW or STATEMENT");
  	var->isnull = false;
  	var->freeval = true;
  
  	var = (PLpgSQL_var *) (estate.datums[func->tg_relid_varno]);
  	var->value = ObjectIdGetDatum(trigdata->tg_relation->rd_id);
  	var->isnull = false;
  	var->freeval = false;
  
  	var = (PLpgSQL_var *) (estate.datums[func->tg_relname_varno]);
  	var->value = DirectFunctionCall1(namein,
  			CStringGetDatum(RelationGetRelationName(trigdata->tg_relation)));
  	var->isnull = false;
  	var->freeval = true;
  
  	var = (PLpgSQL_var *) (estate.datums[func->tg_table_name_varno]);
  	var->value = DirectFunctionCall1(namein,
  			CStringGetDatum(RelationGetRelationName(trigdata->tg_relation)));
  	var->isnull = false;
  	var->freeval = true;
  
  	var = (PLpgSQL_var *) (estate.datums[func->tg_table_schema_varno]);
  	var->value = DirectFunctionCall1(namein,
  									 CStringGetDatum(
  													 get_namespace_name(
  														RelationGetNamespace(
  												   trigdata->tg_relation))));
  	var->isnull = false;
  	var->freeval = true;
  
  	var = (PLpgSQL_var *) (estate.datums[func->tg_nargs_varno]);
  	var->value = Int16GetDatum(trigdata->tg_trigger->tgnargs);
  	var->isnull = false;
  	var->freeval = false;
  
  	var = (PLpgSQL_var *) (estate.datums[func->tg_argv_varno]);
  	if (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 = trigdata->tg_trigger->tgnargs;
  		Datum	   *elems;
  		int			dims[1];
  		int			lbs[1];
  
  		elems = palloc(sizeof(Datum) * nelems);
  		for (i = 0; i < nelems; i++)
  			elems[i] = CStringGetTextDatum(trigdata->tg_trigger->tgargs[i]);
  		dims[0] = nelems;
  		lbs[0] = 0;
  
  		var->value = PointerGetDatum(construct_md_array(elems, NULL,
  														1, dims, lbs,
  														TEXTOID,
  														-1, false, 'i'));
  		var->isnull = false;
  		var->freeval = true;
  	}
  	else
  	{
  		var->value = (Datum) 0;
  		var->isnull = true;
  		var->freeval = false;
  	}
  
  	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 (*plugin_ptr && (*plugin_ptr)->func_beg)
  		((*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_block(&estate, func->action);
  	if (rc != PLPGSQL_RC_RETURN)
  	{
  		estate.err_stmt = NULL;
  		estate.err_text = NULL;
  
  		/*
  		 * Provide a more helpful message if a CONTINUE or RAISE has been used
  		 * outside the context it can work in.
  		 */
  		if (rc == PLPGSQL_RC_CONTINUE)
  			ereport(ERROR,
  					(errcode(ERRCODE_SYNTAX_ERROR),
  					 errmsg("CONTINUE cannot be used outside a loop")));
  		else
  			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
  	{
  		TupleConversionMap *tupmap;
  
  		rettup = (HeapTuple) DatumGetPointer(estate.retval);
  		/* check rowtype compatibility */
  		tupmap = convert_tuples_by_position(estate.rettupdesc,
  											trigdata->tg_relation->rd_att,
  											gettext_noop("returned row structure does not match the structure of the triggering table"));
  		/* it might need conversion */
  		if (tupmap)
  			rettup = do_convert_tuple(rettup, tupmap);
  		/* 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 (*plugin_ptr && (*plugin_ptr)->func_end)
  		((*plugin_ptr)->func_end) (&estate, func);
  
  	/* Clean up any leftover temporary memory */
  	plpgsql_destroy_econtext(&estate);
  	exec_eval_cleanup(&estate);
  
  	/*
  	 * Pop the error context stack
  	 */
  	error_context_stack = plerrcontext.previous;
  
  	/*
  	 * Return the trigger's result
  	 */
  	return rettup;
  }
  
  void
  plpgsql_exec_event_trigger(PLpgSQL_function *func, EventTriggerData *trigdata)
  {
  	PLpgSQL_execstate estate;
  	ErrorContextCallback plerrcontext;
  	int			i;
  	int			rc;
  	PLpgSQL_var *var;
  
  	/*
  	 * Setup the execution state
  	 */
  	plpgsql_estate_setup(&estate, func, NULL, NULL);
  
  	/*
  	 * 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");
  	for (i = 0; i < estate.ndatums; i++)
  		estate.datums[i] = copy_plpgsql_datum(func->datums[i]);
  
  	/*
  	 * Assign the special tg_ variables
  	 */
  	var = (PLpgSQL_var *) (estate.datums[func->tg_event_varno]);
  	var->value = CStringGetTextDatum(trigdata->event);
  	var->isnull = false;
  	var->freeval = true;
  
  	var = (PLpgSQL_var *) (estate.datums[func->tg_tag_varno]);
  	var->value = CStringGetTextDatum(trigdata->tag);
  	var->isnull = false;
  	var->freeval = true;
  
  	/*
  	 * Let the instrumentation plugin peek at this function
  	 */
  	if (*plugin_ptr && (*plugin_ptr)->func_beg)
  		((*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_block(&estate, func->action);
  	if (rc != PLPGSQL_RC_RETURN)
  	{
  		estate.err_stmt = NULL;
  		estate.err_text = NULL;
  
  		/*
  		 * Provide a more helpful message if a CONTINUE or RAISE has been used
  		 * outside the context it can work in.
  		 */
  		if (rc == PLPGSQL_RC_CONTINUE)
  			ereport(ERROR,
  					(errcode(ERRCODE_SYNTAX_ERROR),
  					 errmsg("CONTINUE cannot be used outside a loop")));
  		else
  			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 (*plugin_ptr && (*plugin_ptr)->func_end)
  		((*plugin_ptr)->func_end) (&estate, func);
  
  	/* Clean up any leftover temporary memory */
  	plpgsql_destroy_econtext(&estate);
  	exec_eval_cleanup(&estate);
  
  	/*
  	 * Pop the error context stack
  	 */
  	error_context_stack = plerrcontext.previous;
  
  	return;
  }
  
  /*
   * 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 we are doing RAISE, don't report its location */
  	if (estate->err_text == raise_skip_msg)
  		return;
  
  	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 PLpgSQL_datum *
  copy_plpgsql_datum(PLpgSQL_datum *datum)
  {
  	PLpgSQL_datum *result;
  
  	switch (datum->dtype)
  	{
  		case PLPGSQL_DTYPE_VAR:
  			{
  				PLpgSQL_var *new = palloc(sizeof(PLpgSQL_var));
  
  				memcpy(new, datum, sizeof(PLpgSQL_var));
  				/* Ensure the value is null (possibly not needed?) */
  				new->value = 0;
  				new->isnull = true;
  				new->freeval = false;
  
  				result = (PLpgSQL_datum *) new;
  			}
  			break;
  
  		case PLPGSQL_DTYPE_REC:
  			{
  				PLpgSQL_rec *new = palloc(sizeof(PLpgSQL_rec));
  
  				memcpy(new, datum, sizeof(PLpgSQL_rec));
  				/* Ensure the value is null (possibly not needed?) */
  				new->tup = NULL;
  				new->tupdesc = NULL;
  				new->freetup = false;
  				new->freetupdesc = false;
  
  				result = (PLpgSQL_datum *) new;
  			}
  			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, ARRAYELEM contains some cached type data, but
  			 * we'd just as soon centralize the caching anyway)
  			 */
  			result = datum;
  			break;
  
  		default:
  			elog(ERROR, "unrecognized dtype: %d", datum->dtype);
  			result = NULL;		/* keep compiler quiet */
  			break;
  	}
  
  	return result;
  }
  
  
  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; if you're
  		 * foolish enough, you can match that explicitly.
  		 */
  		if (sqlerrstate == 0)
  		{
  			if (edata->sqlerrcode != ERRCODE_QUERY_CANCELED)
  				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;
  	int			n;
  
  	/*
  	 * 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++)
  	{
  		n = block->initvarnos[i];
  
  		switch (estate->datums[n]->dtype)
  		{
  			case PLPGSQL_DTYPE_VAR:
  				{
  					PLpgSQL_var *var = (PLpgSQL_var *) (estate->datums[n]);
  
  					/* free any old value, in case re-entering block */
  					free_var(var);
  
  					/* Initially it contains a NULL */
  					var->value = (Datum) 0;
  					var->isnull = true;
  
  					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. (Do this
  						 * before the notnull check to be consistent with
  						 * exec_assign_value.)
  						 */
  						if (!var->datatype->typinput.fn_strict)
  						{
  							bool		valIsNull = true;
  
  							exec_assign_value(estate,
  											  (PLpgSQL_datum *) var,
  											  (Datum) 0,
  											  UNKNOWNOID,
  											  &valIsNull);
  						}
  						if (var->notnull)
  							ereport(ERROR,
  									(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
  									 errmsg("variable \"%s\" declared NOT NULL cannot default to NULL",
  											var->refname)));
  					}
  					else
  					{
  						exec_assign_expr(estate, (PLpgSQL_datum *) var,
  										 var->default_val);
  					}
  				}
  				break;
  
  			case PLPGSQL_DTYPE_REC:
  				{
  					PLpgSQL_rec *rec = (PLpgSQL_rec *) (estate->datums[n]);
  
  					if (rec->freetup)
  					{
  						heap_freetuple(rec->tup);
  						rec->freetup = false;
  					}
  					if (rec->freetupdesc)
  					{
  						FreeTupleDesc(rec->tupdesc);
  						rec->freetupdesc = false;
  					}
  					rec->tup = NULL;
  					rec->tupdesc = NULL;
  				}
  				break;
  
  			case PLPGSQL_DTYPE_RECFIELD:
  			case PLPGSQL_DTYPE_ARRAYELEM:
  				break;
  
  			default:
  				elog(ERROR, "unrecognized dtype: %d",
  					 estate->datums[n]->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;
  
  		estate->err_text = gettext_noop("during statement block entry");
  
  		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.  This is
  			 * currently only needed for scalar result types --- rowtype
  			 * values will always exist in the function's own memory context.
  			 */
  			if (rc == PLPGSQL_RC_RETURN &&
  				!estate->retisset &&
  				!estate->retisnull &&
  				estate->rettupdesc == NULL)
  			{
  				int16		resTypLen;
  				bool		resTypByVal;
  
  				get_typlenbyval(estate->rettype, &resTypLen, &resTypByVal);
  				estate->retval = datumCopy(estate->retval,
  										   resTypByVal, resTypLen);
  			}
  
  			/* Commit the inner transaction, return to outer xact context */
  			ReleaseCurrentSubTransaction();
  			MemoryContextSwitchTo(oldcontext);
  			CurrentResourceOwner = oldowner;
  
  			/*
  			 * Revert to outer eval_econtext.  (The inner one was
  			 * automatically cleaned up during subxact exit.)
  			 */
  			estate->eval_econtext = old_eval_econtext;
  
  			/*
  			 * AtEOSubXact_SPI() should not have popped any SPI context, but
  			 * just in case it did, make sure we remain connected.
  			 */
  			SPI_restore_connection();
  		}
  		PG_CATCH();
  		{
  			ErrorData  *edata;
  			ListCell   *e;
  
  			estate->err_text = gettext_noop("during exception cleanup");
  
  			/* Save error info */
  			MemoryContextSwitchTo(oldcontext);
  			edata = CopyErrorData();
  			FlushErrorState();
  
  			/* Abort the inner transaction */
  			RollbackAndReleaseCurrentSubTransaction();
  			MemoryContextSwitchTo(oldcontext);
  			CurrentResourceOwner = oldowner;
  
  			/* Revert to outer eval_econtext */
  			estate->eval_econtext = old_eval_econtext;
  
  			/*
  			 * If AtEOSubXact_SPI() popped any SPI context of the subxact, it
  			 * will have left us in a disconnected state.  We need this hack
  			 * to return to connected state.
  			 */
  			SPI_restore_connection();
  
