text: /*-------------------------------------------------------------------------
   *
   * parse_utilcmd.c
   *	  Perform parse analysis work for various utility commands
   *
   * Formerly we did this work during parse_analyze() in analyze.c.  However
   * that is fairly unsafe in the presence of querytree caching, since any
   * database state that we depend on in making the transformations might be
   * obsolete by the time the utility command is executed; and utility commands
   * have no infrastructure for holding locks or rechecking plan validity.
   * Hence these functions are now called at the start of execution of their
   * respective utility commands.
   *
   * NOTE: in general we must avoid scribbling on the passed-in raw parse
   * tree, since it might be in a plan cache.  The simplest solution is
   * a quick copyObject() call before manipulating the query tree.
   *
   *
   * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   *	src/backend/parser/parse_utilcmd.c
   *
   *-------------------------------------------------------------------------
   */
  
  #include "postgres.h"
  
  #include "access/amapi.h"
  #include "access/htup_details.h"
  #include "access/relation.h"
  #include "access/reloptions.h"
  #include "access/table.h"
  #include "catalog/dependency.h"
  #include "catalog/heap.h"
  #include "catalog/index.h"
  #include "catalog/namespace.h"
  #include "catalog/pg_am.h"
  #include "catalog/pg_collation.h"
  #include "catalog/pg_constraint.h"
  #include "catalog/pg_opclass.h"
  #include "catalog/pg_operator.h"
  #include "catalog/pg_statistic_ext.h"
  #include "catalog/pg_type.h"
  #include "commands/comment.h"
  #include "commands/defrem.h"
  #include "commands/sequence.h"
  #include "commands/tablecmds.h"
  #include "commands/tablespace.h"
  #include "miscadmin.h"
  #include "nodes/makefuncs.h"
  #include "nodes/nodeFuncs.h"
  #include "optimizer/optimizer.h"
  #include "parser/analyze.h"
  #include "parser/parse_clause.h"
  #include "parser/parse_coerce.h"
  #include "parser/parse_collate.h"
  #include "parser/parse_expr.h"
  #include "parser/parse_relation.h"
  #include "parser/parse_target.h"
  #include "parser/parse_type.h"
  #include "parser/parse_utilcmd.h"
  #include "parser/parser.h"
  #include "rewrite/rewriteManip.h"
  #include "utils/acl.h"
  #include "utils/builtins.h"
  #include "utils/lsyscache.h"
  #include "utils/partcache.h"
  #include "utils/rel.h"
  #include "utils/ruleutils.h"
  #include "utils/syscache.h"
  #include "utils/typcache.h"
  
  
  /* State shared by transformCreateStmt and its subroutines */
  typedef struct
  {
  	ParseState *pstate;			/* overall parser state */
  	const char *stmtType;		/* "CREATE [FOREIGN] TABLE" or "ALTER TABLE" */
  	RangeVar   *relation;		/* relation to create */
  	Relation	rel;			/* opened/locked rel, if ALTER */
  	List	   *inhRelations;	/* relations to inherit from */
  	bool		isforeign;		/* true if CREATE/ALTER FOREIGN TABLE */
  	bool		isalter;		/* true if altering existing table */
  	List	   *columns;		/* ColumnDef items */
  	List	   *ckconstraints;	/* CHECK constraints */
  	List	   *fkconstraints;	/* FOREIGN KEY constraints */
  	List	   *ixconstraints;	/* index-creating constraints */
  	List	   *inh_indexes;	/* cloned indexes from INCLUDING INDEXES */
  	List	   *extstats;		/* cloned extended statistics */
  	List	   *blist;			/* "before list" of things to do before
  								 * creating the table */
  	List	   *alist;			/* "after list" of things to do after creating
  								 * the table */
  	IndexStmt  *pkey;			/* PRIMARY KEY index, if any */
  	bool		ispartitioned;	/* true if table is partitioned */
  	PartitionBoundSpec *partbound;	/* transformed FOR VALUES */
  	bool		ofType;			/* true if statement contains OF typename */
  } CreateStmtContext;
  