  			/*
  			 * 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. 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(state_var,
  									unpack_sql_state(edata->sqlerrcode));
  					assign_text_var(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);
  
  					free_var(state_var);
  					state_var->value = (Datum) 0;
  					state_var->isnull = true;
  					free_var(errm_var);
  					errm_var->value = (Datum) 0;
  					errm_var->isnull = true;
  
  					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);
  			else
  				FreeErrorData(edata);
  		}
  		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.
  	 */
  	switch (rc)
  	{
  		case PLPGSQL_RC_OK:
  		case PLPGSQL_RC_RETURN:
  		case PLPGSQL_RC_CONTINUE:
  			return rc;
  
  		case PLPGSQL_RC_EXIT:
  
  			/*
  			 * This is intentionally different from the handling of RC_EXIT
  			 * for loops: to match a block, we require a match by label.
  			 */
  			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 (*plugin_ptr && (*plugin_ptr)->stmt_beg)
  		((*plugin_ptr)->stmt_beg) (estate, stmt);
  
  	CHECK_FOR_INTERRUPTS();
  
  	switch ((enum PLpgSQL_stmt_types) 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_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_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;
  
  		default:
  			estate->err_stmt = save_estmt;
  			elog(ERROR, "unrecognized cmdtype: %d", stmt->cmd_type);
  	}
  
  	/* Let the plugin know that we have finished executing this statement */
  	if (*plugin_ptr && (*plugin_ptr)->stmt_end)
  		((*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_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];
  		bool		isnull = false;
  
  		switch (diag_item->kind)
  		{
  			case PLPGSQL_GETDIAG_ROW_COUNT:
  				exec_assign_value(estate, var,
  								  UInt32GetDatum(estate->eval_processed),
  								  INT4OID, &isnull);
  				break;
  
  			case PLPGSQL_GETDIAG_RESULT_OID:
  				exec_assign_value(estate, var,
  								  ObjectIdGetDatum(estate->eval_lastoid),
  								  OIDOID, &isnull);
  				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 = GetErrorContextStack();
  
  					exec_assign_c_string(estate, var, contextstackstr);
  
  					pfree(contextstackstr);
  				}
  				break;
  
  			default:
  				elog(ERROR, "unrecognized diagnostic item kind: %d",
  					 diag_item->kind);
  		}
  	}
  
  	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_oid;
  
  		t_val = exec_eval_expr(estate, stmt->t_expr, &isnull, &t_oid);
  
  		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.
  		 */
  		if (t_var->datatype->typoid != t_oid)
  			t_var->datatype = plpgsql_build_datatype(t_oid,
  													 -1,
  										   estate->func->fn_input_collation);
  
  		/* now we can assign to the variable */
  		exec_assign_value(estate,
  						  (PLpgSQL_datum *) t_var,
  						  t_val,
  						  t_oid,
  						  &isnull);
  
  		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)
  			{
  				free_var(t_var);
  				t_var->value = (Datum) 0;
  				t_var->isnull = true;
  			}
  
  			/* 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)
  	{
  		free_var(t_var);
  		t_var->value = (Datum) 0;
  		t_var->isnull = true;
  	}
  
  	/* 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)
  {
  	for (;;)
  	{
  		int			rc = exec_stmts(estate, stmt->body);
  
  		switch (rc)
  		{
  			case PLPGSQL_RC_OK:
  				break;
  
  			case PLPGSQL_RC_EXIT:
  				if (estate->exitlabel == NULL)
  					return PLPGSQL_RC_OK;
  				if (stmt->label == NULL)
  					return PLPGSQL_RC_EXIT;
  				if (strcmp(stmt->label, estate->exitlabel) != 0)
  					return PLPGSQL_RC_EXIT;
  				estate->exitlabel = NULL;
  				return PLPGSQL_RC_OK;
  
  			case PLPGSQL_RC_CONTINUE:
  				if (estate->exitlabel == NULL)
  					/* anonymous continue, so re-run the loop */
  					break;
  				else if (stmt->label != NULL &&
  						 strcmp(stmt->label, estate->exitlabel) == 0)
  					/* label matches named continue, so re-run loop */
  					estate->exitlabel = NULL;
  				else
  					/* label doesn't match named continue, so propagate upward */
  					return PLPGSQL_RC_CONTINUE;
  				break;
  
  			case PLPGSQL_RC_RETURN:
  				return rc;
  
  			default:
  				elog(ERROR, "unrecognized rc: %d", 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)
  {
  	for (;;)
  	{
  		int			rc;
  		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);
  
  		switch (rc)
  		{
  			case PLPGSQL_RC_OK:
  				break;
  
  			case PLPGSQL_RC_EXIT:
  				if (estate->exitlabel == NULL)
  					return PLPGSQL_RC_OK;
  				if (stmt->label == NULL)
  					return PLPGSQL_RC_EXIT;
  				if (strcmp(stmt->label, estate->exitlabel) != 0)
  					return PLPGSQL_RC_EXIT;
  				estate->exitlabel = NULL;
  				return PLPGSQL_RC_OK;
  
  			case PLPGSQL_RC_CONTINUE:
  				if (estate->exitlabel == NULL)
  					/* anonymous continue, so re-run loop */
  					break;
  				else if (stmt->label != NULL &&
  						 strcmp(stmt->label, estate->exitlabel) == 0)
  					/* label matches named continue, so re-run loop */
  					estate->exitlabel = NULL;
  				else
  					/* label doesn't match named continue, propagate upward */
  					return PLPGSQL_RC_CONTINUE;
  				break;
  
  			case PLPGSQL_RC_RETURN:
  				return rc;
  
  			default:
  				elog(ERROR, "unrecognized rc: %d", rc);
  		}
  	}
  
  	return PLPGSQL_RC_OK;
  }
  
  
  /* ----------
   * 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		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);
  	value = exec_cast_value(estate, value, valtype, var->datatype->typoid,
  							&(var->datatype->typinput),
  							var->datatype->typioparam,
  							var->datatype->atttypmod, isnull);
  	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);
  	value = exec_cast_value(estate, value, valtype, var->datatype->typoid,
  							&(var->datatype->typinput),
  							var->datatype->typioparam,
  							var->datatype->atttypmod, isnull);
  	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);
  		value = exec_cast_value(estate, value, valtype, var->datatype->typoid,
  								&(var->datatype->typinput),
  								var->datatype->typioparam,
  								var->datatype->atttypmod, isnull);
  		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
  		 */
  		var->value = Int32GetDatum(loop_value);
  		var->isnull = false;
  
  		/*
  		 * Execute the statements
  		 */
  		rc = exec_stmts(estate, stmt->body);
  
  		if (rc == PLPGSQL_RC_RETURN)
  			break;				/* break out of the loop */
  		else if (rc == PLPGSQL_RC_EXIT)
  		{
  			if (estate->exitlabel == NULL)
  				/* unlabelled exit, finish the current loop */
  				rc = PLPGSQL_RC_OK;
  			else if (stmt->label != NULL &&
  					 strcmp(stmt->label, estate->exitlabel) == 0)
  			{
  				/* labelled exit, matches the current stmt's label */
  				estate->exitlabel = NULL;
  				rc = PLPGSQL_RC_OK;
  			}
  
  			/*
  			 * otherwise, this is a labelled exit that does not match the
  			 * current statement's label, if any: return RC_EXIT so that the
  			 * EXIT continues to propagate up the stack.
  			 */
  			break;
  		}
  		else if (rc == PLPGSQL_RC_CONTINUE)
  		{
  			if (estate->exitlabel == NULL)
  				/* unlabelled continue, so re-run the current loop */
  				rc = PLPGSQL_RC_OK;
  			else if (stmt->label != NULL &&
  					 strcmp(stmt->label, estate->exitlabel) == 0)
  			{
  				/* label matches named continue, so re-run loop */
  				estate->exitlabel = NULL;
  				rc = PLPGSQL_RC_OK;
  			}
  			else
  			{
  				/*
  				 * otherwise, this is a named continue that does not match the
  				 * current statement's label, if any: return RC_CONTINUE so
  				 * that the CONTINUE will propagate up the stack.
  				 */
  				break;
  			}
  		}
  
  		/*
  		 * Increase/decrease loop value, unless it would overflow, in which
  		 * case exit the loop.
  		 */
  		if (stmt->reverse)
  		{
  			if ((int32) (loop_value - step_value) > loop_value)
  				break;
  			loop_value -= step_value;
  		}
  		else
  		{
  			if ((int32) (loop_value + step_value) < loop_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;
  	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)
  	{
  		curname = TextDatumGetCString(curvar->value);
  		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.row = (PLpgSQL_row *)
  			(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);
  
  	/*
  	 * Set up ParamListInfo (hook function and possibly data values)
  	 */
  	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));
  
  	/* don't need paramlist any more */
  	if (paramLI)
  		pfree(paramLI);
  
  	/*
  	 * If cursor variable was NULL, store the generated portal name in it
  	 */
  	if (curname == NULL)
  		assign_text_var(curvar, portal->name);
  
  	/*
  	 * 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)
  	{
  		free_var(curvar);
  		curvar->value = (Datum) 0;
  		curvar->isnull = true;
  	}
  
  	if (curname)
  		pfree(curname);
  
  	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;
  	PLpgSQL_datum *loop_var;
  	Oid			loop_var_elem_type;
  	bool		found = false;
  	int			rc = PLPGSQL_RC_OK;
  	ArrayIterator array_iterator;
  	Oid			iterator_result_type;
  	Datum		value;
  	bool		isnull;
  
  	/* get the value of the array expression */
  	value = exec_eval_expr(estate, stmt->expr, &isnull, &arrtype);
  	if (isnull)
  		ereport(ERROR,
  				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
  				 errmsg("FOREACH expression must not be null")));
  
  	/* 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, 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(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);
  
  	/* Identify iterator result type */
  	if (stmt->slice > 0)
  	{
  		/* When slicing, nominal type of result is same as array type */
  		iterator_result_type = arrtype;
  	}
  	else
  	{
  		/* Without slicing, results are individual array elements */
  		iterator_result_type = ARR_ELEMTYPE(arr);
  	}
  
  	/* Iterate over the array elements or slices */
  	while (array_iterate(array_iterator, &value, &isnull))
  	{
  		found = true;			/* looped at least once */
  
  		/* Assign current element/slice to the loop variable */
  		exec_assign_value(estate, loop_var, value, iterator_result_type,
  						  &isnull);
  
  		/* 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);
  
  		/* Handle the return code */
  		if (rc == PLPGSQL_RC_RETURN)
  			break;				/* break out of the loop */
  		else if (rc == PLPGSQL_RC_EXIT)
  		{
  			if (estate->exitlabel == NULL)
  				/* unlabelled exit, finish the current loop */
  				rc = PLPGSQL_RC_OK;
  			else if (stmt->label != NULL &&
  					 strcmp(stmt->label, estate->exitlabel) == 0)
  			{
  				/* labelled exit, matches the current stmt's label */
  				estate->exitlabel = NULL;
  				rc = PLPGSQL_RC_OK;
  			}
  
  			/*
  			 * otherwise, this is a labelled exit that does not match the
  			 * current statement's label, if any: return RC_EXIT so that the
  			 * EXIT continues to propagate up the stack.
  			 */
  			break;
  		}
  		else if (rc == PLPGSQL_RC_CONTINUE)
  		{
  			if (estate->exitlabel == NULL)
  				/* unlabelled continue, so re-run the current loop */
  				rc = PLPGSQL_RC_OK;
  			else if (stmt->label != NULL &&
  					 strcmp(stmt->label, estate->exitlabel) == 0)
  			{
  				/* label matches named continue, so re-run loop */
  				estate->exitlabel = NULL;
  				rc = PLPGSQL_RC_OK;
  			}
  			else
  			{
  				/*
  				 * otherwise, this is a named continue that does not match the
  				 * current statement's label, if any: return RC_CONTINUE so
  				 * that the CONTINUE will propagate up the stack.
  				 */
  				break;
  			}
  		}
  	}
  
  	/* Release temporary memory, including the array value */
  	array_free_iterator(array_iterator);
  	pfree(arr);
  
  	/*
  	 * 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.
   * ----------
   */
  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 (possibly a tuple) */
  	estate->retval = (Datum) 0;
  	estate->rettupdesc = NULL;
  	estate->retisnull = true;
  
  	/*
  	 * This special-case path covers record/row variables in fn_retistuple
  	 * functions, as well as functions with one or more OUT parameters.
  	 */
  	if (stmt->retvarno >= 0)
  	{
  		PLpgSQL_datum *retvar = estate->datums[stmt->retvarno];
  
  		switch (retvar->dtype)
  		{
  			case PLPGSQL_DTYPE_VAR:
  				{
  					PLpgSQL_var *var = (PLpgSQL_var *) retvar;
  
  					estate->retval = var->value;
  					estate->retisnull = var->isnull;
  					estate->rettype = var->datatype->typoid;
  				}
  				break;
  
  			case PLPGSQL_DTYPE_REC:
  				{
  					PLpgSQL_rec *rec = (PLpgSQL_rec *) retvar;
  
  					if (HeapTupleIsValid(rec->tup))
  					{
  						estate->retval = PointerGetDatum(rec->tup);
  						estate->rettupdesc = rec->tupdesc;
  						estate->retisnull = false;
  					}
  				}
  				break;
  
  			case PLPGSQL_DTYPE_ROW:
  				{
  					PLpgSQL_row *row = (PLpgSQL_row *) retvar;
  
  					Assert(row->rowtupdesc);
  					estate->retval =
  						PointerGetDatum(make_tuple_from_row(estate, row,
  															row->rowtupdesc));
  					if (DatumGetPointer(estate->retval) == NULL)		/* should not happen */
  						elog(ERROR, "row not compatible with its own tupdesc");
  					estate->rettupdesc = row->rowtupdesc;
  					estate->retisnull = false;
  				}
  				break;
  
  			default:
  				elog(ERROR, "unrecognized dtype: %d", retvar->dtype);
  		}
  
  		return PLPGSQL_RC_RETURN;
  	}
  
  	if (stmt->expr != NULL)
  	{
  		estate->retval = exec_eval_expr(estate, stmt->expr,
  										&(estate->retisnull),
  										&(estate->rettype));
  
  		if (estate->retistuple && !estate->retisnull)
  		{
  			/* Convert composite datum to a HeapTuple and TupleDesc */
  			HeapTuple	tuple;
  			TupleDesc	tupdesc;
  
  			/* Source must be of RECORD or composite type */
  			if (!type_is_rowtype(estate->rettype))
  				ereport(ERROR,
  						(errcode(ERRCODE_DATATYPE_MISMATCH),
  						 errmsg("cannot return non-composite value from function returning composite type")));
  			tuple = get_tuple_from_datum(estate->retval);
  			tupdesc = get_tupdesc_from_datum(estate->retval);
  			estate->retval = PointerGetDatum(tuple);
  			estate->rettupdesc = CreateTupleDescCopy(tupdesc);
  			ReleaseTupleDesc(tupdesc);
  		}
  
  		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.
  	 */
  	if (estate->fn_rettype == VOIDOID)
  	{
  		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 = NULL;
  	bool		free_tuple = false;
  
  	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);
  
  	/* rettupdesc will be filled by exec_init_tuple_store */
  	tupdesc = estate->rettupdesc;
  	natts = tupdesc->natts;
  
  	/*
  	 * This special-case path covers record/row variables in fn_retistuple
  	 * functions, as well as functions with one or more OUT parameters.
  	 */
  	if (stmt->retvarno >= 0)
  	{
  		PLpgSQL_datum *retvar = estate->datums[stmt->retvarno];
  
  		switch (retvar->dtype)
  		{
  			case PLPGSQL_DTYPE_VAR:
  				{
  					PLpgSQL_var *var = (PLpgSQL_var *) retvar;
  					Datum		retval = var->value;
  					bool		isNull = var->isnull;
  
  					if (natts != 1)
  						ereport(ERROR,
  								(errcode(ERRCODE_DATATYPE_MISMATCH),
  						errmsg("wrong result type supplied in RETURN NEXT")));
  
  					/* coerce type if needed */
  					retval = exec_simple_cast_value(estate,
  													retval,
  													var->datatype->typoid,
  												 tupdesc->attrs[0]->atttypid,
  												tupdesc->attrs[0]->atttypmod,
  													isNull);
  
  					tuplestore_putvalues(estate->tuple_store, tupdesc,
  										 &retval, &isNull);
  				}
  				break;
  
  			case PLPGSQL_DTYPE_REC:
  				{
  					PLpgSQL_rec *rec = (PLpgSQL_rec *) retvar;
  					TupleConversionMap *tupmap;
  
  					if (!HeapTupleIsValid(rec->tup))
  						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.")));
  					tupmap = convert_tuples_by_position(rec->tupdesc,
  														tupdesc,
  														gettext_noop("wrong record type supplied in RETURN NEXT"));
  					tuple = rec->tup;
  					/* it might need conversion */
  					if (tupmap)
  					{
  						tuple = do_convert_tuple(tuple, tupmap);
  						free_conversion_map(tupmap);
  						free_tuple = true;
  					}
  				}
  				break;
  
  			case PLPGSQL_DTYPE_ROW:
  				{
  					PLpgSQL_row *row = (PLpgSQL_row *) retvar;
  
  					tuple = make_tuple_from_row(estate, row, tupdesc);
  					if (tuple == NULL)
  						ereport(ERROR,
  								(errcode(ERRCODE_DATATYPE_MISMATCH),
  						errmsg("wrong record type supplied in RETURN NEXT")));
  					free_tuple = true;
  				}
  				break;
  
  			default:
  				elog(ERROR, "unrecognized dtype: %d", retvar->dtype);
  				break;
  		}
  	}
  	else if (stmt->expr)
  	{
  		Datum		retval;
  		bool		isNull;
  		Oid			rettype;
  
  		retval = exec_eval_expr(estate,
  								stmt->expr,
  								&isNull,
  								&rettype);
  
  		if (estate->retistuple)
  		{
  			/* Expression should be of RECORD or composite type */
  			if (!isNull)
  			{
  				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")));
  
  				tuple = get_tuple_from_datum(retval);
  				free_tuple = true;		/* tuple is always freshly palloc'd */
  
  				/* it might need conversion */
  				retvaldesc = get_tupdesc_from_datum(retval);
  				tupmap = convert_tuples_by_position(retvaldesc, tupdesc,
  													gettext_noop("returned record type does not match expected record type"));
  				if (tupmap)
  				{
  					HeapTuple	newtuple;
  
  					newtuple = do_convert_tuple(tuple, tupmap);
  					free_conversion_map(tupmap);
  					heap_freetuple(tuple);
  					tuple = newtuple;
  				}
  				ReleaseTupleDesc(retvaldesc);
  				/* tuple will be stored into tuplestore below */
  			}
  			else
  			{
  				/* Composite NULL --- store a row of nulls */
  				Datum	   *nulldatums;
  				bool	   *nullflags;
  
  				nulldatums = (Datum *) palloc0(natts * sizeof(Datum));
  				nullflags = (bool *) palloc(natts * sizeof(bool));
  				memset(nullflags, true, natts * sizeof(bool));
  				tuplestore_putvalues(estate->tuple_store, tupdesc,
  									 nulldatums, nullflags);
  				pfree(nulldatums);
  				pfree(nullflags);
  			}
  		}
  		else
  		{
  			/* 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_simple_cast_value(estate,
  											retval,
  											rettype,
  											tupdesc->attrs[0]->atttypid,
  											tupdesc->attrs[0]->atttypmod,
  											isNull);
  
  			tuplestore_putvalues(estate->tuple_store, tupdesc,
  								 &retval, &isNull);
  		}
  	}
  	else
  	{
  		ereport(ERROR,
  				(errcode(ERRCODE_SYNTAX_ERROR),
  				 errmsg("RETURN NEXT must have a parameter")));
  	}
  
  	if (HeapTupleIsValid(tuple))
  	{
  		tuplestore_puttuple(estate->tuple_store, tuple);
  
  		if (free_tuple)
  			heap_freetuple(tuple);
  	}
  
  	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;
  	uint32		processed = 0;
  	TupleConversionMap *tupmap;
  
  	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);
  	}
  
  	tupmap = convert_tuples_by_position(portal->tupDesc,
  										estate->rettupdesc,
  	 gettext_noop("structure of query does not match function result type"));
  
  	while (true)
  	{
  		int			i;
  
  		SPI_cursor_fetch(portal, true, 50);
  		if (SPI_processed == 0)
  			break;
  
  		for (i = 0; i < SPI_processed; i++)
  		{
  			HeapTuple	tuple = SPI_tuptable->vals[i];
  
  			if (tupmap)
  				tuple = do_convert_tuple(tuple, tupmap);
  			tuplestore_puttuple(estate->tuple_store, tuple);
  			if (tupmap)
  				heap_freetuple(tuple);
  			processed++;
  		}
  
  		SPI_freetuptable(SPI_tuptable);
  	}
  
  	if (tupmap)
  		free_conversion_map(tupmap);
  
  	SPI_freetuptable(SPI_tuptable);
  	SPI_cursor_close(portal);
  
  	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->rettupdesc = 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 = pstrdup(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;
  	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")));
  	}
  
  	if (stmt->condname)
  	{
  		err_code = plpgsql_recognize_err_condition(stmt->condname, true);
  		condname = pstrdup(stmt->condname);
  	}
  
  	if (stmt->message)
  	{
  		StringInfoData ds;
  		ListCell   *current_param;
  		char	   *cp;
  
  		initStringInfo(&ds);
  		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;
  				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);
  
  				if (paramisnull)
  					extval = "<NULL>";
  				else
  					extval = convert_value_to_string(estate,
  													 paramvalue,
  													 paramtypeid);
  				appendStringInfoString(&ds, extval);
  				current_param = lnext(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;
  		/* No pfree(ds.data), the pfree(err_message) does it */
  	}
  
  	foreach(lc, stmt->options)
  	{
  		PLpgSQL_raise_option *opt = (PLpgSQL_raise_option *) lfirst(lc);
  		Datum		optionvalue;
  		bool		optionisnull;
  		Oid			optiontypeid;
  		char	   *extval;
  
  		optionvalue = exec_eval_expr(estate, opt->expr,
  									 &optionisnull,
  									 &optiontypeid);
  		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 = pstrdup(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 = pstrdup(unpack_sql_state(err_code));
  	}
  
  	/*
  	 * Throw the error (may or may not come back)
  	 */
  	estate->err_text = raise_skip_msg;	/* suppress traceback of raise */
  
  	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));
  
  	estate->err_text = NULL;	/* un-suppress... */
  
  	if (condname != NULL)
  		pfree(condname);
  	if (err_message != NULL)
  		pfree(err_message);
  	if (err_detail != NULL)
  		pfree(err_detail);
  	if (err_hint != NULL)
  		pfree(err_hint);
  	if (err_column != NULL)
  		pfree(err_column);
  	if (err_constraint != NULL)
  		pfree(err_constraint);
  	if (err_datatype != NULL)
  		pfree(err_datatype);
  	if (err_table != NULL)
  		pfree(err_table);
  	if (err_schema != NULL)
  		pfree(err_schema);
  
  	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)
  {
  	/* this link will be restored at exit from plpgsql_call_handler */
  	func->cur_estate = estate;
  
  	estate->func = func;
  
  	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->rettupdesc = NULL;
  	estate->exitlabel = NULL;
  	estate->cur_error = NULL;
  
  	estate->tuple_store = 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 = palloc(sizeof(PLpgSQL_datum *) * estate->ndatums);
  	/* caller is expected to fill the datums array */
  