  /* State shared by transformCreateSchemaStmt and its subroutines */
  typedef struct
  {
  	const char *stmtType;		/* "CREATE SCHEMA" or "ALTER SCHEMA" */
  	char	   *schemaname;		/* name of schema */
  	RoleSpec   *authrole;		/* owner of schema */
  	List	   *sequences;		/* CREATE SEQUENCE items */
  	List	   *tables;			/* CREATE TABLE items */
  	List	   *views;			/* CREATE VIEW items */
  	List	   *indexes;		/* CREATE INDEX items */
  	List	   *triggers;		/* CREATE TRIGGER items */
  	List	   *grants;			/* GRANT items */
  } CreateSchemaStmtContext;
  
  
  static void transformColumnDefinition(CreateStmtContext *cxt,
  									  ColumnDef *column);
  static void transformTableConstraint(CreateStmtContext *cxt,
  									 Constraint *constraint);
  static void transformTableLikeClause(CreateStmtContext *cxt,
  									 TableLikeClause *table_like_clause);
  static void transformOfType(CreateStmtContext *cxt,
  							TypeName *ofTypename);
  static CreateStatsStmt *generateClonedExtStatsStmt(RangeVar *heapRel,
  												   Oid heapRelid, Oid source_statsid);
  static List *get_collation(Oid collation, Oid actual_datatype);
  static List *get_opclass(Oid opclass, Oid actual_datatype);
  static void transformIndexConstraints(CreateStmtContext *cxt);
  static IndexStmt *transformIndexConstraint(Constraint *constraint,
  										   CreateStmtContext *cxt);
  static void transformExtendedStatistics(CreateStmtContext *cxt);
  static void transformFKConstraints(CreateStmtContext *cxt,
  								   bool skipValidation,
  								   bool isAddConstraint);
  static void transformCheckConstraints(CreateStmtContext *cxt,
  									  bool skipValidation);
  static void transformConstraintAttrs(CreateStmtContext *cxt,
  									 List *constraintList);
  static void transformColumnType(CreateStmtContext *cxt, ColumnDef *column);
  static void setSchemaName(char *context_schema, char **stmt_schema_name);
  static void transformPartitionCmd(CreateStmtContext *cxt, PartitionCmd *cmd);
  static List *transformPartitionRangeBounds(ParseState *pstate, List *blist,
  										   Relation parent);
  static void validateInfiniteBounds(ParseState *pstate, List *blist);
  static Const *transformPartitionBoundValue(ParseState *pstate, Node *con,
  										   const char *colName, Oid colType, int32 colTypmod,
  										   Oid partCollation);
  
  
  /*
   * transformCreateStmt -
   *	  parse analysis for CREATE TABLE
   *
   * Returns a List of utility commands to be done in sequence.  One of these
   * will be the transformed CreateStmt, but there may be additional actions
   * to be done before and after the actual DefineRelation() call.
   *
   * SQL allows constraints to be scattered all over, so thumb through
   * the columns and collect all constraints into one place.
   * If there are any implied indices (e.g. UNIQUE or PRIMARY KEY)
   * then expand those into multiple IndexStmt blocks.
   *	  - thomas 1997-12-02
   */
  List *
  transformCreateStmt(CreateStmt *stmt, const char *queryString)
  {
  	ParseState *pstate;
  	CreateStmtContext cxt;
  	List	   *result;
  	List	   *save_alist;
  	ListCell   *elements;
  	Oid			namespaceid;
  	Oid			existing_relid;
  	ParseCallbackState pcbstate;
  	bool		is_foreign_table = IsA(stmt, CreateForeignTableStmt);
  
  	/*
  	 * We must not scribble on the passed-in CreateStmt, so copy it.  (This is
  	 * overkill, but easy.)
  	 */
  	stmt = copyObject(stmt);
  