  	/* set up for use of appropriate simple-expression EState */
  	if (simple_eval_estate)
  		estate->simple_eval_estate = simple_eval_estate;
  	else
  		estate->simple_eval_estate = shared_simple_eval_estate;
  
  	estate->eval_tuptable = NULL;
  	estate->eval_processed = 0;
  	estate->eval_lastoid = InvalidOid;
  	estate->eval_econtext = NULL;
  	estate->cur_expr = 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 (*plugin_ptr)
  	{
  		(*plugin_ptr)->error_callback = plpgsql_exec_error_callback;
  		(*plugin_ptr)->assign_expr = exec_assign_expr;
  
  		if ((*plugin_ptr)->func_setup)
  			((*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.
   * ----------
   */
  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) */
  	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)
  {
  	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)
  	{
  		/* Some SPI errors deserve specific error messages */
  		switch (SPI_result)
  		{
  			case SPI_ERROR_COPY:
  				ereport(ERROR,
  						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  						 errmsg("cannot COPY to/from client in PL/pgSQL")));
  			case SPI_ERROR_TRANSACTION:
  				ereport(ERROR,
  						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  						 errmsg("cannot begin/end transactions in PL/pgSQL"),
  						 errhint("Use a BEGIN block with an EXCEPTION clause instead.")));
  			default:
  				elog(ERROR, "SPI_prepare_params failed for \"%s\": %s",
  					 expr->query, SPI_result_code_string(SPI_result));
  		}
  	}
  	SPI_keepplan(plan);
  	expr->plan = plan;
  
  	/* Check to see if it's a simple expression */
  	exec_simple_check_plan(expr);
  }
  
  
  /* ----------
   * exec_stmt_execsql			Execute an SQL statement (possibly with INTO).
   * ----------
   */
  static int
  exec_stmt_execsql(PLpgSQL_execstate *estate,
  				  PLpgSQL_stmt_execsql *stmt)
  {
  	ParamListInfo paramLI;
  	long		tcount;
  	int			rc;
  	PLpgSQL_expr *expr = stmt->sqlstmt;
  
  	/*
  	 * 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, 0);
  		stmt->mod_stmt = false;
  		foreach(l, SPI_plan_get_plan_sources(expr->plan))
  		{
  			CachedPlanSource *plansource = (CachedPlanSource *) lfirst(l);
  			ListCell   *l2;
  
  			foreach(l2, plansource->query_list)
  			{
  				Query	   *q = (Query *) lfirst(l2);
  
  				Assert(IsA(q, Query));
  				if (q->canSetTag)
  				{
  					if (q->commandType == CMD_INSERT ||
  						q->commandType == CMD_UPDATE ||
  						q->commandType == CMD_DELETE)
  						stmt->mod_stmt = true;
  				}
  			}
  		}
  	}
  
  	/*
  	 * Set up ParamListInfo (hook function and possibly data values)
  	 */
  	paramLI = setup_param_list(estate, expr);
  
  	/*
  	 * If we have INTO, then we only need one row back ... but if we have INTO
  	 * STRICT, 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)
  			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:
  			Assert(!stmt->mod_stmt);
  
  			/*
  			 * 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.
  			 */
  			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")));
  		case SPI_ERROR_TRANSACTION:
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("cannot begin/end transactions in PL/pgSQL"),
  			errhint("Use a BEGIN block with an EXCEPTION clause instead.")));
  
  		default:
  			elog(ERROR, "SPI_execute_plan_with_paramlist failed executing query \"%s\": %s",
  				 expr->query, SPI_result_code_string(rc));
  	}
  
  	/* All variants should save result info for GET DIAGNOSTICS */
  	estate->eval_processed = SPI_processed;
  	estate->eval_lastoid = SPI_lastoid;
  
  	/* Process INTO if present */
  	if (stmt->into)
  	{
  		SPITupleTable *tuptab = SPI_tuptable;
  		uint32		n = SPI_processed;
  		PLpgSQL_rec *rec = NULL;
  		PLpgSQL_row *row = NULL;
  
  		/* 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")));
  
  		/* Determine if we assign to a record or a row */
  		if (stmt->rec != NULL)
  			rec = (PLpgSQL_rec *) (estate->datums[stmt->rec->dno]);
  		else if (stmt->row != NULL)
  			row = (PLpgSQL_row *) (estate->datums[stmt->row->dno]);
  		else
  			elog(ERROR, "unsupported target");
  
  		/*
  		 * 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, rec, row, NULL, tuptab->tupdesc);
  		}
  		else
  		{
  			if (n > 1 && (stmt->strict || stmt->mod_stmt))
  			{
  				char	   *errdetail;
  
  				if (estate->func->print_strict_params)
  					errdetail = format_expr_params(estate, expr);
  				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, rec, row, 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));
  	}
  
  	if (paramLI)
  		pfree(paramLI);
  
  	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 = false;
  	Oid			restype;
  	char	   *querystr;
  	int			exec_res;
  	PreparedParamsData *ppd = NULL;
  
  	/*
  	 * 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);
  	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 out of the temporary context before we clean up */
  	querystr = pstrdup(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")));
  		case SPI_ERROR_TRANSACTION:
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("cannot begin/end transactions in PL/pgSQL"),
  			errhint("Use a BEGIN block with an EXCEPTION clause instead.")));
  
  		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;
  	estate->eval_lastoid = SPI_lastoid;
  
  	/* Process INTO if present */
  	if (stmt->into)
  	{
  		SPITupleTable *tuptab = SPI_tuptable;
  		uint32		n = SPI_processed;
  		PLpgSQL_rec *rec = NULL;
  		PLpgSQL_row *row = NULL;
  
  		/* 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")));
  
  		/* Determine if we assign to a record or a row */
  		if (stmt->rec != NULL)
  			rec = (PLpgSQL_rec *) (estate->datums[stmt->rec->dno]);
  		else if (stmt->row != NULL)
  			row = (PLpgSQL_row *) (estate->datums[stmt->row->dno]);
  		else
  			elog(ERROR, "unsupported target");
  
  		/*
  		 * 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, rec, row, 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, rec, row, 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.
  		 */
  	}
  
  	if (ppd)
  		free_params_data(ppd);
  
  	/* Release any result from SPI_execute, as well as the querystring */
  	SPI_freetuptable(SPI_tuptable);
  	pfree(querystr);
  
  	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;
  	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)
  	{
  		curname = TextDatumGetCString(curvar->value);
  		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);
  	}
  	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
  		 */
  		if (curname == NULL)
  			assign_text_var(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.row = (PLpgSQL_row *)
  				(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);
  	}
  
  	/*
  	 * Set up ParamListInfo (hook function and possibly data values)
  	 */
  	paramLI = setup_param_list(estate, query);
  
  	/*
  	 * Open the cursor
  	 */
  	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(curvar, portal->name);
  
  	if (curname)
  		pfree(curname);
  	if (paramLI)
  		pfree(paramLI);
  
  	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 = NULL;
  	PLpgSQL_rec *rec = NULL;
  	PLpgSQL_row *row = NULL;
  	long		how_many = stmt->how_many;
  	SPITupleTable *tuptab;
  	Portal		portal;
  	char	   *curname;
  	uint32		n;
  
  	/* ----------
  	 * 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)));
  	curname = TextDatumGetCString(curvar->value);
  
  	portal = SPI_cursor_find(curname);
  	if (portal == NULL)
  		ereport(ERROR,
  				(errcode(ERRCODE_UNDEFINED_CURSOR),
  				 errmsg("cursor \"%s\" does not exist", curname)));
  	pfree(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)
  	{
  		/* ----------
  		 * Determine if we fetch into a record or a row
  		 * ----------
  		 */
  		if (stmt->rec != NULL)
  			rec = (PLpgSQL_rec *) (estate->datums[stmt->rec->dno]);
  		else if (stmt->row != NULL)
  			row = (PLpgSQL_row *) (estate->datums[stmt->row->dno]);
  		else
  			elog(ERROR, "unsupported 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.
  		 * ----------
  		 */
  		if (n == 0)
  			exec_move_row(estate, rec, row, NULL, tuptab->tupdesc);
  		else
  			exec_move_row(estate, rec, row, 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 = NULL;
  	Portal		portal;
  	char	   *curname;
  
  	/* ----------
  	 * 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)));
  	curname = TextDatumGetCString(curvar->value);
  
  	portal = SPI_cursor_find(curname);
  	if (portal == NULL)
  		ereport(ERROR,
  				(errcode(ERRCODE_UNDEFINED_CURSOR),
  				 errmsg("cursor \"%s\" does not exist", curname)));
  	pfree(curname);
  
  	/* ----------
  	 * And close it.
  	 * ----------
  	 */
  	SPI_cursor_close(portal);
  
  	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;
  	Oid			valtype;
  	bool		isnull = false;
  
  	value = exec_eval_expr(estate, expr, &isnull, &valtype);
  	exec_assign_value(estate, target, value, valtype, &isnull);
  	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.
   * ----------
   */
  static void
  exec_assign_c_string(PLpgSQL_execstate *estate, PLpgSQL_datum *target,
  					 const char *str)
  {
  	text	   *value;
  	bool		isnull = false;
  
  	if (str != NULL)
  		value = cstring_to_text(str);
  	else
  		value = cstring_to_text("");
  	exec_assign_value(estate, target, PointerGetDatum(value),
  					  TEXTOID, &isnull);
  	pfree(value);
  }
  
  
  /* ----------
   * exec_assign_value			Put a value into a target field
   *
   * Note: in some code paths, this will leak memory in the eval_econtext;
   * 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, Oid valtype, bool *isNull)
  {
  	switch (target->dtype)
  	{
  		case PLPGSQL_DTYPE_VAR:
  			{
  				/*
  				 * Target is a variable
  				 */
  				PLpgSQL_var *var = (PLpgSQL_var *) target;
  				Datum		newvalue;
  
  				newvalue = exec_cast_value(estate,
  										   value,
  										   valtype,
  										   var->datatype->typoid,
  										   &(var->datatype->typinput),
  										   var->datatype->typioparam,
  										   var->datatype->atttypmod,
  										   *isNull);
  
  				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_econtext) into the procedure's memory
  				 * context.
  				 */
  				if (!var->datatype->typbyval && !*isNull)
  					newvalue = datumCopy(newvalue,
  										 false,
  										 var->datatype->typlen);
  
  				/*
  				 * Now free the old value.  (We can't do this any earlier
  				 * because of the possibility that we are assigning the var's
  				 * old value to it, eg "foo := foo".  We could optimize out
  				 * the assignment altogether in such cases, but it's too
  				 * infrequent to be worth testing for.)
  				 */
  				free_var(var);
  
  				var->value = newvalue;
  				var->isnull = *isNull;
  				if (!var->datatype->typbyval && !*isNull)
  					var->freeval = true;
  				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, NULL, 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, NULL, row, value);
  				}
  				break;
  			}
  
  		case PLPGSQL_DTYPE_REC:
  			{
  				/*
  				 * Target is a record variable
  				 */
  				PLpgSQL_rec *rec = (PLpgSQL_rec *) target;
  
  				if (*isNull)
  				{
  					/* If source is null, just assign nulls to the record */
  					exec_move_row(estate, rec, NULL, 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, rec, NULL, value);
  				}
  				break;
  			}
  
  		case PLPGSQL_DTYPE_RECFIELD:
  			{
  				/*
  				 * Target is a field of a record
  				 */
  				PLpgSQL_recfield *recfield = (PLpgSQL_recfield *) target;
  				PLpgSQL_rec *rec;
  				int			fno;
  				HeapTuple	newtup;
  				int			natts;
  				Datum	   *values;
  				bool	   *nulls;
  				bool	   *replaces;
  				bool		attisnull;
  				Oid			atttype;
  				int32		atttypmod;
  
  				rec = (PLpgSQL_rec *) (estate->datums[recfield->recparentno]);
  
  				/*
  				 * Check that there is already a tuple in the record. We need
  				 * that because records don't have any predefined field
  				 * structure.
  				 */
  				if (!HeapTupleIsValid(rec->tup))
  					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.")));
  
  				/*
  				 * Get the number of the records field to change and the
  				 * number of attributes in the tuple.  Note: disallow system
  				 * column names because the code below won't cope.
  				 */
  				fno = SPI_fnumber(rec->tupdesc, recfield->fieldname);
  				if (fno <= 0)
  					ereport(ERROR,
  							(errcode(ERRCODE_UNDEFINED_COLUMN),
  							 errmsg("record \"%s\" has no field \"%s\"",
  									rec->refname, recfield->fieldname)));
  				fno--;
  				natts = rec->tupdesc->natts;
  
  				/*
  				 * Set up values/control arrays for heap_modify_tuple. For all
  				 * the attributes except the one we want to replace, use the
  				 * value that's in the old tuple.
  				 */
  				values = palloc(sizeof(Datum) * natts);
  				nulls = palloc(sizeof(bool) * natts);
  				replaces = palloc(sizeof(bool) * natts);
  
  				memset(replaces, false, sizeof(bool) * natts);
  				replaces[fno] = true;
  
  				/*
  				 * Now insert the new value, being careful to cast it to the
  				 * right type.
  				 */
  				atttype = SPI_gettypeid(rec->tupdesc, fno + 1);
  				atttypmod = rec->tupdesc->attrs[fno]->atttypmod;
  				attisnull = *isNull;
  				values[fno] = exec_simple_cast_value(estate,
  													 value,
  													 valtype,
  													 atttype,
  													 atttypmod,
  													 attisnull);
  				nulls[fno] = attisnull;
  
  				/*
  				 * Now call heap_modify_tuple() to create a new tuple that
  				 * replaces the old one in the record.
  				 */
  				newtup = heap_modify_tuple(rec->tup, rec->tupdesc,
  										   values, nulls, replaces);
  
  				if (rec->freetup)
  					heap_freetuple(rec->tup);
  
  				rec->tup = newtup;
  				rec->freetup = true;
  
  				pfree(values);
  				pfree(nulls);
  				pfree(replaces);
  
  				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,
  							coerced_value;
  				bool		oldarrayisnull;
  				Oid			parenttypoid;
  				int32		parenttypmod;
  				ArrayType  *oldarrayval;
  				ArrayType  *newarrayval;
  				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 ExecEvalArrayRef(), 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_simple_cast_value(estate,
  													   value,
  													   valtype,
  													   arrayelem->elemtypoid,
  													   arrayelem->arraytypmod,
  													   *isNull);
  
  				/*
  				 * 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 ExecEvalArrayRef().
  				 */
  				if (arrayelem->arraytyplen > 0 &&		/* fixed-length array? */
  					(oldarrayisnull || *isNull))
  					return;
  
  				/* oldarrayval and newarrayval should be short-lived */
  				oldcontext = MemoryContextSwitchTo(estate->eval_econtext->ecxt_per_tuple_memory);
  
  				if (oldarrayisnull)
  					oldarrayval = construct_empty_array(arrayelem->elemtypoid);
  				else
  					oldarrayval = (ArrayType *) DatumGetPointer(oldarraydatum);
  
  				/*
  				 * Build the modified array value.
  				 */
  				newarrayval = array_set(oldarrayval,
  										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.
  				 */
  				*isNull = false;
  				exec_assign_value(estate, target,
  								  PointerGetDatum(newarrayval),
  								  arrayelem->arraytypoid, isNull);
  				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.
   *
   * NOTE: caller must not modify the returned value, since it points right
   * at the stored value in the case of pass-by-reference datatypes.  In some
   * cases we have to palloc a return value, and in such cases we put it into
   * the estate's short-term memory context.
   */
  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_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;
  
  				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(estate->eval_econtext->ecxt_per_tuple_memory);
  				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 (!HeapTupleIsValid(rec->tup))
  					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.")));
  				Assert(rec->tupdesc != NULL);
  				/* Make sure we have a valid type/typmod setting */
  				BlessTupleDesc(rec->tupdesc);
  
  				oldcontext = MemoryContextSwitchTo(estate->eval_econtext->ecxt_per_tuple_memory);
  				*typeid = rec->tupdesc->tdtypeid;
  				*typetypmod = rec->tupdesc->tdtypmod;
  				*value = heap_copy_tuple_as_datum(rec->tup, rec->tupdesc);
  				*isnull = false;
  				MemoryContextSwitchTo(oldcontext);
  				break;
  			}
  
  		case PLPGSQL_DTYPE_RECFIELD:
  			{
  				PLpgSQL_recfield *recfield = (PLpgSQL_recfield *) datum;
  				PLpgSQL_rec *rec;
  				int			fno;
  
  				rec = (PLpgSQL_rec *) (estate->datums[recfield->recparentno]);
  				if (!HeapTupleIsValid(rec->tup))
  					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.")));
  				fno = SPI_fnumber(rec->tupdesc, recfield->fieldname);
  				if (fno == SPI_ERROR_NOATTRIBUTE)
  					ereport(ERROR,
  							(errcode(ERRCODE_UNDEFINED_COLUMN),
  							 errmsg("record \"%s\" has no field \"%s\"",
  									rec->refname, recfield->fieldname)));
  				*typeid = SPI_gettypeid(rec->tupdesc, fno);
  				if (fno > 0)
  					*typetypmod = rec->tupdesc->attrs[fno - 1]->atttypmod;
  				else
  					*typetypmod = -1;
  				*value = SPI_getbinval(rec->tup, rec->tupdesc, fno, isnull);
  				break;
  			}
  
  		default:
  			elog(ERROR, "unrecognized dtype: %d", datum->dtype);
  	}
  }
  
  /*
   * exec_get_datum_type				Get datatype of a PLpgSQL_datum
   *
   * This is the same logic as in exec_eval_datum, except that it can handle
   * some cases where exec_eval_datum has to fail; specifically, we may have
   * a tupdesc but no row value for a record variable.  (This currently can
   * happen only for a trigger's NEW/OLD records.)
   */
  Oid
  exec_get_datum_type(PLpgSQL_execstate *estate,
  					PLpgSQL_datum *datum)
  {
  	Oid			typeid;
  
  	switch (datum->dtype)
  	{
  		case PLPGSQL_DTYPE_VAR:
  			{
  				PLpgSQL_var *var = (PLpgSQL_var *) datum;
  
  				typeid = var->datatype->typoid;
  				break;
  			}
  
  		case PLPGSQL_DTYPE_ROW:
  			{
  				PLpgSQL_row *row = (PLpgSQL_row *) datum;
  
  				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);
  				typeid = row->rowtupdesc->tdtypeid;
  				break;
  			}
  
  		case PLPGSQL_DTYPE_REC:
  			{
  				PLpgSQL_rec *rec = (PLpgSQL_rec *) datum;
  
  				if (rec->tupdesc == NULL)
  					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 we have a valid type/typmod setting */
  				BlessTupleDesc(rec->tupdesc);
  				typeid = rec->tupdesc->tdtypeid;
  				break;
  			}
  
  		case PLPGSQL_DTYPE_RECFIELD:
  			{
  				PLpgSQL_recfield *recfield = (PLpgSQL_recfield *) datum;
  				PLpgSQL_rec *rec;
  				int			fno;
  
  				rec = (PLpgSQL_rec *) (estate->datums[recfield->recparentno]);
  				if (rec->tupdesc == NULL)
  					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.")));
  				fno = SPI_fnumber(rec->tupdesc, recfield->fieldname);
  				if (fno == SPI_ERROR_NOATTRIBUTE)
  					ereport(ERROR,
  							(errcode(ERRCODE_UNDEFINED_COLUMN),
  							 errmsg("record \"%s\" has no field \"%s\"",
  									rec->refname, recfield->fieldname)));
  				typeid = SPI_gettypeid(rec->tupdesc, fno);
  				break;
  			}
  
  		default:
  			elog(ERROR, "unrecognized dtype: %d", datum->dtype);
  			typeid = InvalidOid;	/* keep compiler quiet */
  			break;
  	}
  
  	return typeid;
  }
  
  /*
   * exec_get_datum_type_info			Get datatype etc of a PLpgSQL_datum
   *
   * An extended version of exec_get_datum_type, which also retrieves the
   * typmod and collation of the datum.
   */
  void
  exec_get_datum_type_info(PLpgSQL_execstate *estate,
  						 PLpgSQL_datum *datum,
  						 Oid *typeid, int32 *typmod, Oid *collation)
  {
  	switch (datum->dtype)
  	{
  		case PLPGSQL_DTYPE_VAR:
  			{
  				PLpgSQL_var *var = (PLpgSQL_var *) datum;
  
  				*typeid = var->datatype->typoid;
  				*typmod = var->datatype->atttypmod;
  				*collation = var->datatype->collation;
  				break;
  			}
  
  		case PLPGSQL_DTYPE_ROW:
  			{
  				PLpgSQL_row *row = (PLpgSQL_row *) datum;
  
  				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);
  				*typeid = row->rowtupdesc->tdtypeid;
  				/* do NOT return the mutable typmod of a RECORD variable */
  				*typmod = -1;
  				/* composite types are never collatable */
  				*collation = InvalidOid;
  				break;
  			}
  
  		case PLPGSQL_DTYPE_REC:
  			{
  				PLpgSQL_rec *rec = (PLpgSQL_rec *) datum;
  
  				if (rec->tupdesc == NULL)
  					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 we have a valid type/typmod setting */
  				BlessTupleDesc(rec->tupdesc);
  				*typeid = rec->tupdesc->tdtypeid;
  				/* 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;
  				int			fno;
  
  				rec = (PLpgSQL_rec *) (estate->datums[recfield->recparentno]);
  				if (rec->tupdesc == NULL)
  					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.")));
  				fno = SPI_fnumber(rec->tupdesc, recfield->fieldname);
  				if (fno == SPI_ERROR_NOATTRIBUTE)
  					ereport(ERROR,
  							(errcode(ERRCODE_UNDEFINED_COLUMN),
  							 errmsg("record \"%s\" has no field \"%s\"",
  									rec->refname, recfield->fieldname)));
  				*typeid = SPI_gettypeid(rec->tupdesc, fno);
  				if (fno > 0)
  					*typmod = rec->tupdesc->attrs[fno - 1]->atttypmod;
  				else
  					*typmod = -1;
  				if (fno > 0)
  					*collation = rec->tupdesc->attrs[fno - 1]->attcollation;
  				else	/* no system column types have collation */
  					*collation = InvalidOid;
  				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.  Also see notes in exec_eval_simple_expr
   * about allocation of the parameter array.)
   * ----------
   */
  static int
  exec_eval_integer(PLpgSQL_execstate *estate,
  				  PLpgSQL_expr *expr,
  				  bool *isNull)
  {
  	Datum		exprdatum;
  	Oid			exprtypeid;
  
  	exprdatum = exec_eval_expr(estate, expr, isNull, &exprtypeid);
  	exprdatum = exec_simple_cast_value(estate, exprdatum, exprtypeid,
  									   INT4OID, -1,
  									   *isNull);
  	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;
  
  	exprdatum = exec_eval_expr(estate, expr, isNull, &exprtypeid);
  	exprdatum = exec_simple_cast_value(estate, exprdatum, exprtypeid,
  									   BOOLOID, -1,
  									   *isNull);
  	return DatumGetBool(exprdatum);
  }
  
  /* ----------
   * exec_eval_expr			Evaluate an expression and return
   *					the result Datum.
   *
   * 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)
  {
  	Datum		result = 0;
  	int			rc;
  
  	/*
  	 * If first time through, create a plan for this expression.
  	 */
  	if (expr->plan == NULL)
  		exec_prepare_plan(estate, expr, 0);
  
  	/*
  	 * If this is a simple expression, bypass SPI and use the executor
  	 * directly
  	 */
  	if (exec_eval_simple_expr(estate, expr, &result, isNull, rettype))
  		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.
  	 */
  	*rettype = SPI_gettypeid(estate->eval_tuptable->tupdesc, 1);
  
  	/*
  	 * 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 (expr->plan == NULL)
  		exec_prepare_plan(estate, expr, 0);
  
  	/*
  	 * Set up ParamListInfo (hook function and possibly data values)
  	 */
  	paramLI = setup_param_list(estate, expr);
  