  	/* Set up pstate */
  	pstate = make_parsestate(NULL);
  	pstate->p_sourcetext = queryString;
  
  	/*
  	 * Look up the creation namespace.  This also checks permissions on the
  	 * target namespace, locks it against concurrent drops, checks for a
  	 * preexisting relation in that namespace with the same name, and updates
  	 * stmt->relation->relpersistence if the selected namespace is temporary.
  	 */
  	setup_parser_errposition_callback(&pcbstate, pstate,
  									  stmt->relation->location);
  	namespaceid =
  		RangeVarGetAndCheckCreationNamespace(stmt->relation, NoLock,
  											 &existing_relid);
  	cancel_parser_errposition_callback(&pcbstate);
  
  	/*
  	 * If the relation already exists and the user specified "IF NOT EXISTS",
  	 * bail out with a NOTICE.
  	 */
  	if (stmt->if_not_exists && OidIsValid(existing_relid))
  	{
  		ereport(NOTICE,
  				(errcode(ERRCODE_DUPLICATE_TABLE),
  				 errmsg("relation \"%s\" already exists, skipping",
  						stmt->relation->relname)));
  		return NIL;
  	}
  
  	/*
  	 * If the target relation name isn't schema-qualified, make it so.  This
  	 * prevents some corner cases in which added-on rewritten commands might
  	 * think they should apply to other relations that have the same name and
  	 * are earlier in the search path.  But a local temp table is effectively
  	 * specified to be in pg_temp, so no need for anything extra in that case.
  	 */
  	if (stmt->relation->schemaname == NULL
  		&& stmt->relation->relpersistence != RELPERSISTENCE_TEMP)
  		stmt->relation->schemaname = get_namespace_name(namespaceid);
  
  	/* Set up CreateStmtContext */
  	cxt.pstate = pstate;
  	if (IsA(stmt, CreateForeignTableStmt))
  	{
  		cxt.stmtType = "CREATE FOREIGN TABLE";
  		cxt.isforeign = true;
  	}
  	else
  	{
  		cxt.stmtType = "CREATE TABLE";
  		cxt.isforeign = false;
  	}
  	cxt.relation = stmt->relation;
  	cxt.rel = NULL;
  	cxt.inhRelations = stmt->inhRelations;
  	cxt.isalter = false;
  	cxt.columns = NIL;
  	cxt.ckconstraints = NIL;
  	cxt.fkconstraints = NIL;
  	cxt.ixconstraints = NIL;
  	cxt.inh_indexes = NIL;
  	cxt.extstats = NIL;
  	cxt.blist = NIL;
  	cxt.alist = NIL;
  	cxt.pkey = NULL;
  	cxt.ispartitioned = stmt->partspec != NULL;
  	cxt.partbound = stmt->partbound;
  	cxt.ofType = (stmt->ofTypename != NULL);
  
  	Assert(!stmt->ofTypename || !stmt->inhRelations);	/* grammar enforces */
  
  	if (stmt->ofTypename)
  		transformOfType(&cxt, stmt->ofTypename);
  
  	if (stmt->partspec)
  	{
  		if (stmt->inhRelations && !stmt->partbound)
  			ereport(ERROR,
  					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
  					 errmsg("cannot create partitioned table as inheritance child")));
  	}
  
  	/*
  	 * Run through each primary element in the table creation clause. Separate
  	 * column defs from constraints, and do preliminary analysis.
  	 */
  	foreach(elements, stmt->tableElts)
  	{
  		Node	   *element = lfirst(elements);
  
  		switch (nodeTag(element))
  		{
  			case T_ColumnDef:
  				transformColumnDefinition(&cxt, (ColumnDef *) element);
  				break;
  
  			case T_Constraint:
  				transformTableConstraint(&cxt, (Constraint *) element);
  				break;
  
  			case T_TableLikeClause:
  				transformTableLikeClause(&cxt, (TableLikeClause *) element);
  				break;
  
  			default:
  				elog(ERROR, "unrecognized node type: %d",
  					 (int) nodeTag(element));
  				break;
  		}
  	}
  