  	/*
  	 * If a portal was requested, put the query 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));
  		if (paramLI)
  			pfree(paramLI);
  		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;
  	estate->eval_lastoid = SPI_lastoid;
  
  	if (paramLI)
  		pfree(paramLI);
  
  	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_rec *rec = NULL;
  	PLpgSQL_row *row = NULL;
  	SPITupleTable *tuptab;
  	bool		found = false;
  	int			rc = PLPGSQL_RC_OK;
  	int			n;
  
  	/*
  	 * Determine if we assign to a record or a row
  	 */
  	if (stmt->rec != NULL)
  		rec = (PLpgSQL_rec *) (estate->datums[stmt->rec->dno]);
  	else if (stmt->row != NULL)
  		row = (PLpgSQL_row *) (estate->datums[stmt->row->dno]);
  	else
  		elog(ERROR, "unsupported target");
  
  	/*
  	 * 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, rec, row, NULL, tuptab->tupdesc);
  		exec_eval_cleanup(estate);
  	}
  	else
  		found = true;			/* processed at least one tuple */
  
  	/*
  	 * Now do the loop
  	 */
  	while (n > 0)
  	{
  		int			i;
  
  		for (i = 0; i < n; i++)
  		{
  			/*
  			 * Assign the tuple to the target
  			 */
  			exec_move_row(estate, rec, row, tuptab->vals[i], tuptab->tupdesc);
  			exec_eval_cleanup(estate);
  
  			/*
  			 * Execute the statements
  			 */
  			rc = exec_stmts(estate, stmt->body);
  
  			if (rc != PLPGSQL_RC_OK)
  			{
  				if (rc == PLPGSQL_RC_EXIT)
  				{
  					if (estate->exitlabel == NULL)
  					{
  						/* unlabelled exit, so exit the current loop */
  						rc = PLPGSQL_RC_OK;
  					}
  					else if (stmt->label != NULL &&
  							 strcmp(stmt->label, estate->exitlabel) == 0)
  					{
  						/* label matches this loop, so exit loop */
  						estate->exitlabel = NULL;
  						rc = PLPGSQL_RC_OK;
  					}
  
  					/*
  					 * otherwise, we processed a labelled exit that does not
  					 * match the current statement's label, if any; return
  					 * RC_EXIT so that the EXIT continues to recurse upward.
  					 */
  				}
  				else if (rc == PLPGSQL_RC_CONTINUE)
  				{
  					if (estate->exitlabel == NULL)
  					{
  						/* unlabelled continue, so re-run the current loop */
  						rc = PLPGSQL_RC_OK;
  						continue;
  					}
  					else if (stmt->label != NULL &&
  							 strcmp(stmt->label, estate->exitlabel) == 0)
  					{
  						/* label matches this loop, so re-run loop */
  						estate->exitlabel = NULL;
  						rc = PLPGSQL_RC_OK;
  						continue;
  					}
  
  					/*
  					 * otherwise, we process a labelled continue that does not
  					 * match the current statement's label, if any; return
  					 * RC_CONTINUE so that the CONTINUE will propagate up the
  					 * stack.
  					 */
  				}
  
  				/*
  				 * We're aborting the loop.  Need a goto to get out of two
  				 * levels of loop...
  				 */
  				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 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 though unlikely for a simple expression to become non-simple
   * (consider for example redefining a trivial view).  We must handle that for
   * correctness; fortunately it's normally inexpensive to call
   * SPI_plan_get_cached_plan for a simple expression.  We do not consider the
   * other direction (non-simple expression becoming simple) because we'll still
   * give correct results if that happens, and it's unlikely to be worth the
   * cycles to check.
   *
   * Note: if pass-by-reference, the result is in the eval_econtext's
   * temporary memory context.  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)
  {
  	ExprContext *econtext = estate->eval_econtext;
  	LocalTransactionId curlxid = MyProc->lxid;
  	CachedPlan *cplan;
  	ParamListInfo paramLI;
  	PLpgSQL_expr *save_cur_expr;
  	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.)
  	 */
  	cplan = SPI_plan_get_cached_plan(expr->plan);
  
  	/*
  	 * 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 (cplan->generation != expr->expr_simple_generation)
  	{
  		/* It got replanned ... is it still simple? */
  		exec_simple_recheck_plan(expr, cplan);
  		if (expr->expr_simple_expr == NULL)
  		{
  			/* Ooops, release refcount and fail */
  			ReleaseCachedPlan(cplan, true);
  			return false;
  		}
  	}
  
  	/*
  	 * Pass back previously-determined result type.
  	 */
  	*rettype = expr->expr_simple_type;
  
  	/*
  	 * 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_simple_recheck_plan above.)
  	 */
  	if (expr->expr_simple_lxid != curlxid)
  	{
  		oldcontext = MemoryContextSwitchTo(estate->simple_eval_estate->es_query_cxt);
  		expr->expr_simple_state = ExecInitExpr(expr->expr_simple_expr, NULL);
  		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 advance the snapshot if we are in a non-read-only function.
  	 * Without this, stable functions within the expression would fail to see
  	 * updates made so far by our own function.
  	 */
  	SPI_push();
  
  	oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
  	if (!estate->readonly_func)
  	{
  		CommandCounterIncrement();
  		PushActiveSnapshot(GetTransactionSnapshot());
  	}
  
  	/*
  	 * Create the param list in econtext's temporary memory context. We won't
  	 * need to free it explicitly, since it will go away at the next reset of
  	 * that context.
  	 *
  	 * Just for paranoia's sake, save and restore the prior value of
  	 * estate->cur_expr, which setup_param_list() sets.
  	 */
  	save_cur_expr = estate->cur_expr;
  
  	paramLI = setup_param_list(estate, expr);
  	econtext->ecxt_param_list_info = paramLI;
  
  	/*
  	 * 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,
  						   NULL);
  
  	/* Assorted cleanup */
  	expr->expr_simple_in_use = false;
  
  	estate->cur_expr = save_cur_expr;
  
  	if (!estate->readonly_func)
  		PopActiveSnapshot();
  
  	MemoryContextSwitchTo(oldcontext);
  
  	SPI_pop();
  
  	/*
  	 * 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 fill in the values for any expression parameters that are plain
   * PLpgSQL_var datums; these are cheap and safe to evaluate, and by setting
   * them with PARAM_FLAG_CONST flags, we allow the planner to use those values
   * in custom plans.  However, parameters that are not plain PLpgSQL_vars
   * should not be evaluated here, because they could throw errors (for example
   * "no such record field") and we do not want that to happen in a part of
   * the expression that might never be evaluated at runtime.  To handle those
   * parameters, we set up a paramFetch hook for the executor to call when it
   * wants a not-presupplied value.
   *
   * The result is a locally palloc'd array that should be pfree'd after use;
   * but note it can be NULL.
   */
  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);
  
  	/*
  	 * Could we re-use these arrays instead of palloc'ing a new one each time?
  	 * However, we'd have to re-fill the array each time anyway, since new
  	 * values might have been assigned to the variables.
  	 */
  	if (!bms_is_empty(expr->paramnos))
  	{
  		int			dno;
  
  		paramLI = (ParamListInfo)
  			palloc0(offsetof(ParamListInfoData, params) +
  					estate->ndatums * sizeof(ParamExternData));
  		paramLI->paramFetch = plpgsql_param_fetch;
  		paramLI->paramFetchArg = (void *) estate;
  		paramLI->parserSetup = (ParserSetupHook) plpgsql_parser_setup;
  		paramLI->parserSetupArg = (void *) expr;
  		paramLI->numParams = estate->ndatums;
  
  		/* Instantiate values for "safe" parameters of the expression */
  		dno = -1;
  		while ((dno = bms_next_member(expr->paramnos, dno)) >= 0)
  		{
  			PLpgSQL_datum *datum = estate->datums[dno];
  
  			if (datum->dtype == PLPGSQL_DTYPE_VAR)
  			{
  				PLpgSQL_var *var = (PLpgSQL_var *) datum;
  				ParamExternData *prm = &paramLI->params[dno];
  
  				prm->value = var->value;
  				prm->isnull = var->isnull;
  				prm->pflags = PARAM_FLAG_CONST;
  				prm->ptype = var->datatype->typoid;
  			}
  		}
  
  		/*
  		 * Set up link to active expr where the hook functions can find it.
  		 * Callers must save and restore cur_expr if there is any chance that
  		 * they are interrupting an active use of parameters.
  		 */
  		estate->cur_expr = 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
   */
  static void
  plpgsql_param_fetch(ParamListInfo params, int paramid)
  {
  	int			dno;
  	PLpgSQL_execstate *estate;
  	PLpgSQL_expr *expr;
  	PLpgSQL_datum *datum;
  	ParamExternData *prm;
  	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 = estate->cur_expr;
  	Assert(params->numParams == estate->ndatums);
  
  	/*
  	 * Do nothing if asked for a value that's not supposed to be used by this
  	 * SQL expression.  This avoids unwanted evaluations when functions such
  	 * as copyParamList try to materialize all the values.
  	 */
  	if (!bms_is_member(dno, expr->paramnos))
  		return;
  
  	/* OK, evaluate the value and store into the appropriate paramlist slot */
  	datum = estate->datums[dno];
  	prm = &params->params[dno];
  	exec_eval_datum(estate, datum,
  					&prm->ptype, &prmtypmod,
  					&prm->value, &prm->isnull);
  }
  
  
  /* ----------
   * exec_move_row			Move one tuple's values into a record or row
   *
   * Since this uses exec_assign_value, caller should eventually call
   * exec_eval_cleanup to prevent long-term memory leaks.
   * ----------
   */
  static void
  exec_move_row(PLpgSQL_execstate *estate,
  			  PLpgSQL_rec *rec,
  			  PLpgSQL_row *row,
  			  HeapTuple tup, TupleDesc tupdesc)
  {
  	/*
  	 * Record is simple - just copy the tuple and its descriptor into the
  	 * record variable
  	 */
  	if (rec != NULL)
  	{
  		/*
  		 * Copy input first, just in case it is pointing at variable's value
  		 */
  		if (HeapTupleIsValid(tup))
  			tup = heap_copytuple(tup);
  		else if (tupdesc)
  		{
  			/* If we have a tupdesc but no data, form an all-nulls tuple */
  			bool	   *nulls;
  
  			nulls = (bool *) palloc(tupdesc->natts * sizeof(bool));
  			memset(nulls, true, tupdesc->natts * sizeof(bool));
  
  			tup = heap_form_tuple(tupdesc, NULL, nulls);
  
  			pfree(nulls);
  		}
  
  		if (tupdesc)
  			tupdesc = CreateTupleDescCopy(tupdesc);
  
  		/* Free the old value ... */
  		if (rec->freetup)
  		{
  			heap_freetuple(rec->tup);
  			rec->freetup = false;
  		}
  		if (rec->freetupdesc)
  		{
  			FreeTupleDesc(rec->tupdesc);
  			rec->freetupdesc = false;
  		}
  
  		/* ... and install the new */
  		if (HeapTupleIsValid(tup))
  		{
  			rec->tup = tup;
  			rec->freetup = true;
  		}
  		else
  			rec->tup = NULL;
  
  		if (tupdesc)
  		{
  			rec->tupdesc = tupdesc;
  			rec->freetupdesc = true;
  		}
  		else
  			rec->tupdesc = NULL;
  
  		return;
  	}
  
  	/*
  	 * Row is a bit more complicated in that we assign the individual
  	 * attributes of the tuple to the variables the row points to.
  	 *
  	 * NOTE: this code used to demand row->nfields ==
  	 * HeapTupleHeaderGetNatts(tup->t_data), but that's wrong.  The tuple
  	 * might have more fields than we expected if it's from an
  	 * inheritance-child table of the current table, or it might have fewer if
  	 * the table has had columns added by ALTER TABLE. Ignore extra columns
  	 * and assume NULL for missing columns, the same as heap_getattr would do.
  	 * We also have to skip over dropped columns in either the source or
  	 * destination.
  	 *
  	 * If we have no tuple data at all, we'll assign NULL to all columns of
  	 * the row variable.
  	 */
  	if (row != NULL)
  	{
  		int			td_natts = tupdesc ? tupdesc->natts : 0;
  		int			t_natts;
  		int			fnum;
  		int			anum;
  
  		if (HeapTupleIsValid(tup))
  			t_natts = HeapTupleHeaderGetNatts(tup->t_data);
  		else
  			t_natts = 0;
  
  		anum = 0;
  		for (fnum = 0; fnum < row->nfields; fnum++)
  		{
  			PLpgSQL_var *var;
  			Datum		value;
  			bool		isnull;
  			Oid			valtype;
  
  			if (row->varnos[fnum] < 0)
  				continue;		/* skip dropped column in row struct */
  
  			var = (PLpgSQL_var *) (estate->datums[row->varnos[fnum]]);
  
  			while (anum < td_natts && tupdesc->attrs[anum]->attisdropped)
  				anum++;			/* skip dropped column in tuple */
  
  			if (anum < td_natts)
  			{
  				if (anum < t_natts)
  					value = SPI_getbinval(tup, tupdesc, anum + 1, &isnull);
  				else
  				{
  					value = (Datum) 0;
  					isnull = true;
  				}
  				valtype = SPI_gettypeid(tupdesc, anum + 1);
  				anum++;
  			}
  			else
  			{
  				value = (Datum) 0;
  				isnull = true;
  
  				/*
  				 * InvalidOid is OK because exec_assign_value doesn't care
  				 * about the type of a source NULL
  				 */
  				valtype = InvalidOid;
  			}
  
  			exec_assign_value(estate, (PLpgSQL_datum *) var,
  							  value, valtype, &isnull);
  		}
  
  		return;
  	}
  
  	elog(ERROR, "unsupported target");
  }
  
  /* ----------
   * 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
   * ----------
   */
  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 *) palloc0(natts * sizeof(Datum));
  	nulls = (bool *) palloc(natts * sizeof(bool));
  
  	for (i = 0; i < natts; i++)
  	{
  		Oid			fieldtypeid;
  		int32		fieldtypmod;
  
  		if (tupdesc->attrs[i]->attisdropped)
  		{
  			nulls[i] = true;	/* leave the column as null */
  			continue;
  		}
  		if (row->varnos[i] < 0) /* should not happen */
  			elog(ERROR, "dropped rowtype entry for non-dropped column");
  
  		exec_eval_datum(estate, estate->datums[row->varnos[i]],
  						&fieldtypeid, &fieldtypmod,
  						&dvalues[i], &nulls[i]);
  		if (fieldtypeid != tupdesc->attrs[i]->atttypid)
  			return NULL;
  		/* XXX should we insist on typmod match, too? */
  	}
  
  	tuple = heap_form_tuple(tupdesc, dvalues, nulls);
  
  	pfree(dvalues);
  	pfree(nulls);
  
  	return tuple;
  }
  
  /* ----------
   * get_tuple_from_datum		extract a tuple from a composite Datum
   *
   * Returns a freshly palloc'd HeapTuple.
   *
   * Note: it's caller's responsibility to be sure value is of composite type.
   * ----------
   */
  static HeapTuple
  get_tuple_from_datum(Datum value)
  {
  	HeapTupleHeader td = DatumGetHeapTupleHeader(value);
  	HeapTupleData tmptup;
  
  	/* Build a temporary HeapTuple control structure */
  	tmptup.t_len = HeapTupleHeaderGetDatumLength(td);
  	ItemPointerSetInvalid(&(tmptup.t_self));
  	tmptup.t_tableOid = InvalidOid;
  	tmptup.t_data = td;
  
  	/* Build a copy and return it */
  	return heap_copytuple(&tmptup);
  }
  
  /* ----------
   * get_tupdesc_from_datum	get a tuple descriptor for a composite Datum
   *
   * Returns a pointer to the TupleDesc of the tuple'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.
   * ----------
   */
  static TupleDesc
  get_tupdesc_from_datum(Datum value)
  {
  	HeapTupleHeader td = DatumGetHeapTupleHeader(value);
  	Oid			tupType;
  	int32		tupTypmod;
  
  	/* 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 get_tuple_from_datum() followed by exec_move_row(),
   * but we avoid constructing an intermediate physical copy of the tuple.
   * ----------
   */
  static void
  exec_move_row_from_datum(PLpgSQL_execstate *estate,
  						 PLpgSQL_rec *rec,
  						 PLpgSQL_row *row,
  						 Datum value)
  {
  	HeapTupleHeader td = DatumGetHeapTupleHeader(value);
  	Oid			tupType;
  	int32		tupTypmod;
  	TupleDesc	tupdesc;
  	HeapTupleData tmptup;
  
  	/* Extract rowtype info and find a tupdesc */
  	tupType = HeapTupleHeaderGetTypeId(td);
  	tupTypmod = HeapTupleHeaderGetTypMod(td);
  	tupdesc = lookup_rowtype_tupdesc(tupType, tupTypmod);
  
  	/* Build a temporary HeapTuple control structure */
  	tmptup.t_len = HeapTupleHeaderGetDatumLength(td);
  	ItemPointerSetInvalid(&(tmptup.t_self));
  	tmptup.t_tableOid = InvalidOid;
  	tmptup.t_data = td;
  
  	/* Do the move */
  	exec_move_row(estate, rec, row, &tmptup, tupdesc);
  
  	/* Release tupdesc usage count */
  	ReleaseTupleDesc(tupdesc);
  }
  
  /* ----------
   * convert_value_to_string			Convert a non-null Datum to C string
   *
   * Note: the result is in the estate's eval_econtext, 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.
   * ----------
   */
  static char *
  convert_value_to_string(PLpgSQL_execstate *estate, Datum value, Oid valtype)
  {
  	char	   *result;
  	MemoryContext oldcontext;
  	Oid			typoutput;
  	bool		typIsVarlena;
  
  	oldcontext = MemoryContextSwitchTo(estate->eval_econtext->ecxt_per_tuple_memory);
  	getTypeOutputInfo(valtype, &typoutput, &typIsVarlena);
  	result = OidOutputFunctionCall(typoutput, value);
  	MemoryContextSwitchTo(oldcontext);
  
  	return result;
  }
  
  /* ----------
   * exec_cast_value			Cast a value if required
   *
   * Note: the estate's eval_econtext 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, Oid valtype,
  				Oid reqtype,
  				FmgrInfo *reqinput,
  				Oid reqtypioparam,
  				int32 reqtypmod,
  				bool isnull)
  {
  	/*
  	 * If the type of the given value isn't what's requested, convert it.
  	 */
  	if (valtype != reqtype || reqtypmod != -1)
  	{
  		MemoryContext oldcontext;
  
  		oldcontext = MemoryContextSwitchTo(estate->eval_econtext->ecxt_per_tuple_memory);
  		if (!isnull)
  		{
  			char	   *extval;
  
  			extval = convert_value_to_string(estate, value, valtype);
  			value = InputFunctionCall(reqinput, extval,
  									  reqtypioparam, reqtypmod);
  		}
  		else
  		{
  			value = InputFunctionCall(reqinput, NULL,
  									  reqtypioparam, reqtypmod);
  		}
  		MemoryContextSwitchTo(oldcontext);
  	}
  
  	return value;
  }
  
  /* ----------
   * exec_simple_cast_value			Cast a value if required
   *
   * As above, but need not supply details about target type.  Note that this
   * is slower than exec_cast_value with cached type info, and so should be
   * avoided in heavily used code paths.
   * ----------
   */
  static Datum
  exec_simple_cast_value(PLpgSQL_execstate *estate,
  					   Datum value, Oid valtype,
  					   Oid reqtype, int32 reqtypmod,
  					   bool isnull)
  {
  	if (valtype != reqtype || reqtypmod != -1)
  	{
  		Oid			typinput;
  		Oid			typioparam;
  		FmgrInfo	finfo_input;
  
  		getTypeInputInfo(reqtype, &typinput, &typioparam);
  
  		fmgr_info(typinput, &finfo_input);
  
  		value = exec_cast_value(estate,
  								value,
  								valtype,
  								reqtype,
  								&finfo_input,
  								typioparam,
  								reqtypmod,
  								isnull);
  	}
  
  	return value;
  }
  
  
  /* ----------
   * exec_simple_check_node -		Recursively check if an expression
   *								is made only of simple things we can
   *								hand out directly to ExecEvalExpr()
   *								instead of calling SPI.
   * ----------
   */
  static bool
  exec_simple_check_node(Node *node)
  {
  	if (node == NULL)
  		return TRUE;
  
  	switch (nodeTag(node))
  	{
  		case T_Const:
  			return TRUE;
  
  		case T_Param:
  			return TRUE;
  
  		case T_ArrayRef:
  			{
  				ArrayRef   *expr = (ArrayRef *) node;
  
  				if (!exec_simple_check_node((Node *) expr->refupperindexpr))
  					return FALSE;
  				if (!exec_simple_check_node((Node *) expr->reflowerindexpr))
  					return FALSE;
  				if (!exec_simple_check_node((Node *) expr->refexpr))
  					return FALSE;
  				if (!exec_simple_check_node((Node *) expr->refassgnexpr))
  					return FALSE;
  
  				return TRUE;
  			}
  
  		case T_FuncExpr:
  			{
  				FuncExpr   *expr = (FuncExpr *) node;
  
  				if (expr->funcretset)
  					return FALSE;
  				if (!exec_simple_check_node((Node *) expr->args))
  					return FALSE;
  
  				return TRUE;
  			}
  
  		case T_OpExpr:
  			{
  				OpExpr	   *expr = (OpExpr *) node;
  
  				if (expr->opretset)
  					return FALSE;
  				if (!exec_simple_check_node((Node *) expr->args))
  					return FALSE;
  
  				return TRUE;
  			}
  
  		case T_DistinctExpr:
  			{
  				DistinctExpr *expr = (DistinctExpr *) node;
  
  				if (expr->opretset)
  					return FALSE;
  				if (!exec_simple_check_node((Node *) expr->args))
  					return FALSE;
  
  				return TRUE;
  			}
  
  		case T_NullIfExpr:
  			{
  				NullIfExpr *expr = (NullIfExpr *) node;
  
  				if (expr->opretset)
  					return FALSE;
  				if (!exec_simple_check_node((Node *) expr->args))
  					return FALSE;
  
  				return TRUE;
  			}
  
  		case T_ScalarArrayOpExpr:
  			{
  				ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;
  
  				if (!exec_simple_check_node((Node *) expr->args))
  					return FALSE;
  
  				return TRUE;
  			}
  
  		case T_BoolExpr:
  			{
  				BoolExpr   *expr = (BoolExpr *) node;
  
  				if (!exec_simple_check_node((Node *) expr->args))
  					return FALSE;
  
  				return TRUE;
  			}
  
  		case T_FieldSelect:
  			return exec_simple_check_node((Node *) ((FieldSelect *) node)->arg);
  
  		case T_FieldStore:
  			{
  				FieldStore *expr = (FieldStore *) node;
  
  				if (!exec_simple_check_node((Node *) expr->arg))
  					return FALSE;
  				if (!exec_simple_check_node((Node *) expr->newvals))
  					return FALSE;
  
  				return TRUE;
  			}
  
  		case T_RelabelType:
  			return exec_simple_check_node((Node *) ((RelabelType *) node)->arg);
  
  		case T_CoerceViaIO:
  			return exec_simple_check_node((Node *) ((CoerceViaIO *) node)->arg);
  
  		case T_ArrayCoerceExpr:
  			return exec_simple_check_node((Node *) ((ArrayCoerceExpr *) node)->arg);
  
  		case T_ConvertRowtypeExpr:
  			return exec_simple_check_node((Node *) ((ConvertRowtypeExpr *) node)->arg);
  
  		case T_CaseExpr:
  			{
  				CaseExpr   *expr = (CaseExpr *) node;
  
  				if (!exec_simple_check_node((Node *) expr->arg))
  					return FALSE;
  				if (!exec_simple_check_node((Node *) expr->args))
  					return FALSE;
  				if (!exec_simple_check_node((Node *) expr->defresult))
  					return FALSE;
  