  	/*
  	 * Transfer anything we already have in cxt.alist into save_alist, to keep
  	 * it separate from the output of transformIndexConstraints.  (This may
  	 * not be necessary anymore, but we'll keep doing it to preserve the
  	 * historical order of execution of the alist commands.)
  	 */
  	save_alist = cxt.alist;
  	cxt.alist = NIL;
  
  	Assert(stmt->constraints == NIL);
  
  	/*
  	 * Postprocess constraints that give rise to index definitions.
  	 */
  	transformIndexConstraints(&cxt);
  
  	/*
  	 * Postprocess foreign-key constraints.
  	 */
  	transformFKConstraints(&cxt, true, false);
  
  	/*
  	 * Postprocess check constraints.
  	 */
  	transformCheckConstraints(&cxt, !is_foreign_table ? true : false);
  
  	/*
  	 * Postprocess extended statistics.
  	 */
  	transformExtendedStatistics(&cxt);
  
  	/*
  	 * Output results.
  	 */
  	stmt->tableElts = cxt.columns;
  	stmt->constraints = cxt.ckconstraints;
  
  	result = lappend(cxt.blist, stmt);
  	result = list_concat(result, cxt.alist);
  	result = list_concat(result, save_alist);
  
  	return result;
  }
  
  /*
   * generateSerialExtraStmts
   *		Generate CREATE SEQUENCE and ALTER SEQUENCE ... OWNED BY statements
   *		to create the sequence for a serial or identity column.
   *
   * This includes determining the name the sequence will have.  The caller
   * can ask to get back the name components by passing non-null pointers
   * for snamespace_p and sname_p.
   */
  static void
  generateSerialExtraStmts(CreateStmtContext *cxt, ColumnDef *column,
  						 Oid seqtypid, List *seqoptions, bool for_identity,
  						 char **snamespace_p, char **sname_p)
  {
  	ListCell   *option;
  	DefElem    *nameEl = NULL;
  	Oid			snamespaceid;
  	char	   *snamespace;
  	char	   *sname;
  	CreateSeqStmt *seqstmt;
  	AlterSeqStmt *altseqstmt;
  	List	   *attnamelist;
  
  	/*
  	 * Determine namespace and name to use for the sequence.
  	 *
  	 * First, check if a sequence name was passed in as an option.  This is
  	 * used by pg_dump.  Else, generate a name.
  	 *
  	 * Although we use ChooseRelationName, it's not guaranteed that the
  	 * selected sequence name won't conflict; given sufficiently long field
  	 * names, two different serial columns in the same table could be assigned
  	 * the same sequence name, and we'd not notice since we aren't creating
  	 * the sequence quite yet.  In practice this seems quite unlikely to be a
  	 * problem, especially since few people would need two serial columns in
  	 * one table.
  	 */
  	foreach(option, seqoptions)
  	{
  		DefElem    *defel = lfirst_node(DefElem, option);
  
  		if (strcmp(defel->defname, "sequence_name") == 0)
  		{
  			if (nameEl)
  				ereport(ERROR,
  						(errcode(ERRCODE_SYNTAX_ERROR),
  						 errmsg("conflicting or redundant options")));
  			nameEl = defel;
  		}
  	}
  
  	if (nameEl)
  	{
  		RangeVar   *rv = makeRangeVarFromNameList(castNode(List, nameEl->arg));
  