  				return TRUE;
  			}
  
  		case T_CaseWhen:
  			{
  				CaseWhen   *when = (CaseWhen *) node;
  
  				if (!exec_simple_check_node((Node *) when->expr))
  					return FALSE;
  				if (!exec_simple_check_node((Node *) when->result))
  					return FALSE;
  
  				return TRUE;
  			}
  
  		case T_CaseTestExpr:
  			return TRUE;
  
  		case T_ArrayExpr:
  			{
  				ArrayExpr  *expr = (ArrayExpr *) node;
  
  				if (!exec_simple_check_node((Node *) expr->elements))
  					return FALSE;
  
  				return TRUE;
  			}
  
  		case T_RowExpr:
  			{
  				RowExpr    *expr = (RowExpr *) node;
  
  				if (!exec_simple_check_node((Node *) expr->args))
  					return FALSE;
  
  				return TRUE;
  			}
  
  		case T_RowCompareExpr:
  			{
  				RowCompareExpr *expr = (RowCompareExpr *) node;
  
  				if (!exec_simple_check_node((Node *) expr->largs))
  					return FALSE;
  				if (!exec_simple_check_node((Node *) expr->rargs))
  					return FALSE;
  
  				return TRUE;
  			}
  
  		case T_CoalesceExpr:
  			{
  				CoalesceExpr *expr = (CoalesceExpr *) node;
  
  				if (!exec_simple_check_node((Node *) expr->args))
  					return FALSE;
  
  				return TRUE;
  			}
  
  		case T_MinMaxExpr:
  			{
  				MinMaxExpr *expr = (MinMaxExpr *) node;
  
  				if (!exec_simple_check_node((Node *) expr->args))
  					return FALSE;
  
  				return TRUE;
  			}
  
  		case T_XmlExpr:
  			{
  				XmlExpr    *expr = (XmlExpr *) node;
  
  				if (!exec_simple_check_node((Node *) expr->named_args))
  					return FALSE;
  				if (!exec_simple_check_node((Node *) expr->args))
  					return FALSE;
  
  				return TRUE;
  			}
  
  		case T_NullTest:
  			return exec_simple_check_node((Node *) ((NullTest *) node)->arg);
  
  		case T_BooleanTest:
  			return exec_simple_check_node((Node *) ((BooleanTest *) node)->arg);
  
  		case T_CoerceToDomain:
  			return exec_simple_check_node((Node *) ((CoerceToDomain *) node)->arg);
  
  		case T_CoerceToDomainValue:
  			return TRUE;
  
  		case T_List:
  			{
  				List	   *expr = (List *) node;
  				ListCell   *l;
  
  				foreach(l, expr)
  				{
  					if (!exec_simple_check_node(lfirst(l)))
  						return FALSE;
  				}
  
  				return TRUE;
  			}
  
  		default:
  			return FALSE;
  	}
  }
  
  
  /* ----------
   * 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_expr *expr)
  {
  	List	   *plansources;
  	CachedPlanSource *plansource;
  	Query	   *query;
  	CachedPlan *cplan;
  
  	/*
  	 * Initialize to "not simple", and remember the plan generation number we
  	 * last checked.  (If we don't get as far as obtaining a plan to check, we
  	 * just leave expr_simple_generation set to 0.)
  	 */
  	expr->expr_simple_expr = NULL;
  	expr->expr_simple_generation = 0;
  
  	/*
  	 * 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);
  
  	/*
  	 * Do some checking on the analyzed-and-rewritten form of the query. These
  	 * checks are basically redundant with the tests in
  	 * exec_simple_recheck_plan, but the point is to avoid building a plan if
  	 * possible.  Since this function is only called immediately after
  	 * creating the CachedPlanSource, we need not worry about the query being
  	 * stale.
  	 */
  
  	/*
  	 * 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
  	 */
  	if (query->hasAggs ||
  		query->hasWindowFuncs ||
  		query->hasSubLinks ||
  		query->hasForUpdate ||
  		query->cteList ||
  		query->jointree->quals ||
  		query->groupClause ||
  		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, it seems worth constructing a plan for more careful checking.
  	 */
  
  	/* Get the generic plan for the query */
  	cplan = SPI_plan_get_cached_plan(expr->plan);
  
  	/* Can't fail, because we checked for a single CachedPlanSource above */
  	Assert(cplan != NULL);
  
  	/* Share the remaining work with recheck code path */
  	exec_simple_recheck_plan(expr, cplan);
  
  	/* Release our plan refcount */
  	ReleaseCachedPlan(cplan, true);
  }
  
  /*
   * exec_simple_recheck_plan --- check for simple plan once we have CachedPlan
   */
  static void
  exec_simple_recheck_plan(PLpgSQL_expr *expr, CachedPlan *cplan)
  {
  	PlannedStmt *stmt;
  	Plan	   *plan;
  	TargetEntry *tle;
  
  	/*
  	 * Initialize to "not simple", and remember the plan generation number we
  	 * last checked.
  	 */
  	expr->expr_simple_expr = NULL;
  	expr->expr_simple_generation = cplan->generation;
  
  	/*
  	 * 1. There must be one single plantree
  	 */
  	if (list_length(cplan->stmt_list) != 1)
  		return;
  	stmt = (PlannedStmt *) linitial(cplan->stmt_list);
  
  	/*
  	 * 2. It must be a RESULT plan --> no scan's required
  	 */
  	if (!IsA(stmt, PlannedStmt))
  		return;
  	if (stmt->commandType != CMD_SELECT)
  		return;
  	plan = stmt->planTree;
  	if (!IsA(plan, Result))
  		return;
  
  	/*
  	 * 3. Can't have any subplan or qual clause, either
  	 */
  	if (plan->lefttree != NULL ||
  		plan->righttree != NULL ||
  		plan->initPlan != NULL ||
  		plan->qual != NULL ||
  		((Result *) plan)->resconstantqual != NULL)
  		return;
  
  	/*
  	 * 4. The plan must have a single attribute as result
  	 */
  	if (list_length(plan->targetlist) != 1)
  		return;
  
  	tle = (TargetEntry *) linitial(plan->targetlist);
  
  	/*
  	 * 5. Check that all the nodes in the expression are non-scary.
  	 */
  	if (!exec_simple_check_node((Node *) tle->expr))
  		return;
  
  	/*
  	 * Yes - this is a simple expression.  Mark it as such, and initialize
  	 * state to "not valid in current transaction".
  	 */
  	expr->expr_simple_expr = tle->expr;
  	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);
  }
  
  /* ----------
   * 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]);
  	var->value = BoolGetDatum(state);
  	var->isnull = 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;
  
  		Assert(shared_simple_eval_estate == NULL);
  		oldcontext = MemoryContextSwitchTo(TopTransactionContext);
  		shared_simple_eval_estate = CreateExecutorState();
  		estate->simple_eval_estate = shared_simple_eval_estate;
  		MemoryContextSwitchTo(oldcontext);
  	}
  
  	/*
  	 * 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)
  	{
  		/* Shouldn't be any econtext stack entries left at commit */
  		Assert(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;
  		}
  	}
  }
  
  /*
   * free_var --- pfree any pass-by-reference value of the variable.
   *
   * This should always be followed by some assignment to var->value,
   * as it leaves a dangling pointer.
   */
  static void
  free_var(PLpgSQL_var *var)
  {
  	if (var->freeval)
  	{
  		pfree(DatumGetPointer(var->value));
  		var->freeval = false;
  	}
  }
  
  /*
   * free old value of a text variable and assign new value from C string
   */
  static void
  assign_text_var(PLpgSQL_var *var, const char *str)
  {
  	free_var(var);
  	var->value = CStringGetTextDatum(str);
  	var->isnull = false;
  	var->freeval = true;
  }
  
  /*
   * exec_eval_using_params --- evaluate params of USING clause
   */
  static PreparedParamsData *
  exec_eval_using_params(PLpgSQL_execstate *estate, List *params)
  {
  	PreparedParamsData *ppd;
  	int			nargs;
  	int			i;
  	ListCell   *lc;
  
  	ppd = (PreparedParamsData *) palloc(sizeof(PreparedParamsData));
  	nargs = list_length(params);
  
  	ppd->nargs = nargs;
  	ppd->types = (Oid *) palloc(nargs * sizeof(Oid));
  	ppd->values = (Datum *) palloc(nargs * sizeof(Datum));
  	ppd->nulls = (char *) palloc(nargs * sizeof(char));
  	ppd->freevals = (bool *) palloc(nargs * sizeof(bool));
  
  	i = 0;
  	foreach(lc, params)
  	{
  		PLpgSQL_expr *param = (PLpgSQL_expr *) lfirst(lc);
  		bool		isnull;
  
  		ppd->values[i] = exec_eval_expr(estate, param,
  										&isnull,
  										&ppd->types[i]);
  		ppd->nulls[i] = isnull ? 'n' : ' ';
  		ppd->freevals[i] = false;
  
  		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]));
  				ppd->freevals[i] = true;
  			}
  		}
  		/* pass-by-ref non null values must be copied into plpgsql context */
  		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);
  				ppd->freevals[i] = true;
  			}
  		}
  
  		exec_eval_cleanup(estate);
  
  		i++;
  	}
  
  	return ppd;
  }
  
  /*
   * free_params_data --- pfree all pass-by-reference values used in USING clause
   */
  static void
  free_params_data(PreparedParamsData *ppd)
  {
  	int			i;
  
  	for (i = 0; i < ppd->nargs; i++)
  	{
  		if (ppd->freevals[i])
  			pfree(DatumGetPointer(ppd->values[i]));
  	}
  
  	pfree(ppd->types);
  	pfree(ppd->values);
  	pfree(ppd->nulls);
  	pfree(ppd->freevals);
  
  	pfree(ppd);
  }
  
  /*
   * Open portal for dynamic query
   */
  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;
  	char	   *querystr;
  
  	/*
  	 * 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);
  	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 out of the temporary context before we clean up */
  	querystr = pstrdup(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);
  		free_params_data(ppd);
  	}
  	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));
  	pfree(querystr);
  
  	return portal;
  }
  
  /*
   * Return a formatted string with information about an expression's parameters,
   * or NULL if the expression does not take any parameters.
   */
  static char *
  format_expr_params(PLpgSQL_execstate *estate,
  				   const PLpgSQL_expr *expr)
  {
  	int			paramno;
  	int			dno;
  	StringInfoData paramstr;
  
  	if (!expr->paramnos)
  		return NULL;
  
  	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
  		{
  			char	   *value = convert_value_to_string(estate, paramdatum, paramtypeid);
  			char	   *p;
  
  			appendStringInfoCharMacro(&paramstr, '\'');
  			for (p = value; *p; p++)
  			{
  				if (*p == '\'') /* double single quotes */
  					appendStringInfoCharMacro(&paramstr, *p);
  				appendStringInfoCharMacro(&paramstr, *p);
  			}
  			appendStringInfoCharMacro(&paramstr, '\'');
  		}
  
  		paramno++;
  	}
  
  	return paramstr.data;
  }
  
  /*
   * Return a formatted string with information about PreparedParamsData, or NULL
   * if there are no parameters.
   */
  static char *
  format_preparedparamsdata(PLpgSQL_execstate *estate,
  						  const PreparedParamsData *ppd)
  {
  	int			paramno;
  	StringInfoData paramstr;
  
  	if (!ppd)
  		return NULL;
  
  	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
  		{
  			char	   *value = convert_value_to_string(estate, ppd->values[paramno], ppd->types[paramno]);
  			char	   *p;
  
  			appendStringInfoCharMacro(&paramstr, '\'');
  			for (p = value; *p; p++)
  			{
  				if (*p == '\'') /* double single quotes */
  					appendStringInfoCharMacro(&paramstr, *p);
  				appendStringInfoCharMacro(&paramstr, *p);
  			}
  			appendStringInfoCharMacro(&paramstr, '\'');
  		}
  	}
  
  	return paramstr.data;
  }
  