  		snamespace = rv->schemaname;
  		if (!snamespace)
  		{
  			/* Given unqualified SEQUENCE NAME, select namespace */
  			if (cxt->rel)
  				snamespaceid = RelationGetNamespace(cxt->rel);
  			else
  				snamespaceid = RangeVarGetCreationNamespace(cxt->relation);
  			snamespace = get_namespace_name(snamespaceid);
  		}
  		sname = rv->relname;
  		/* Remove the SEQUENCE NAME item from seqoptions */
  		seqoptions = list_delete_ptr(seqoptions, nameEl);
  	}
  	else
  	{
  		if (cxt->rel)
  			snamespaceid = RelationGetNamespace(cxt->rel);
  		else
  		{
  			snamespaceid = RangeVarGetCreationNamespace(cxt->relation);
  			RangeVarAdjustRelationPersistence(cxt->relation, snamespaceid);
  		}
  		snamespace = get_namespace_name(snamespaceid);
  		sname = ChooseRelationName(cxt->relation->relname,
  								   column->colname,
  								   "seq",
  								   snamespaceid,
  								   false);
  	}
  
  	ereport(DEBUG1,
  			(errmsg("%s will create implicit sequence \"%s\" for serial column \"%s.%s\"",
  					cxt->stmtType, sname,
  					cxt->relation->relname, column->colname)));
  
  	/*
  	 * Build a CREATE SEQUENCE command to create the sequence object, and add
  	 * it to the list of things to be done before this CREATE/ALTER TABLE.
  	 */
  	seqstmt = makeNode(CreateSeqStmt);
  	seqstmt->for_identity = for_identity;
  	seqstmt->sequence = makeRangeVar(snamespace, sname, -1);
  	seqstmt->options = seqoptions;
  
  	/*
  	 * If a sequence data type was specified, add it to the options.  Prepend
  	 * to the list rather than append; in case a user supplied their own AS
  	 * clause, the "redundant options" error will point to their occurrence,
  	 * not our synthetic one.
  	 */
  	if (seqtypid)
  		seqstmt->options = lcons(makeDefElem("as",
  											 (Node *) makeTypeNameFromOid(seqtypid, -1),
  											 -1),
  								 seqstmt->options);
  
  	/*
  	 * If this is ALTER ADD COLUMN, make sure the sequence will be owned by
  	 * the table's owner.  The current user might be someone else (perhaps a
  	 * superuser, or someone who's only a member of the owning role), but the
  	 * SEQUENCE OWNED BY mechanisms will bleat unless table and sequence have
  	 * exactly the same owning role.
  	 */
  	if (cxt->rel)
  		seqstmt->ownerId = cxt->rel->rd_rel->relowner;
  	else
  		seqstmt->ownerId = InvalidOid;
  
  	cxt->blist = lappend(cxt->blist, seqstmt);
  
  	/*
  	 * Store the identity sequence name that we decided on.  ALTER TABLE ...
  	 * ADD COLUMN ... IDENTITY needs this so that it can fill the new column
  	 * with values from the sequence, while the association of the sequence
  	 * with the table is not set until after the ALTER TABLE.
  	 */
  	column->identitySequence = seqstmt->sequence;
  
  	/*
  	 * Build an ALTER SEQUENCE ... OWNED BY command to mark the sequence as
  	 * owned by this column, and add it to the list of things to be done after
  	 * this CREATE/ALTER TABLE.
  	 */
  	altseqstmt = makeNode(AlterSeqStmt);
  	altseqstmt->sequence = makeRangeVar(snamespace, sname, -1);
  	attnamelist = list_make3(makeString(snamespace),
  							 makeString(cxt->relation->relname),
  							 makeString(column->colname));
  	altseqstmt->options = list_make1(makeDefElem("owned_by",
  												 (Node *) attnamelist, -1));
  	altseqstmt->for_identity = for_identity;
  
  	cxt->alist = lappend(cxt->alist, altseqstmt);
  
  	if (snamespace_p)
  		*snamespace_p = snamespace;
  	if (sname_p)
  		*sname_p = sname;
  }
  
  /*
   * transformColumnDefinition -
   *		transform a single ColumnDef within CREATE TABLE
   *		Also used in ALTER TABLE ADD COLUMN
   */
  static void
  transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
  {
  	bool		is_serial;
  	bool		saw_nullable;
  	bool		saw_default;
  	bool		saw_identity;
  	bool		saw_generated;
  	ListCell   *clist;
  
  	cxt->columns = lappend(cxt->columns, column);
  
  	/* Check for SERIAL pseudo-types */
  	is_serial = false;
  	if (column->typeName
  		&& list_length(column->typeName->names) == 1
  		&& !column->typeName->pct_type)
  	{
  		char	   *typname = strVal(linitial(column->typeName->names));
  
  		if (strcmp(typname, "smallserial") == 0 ||
  			strcmp(typname, "serial2") == 0)
  		{
  			is_serial = true;
  			column->typeName->names = NIL;
  			column->typeName->typeOid = INT2OID;
  		}
  		else if (strcmp(typname, "serial") == 0 ||
  				 strcmp(typname, "serial4") == 0)
  		{
  			is_serial = true;
  			column->typeName->names = NIL;
  			column->typeName->typeOid = INT4OID;
  		}
  		else if (strcmp(typname, "bigserial") == 0 ||
  				 strcmp(typname, "serial8") == 0)
  		{
  			is_serial = true;
  			column->typeName->names = NIL;
  			column->typeName->typeOid = INT8OID;
  		}
  
  		/*
  		 * We have to reject "serial[]" explicitly, because once we've set
  		 * typeid, LookupTypeName won't notice arrayBounds.  We don't need any
  		 * special coding for serial(typmod) though.
  		 */
  		if (is_serial && column->typeName->arrayBounds != NIL)
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("array of serial is not implemented"),
  					 parser_errposition(cxt->pstate,
  										column->typeName->location)));
  	}
  
  	/* Do necessary work on the column type declaration */
  	if (column->typeName)
  		transformColumnType(cxt, column);
  
  	/* Special actions for SERIAL pseudo-types */
  	if (is_serial)
  	{
  		char	   *snamespace;
  		char	   *sname;
  		char	   *qstring;
  		A_Const    *snamenode;
  		TypeCast   *castnode;
  		FuncCall   *funccallnode;
  		Constraint *constraint;
  
  		generateSerialExtraStmts(cxt, column,
  								 column->typeName->typeOid, NIL, false,
  								 &snamespace, &sname);
  
  		/*
  		 * Create appropriate constraints for SERIAL.  We do this in full,
  		 * rather than shortcutting, so that we will detect any conflicting
  		 * constraints the user wrote (like a different DEFAULT).
  		 *
  		 * Create an expression tree representing the function call
  		 * nextval('sequencename').  We cannot reduce the raw tree to cooked
  		 * form until after the sequence is created, but there's no need to do
  		 * so.
  		 */
  		qstring = quote_qualified_identifier(snamespace, sname);
  		snamenode = makeNode(A_Const);
  		snamenode->val.type = T_String;
  		snamenode->val.val.str = qstring;
  		snamenode->location = -1;
  		castnode = makeNode(TypeCast);
  		castnode->typeName = SystemTypeName("regclass");
  		castnode->arg = (Node *) snamenode;
  		castnode->location = -1;
  		funccallnode = makeFuncCall(SystemFuncName("nextval"),
  									list_make1(castnode),
  									-1);
  		constraint = makeNode(Constraint);
  		constraint->contype = CONSTR_DEFAULT;
  		constraint->location = -1;
  		constraint->raw_expr = (Node *) funccallnode;
  		constraint->cooked_expr = NULL;
  		column->constraints = lappend(column->constraints, constraint);
  
  		constraint = makeNode(Constraint);
  		constraint->contype = CONSTR_NOTNULL;
  		constraint->location = -1;
  		column->constraints = lappend(column->constraints, constraint);
  	}
  
  	/* Process column constraints, if any... */
  	transformConstraintAttrs(cxt, column->constraints);
  
  	saw_nullable = false;
  	saw_default = false;
  	saw_identity = false;
  	saw_generated = false;
  
  	foreach(clist, column->constraints)
  	{
  		Constraint *constraint = lfirst_node(Constraint, clist);
  
  		switch (constraint->contype)
  		{
  			case CONSTR_NULL:
  				if (saw_nullable && column->is_not_null)
  					ereport(ERROR,
  							(errcode(ERRCODE_SYNTAX_ERROR),
  							 errmsg("conflicting NULL/NOT NULL declarations for column \"%s\" of table \"%s\"",
  									column->colname, cxt->relation->relname),
  							 parser_errposition(cxt->pstate,
  												constraint->location)));
  				column->is_not_null = false;
  				saw_nullable = true;
  				break;
  
  			case CONSTR_NOTNULL:
  				if (saw_nullable && !column->is_not_null)
  					ereport(ERROR,
  							(errcode(ERRCODE_SYNTAX_ERROR),
  							 errmsg("conflicting NULL/NOT NULL declarations for column \"%s\" of table \"%s\"",
  									column->colname, cxt->relation->relname),
  							 parser_errposition(cxt->pstate,
  												constraint->location)));
  				column->is_not_null = true;
  				saw_nullable = true;
  				break;
  
  			case CONSTR_DEFAULT:
  				if (saw_default)
  					ereport(ERROR,
  							(errcode(ERRCODE_SYNTAX_ERROR),
  							 errmsg("multiple default values specified for column \"%s\" of table \"%s\"",
  									column->colname, cxt->relation->relname),
  							 parser_errposition(cxt->pstate,
  												constraint->location)));
  				column->raw_default = constraint->raw_expr;
  				Assert(constraint->cooked_expr == NULL);
  				saw_default = true;
  				break;
  
  			case CONSTR_IDENTITY:
  				{
  					Type		ctype;
  					Oid			typeOid;
  
  					if (cxt->ofType)
  						ereport(ERROR,
  								(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  								 errmsg("identity columns are not supported on typed tables")));
  					if (cxt->partbound)
  						ereport(ERROR,
  								(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  								 errmsg("identity columns are not supported on partitions")));
  
  					ctype = typenameType(cxt->pstate, column->typeName, NULL);
  					typeOid = ((Form_pg_type) GETSTRUCT(ctype))->oid;
  					ReleaseSysCache(ctype);
  
  					if (saw_identity)
  						ereport(ERROR,
  								(errcode(ERRCODE_SYNTAX_ERROR),
  								 errmsg("multiple identity specifications for column \"%s\" of table \"%s\"",
  										column->colname, cxt->relation->relname),
  								 parser_errposition(cxt->pstate,
  													constraint->location)));
  
  					generateSerialExtraStmts(cxt, column,
  											 typeOid, constraint->options, true,
  											 NULL, NULL);
  
  					column->identity = constraint->generated_when;
  					saw_identity = true;
  					column->is_not_null = true;
  					break;
  				}
  
  			case CONSTR_GENERATED:
  				if (cxt->ofType)
  					ereport(ERROR,
  							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  							 errmsg("generated columns are not supported on typed tables")));
  				if (cxt->partbound)
  					ereport(ERROR,
  							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  							 errmsg("generated columns are not supported on partitions")));
  
  				if (saw_generated)
  					ereport(ERROR,
  							(errcode(ERRCODE_SYNTAX_ERROR),
  							 errmsg("multiple generation clauses specified for column \"%s\" of table \"%s\"",
  									column->colname, cxt->relation->relname),
  							 parser_errposition(cxt->pstate,
  												constraint->location)));
  				column->generated = ATTRIBUTE_GENERATED_STORED;
  				column->raw_default = constraint->raw_expr;
  				Assert(constraint->cooked_expr == NULL);
  				saw_generated = true;
  				break;
  
  			case CONSTR_CHECK:
  				cxt->ckconstraints = lappend(cxt->ckconstraints, constraint);
  				break;
  
  			case CONSTR_PRIMARY:
  				if (cxt->isforeign)
  					ereport(ERROR,
  							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  							 errmsg("primary key constraints are not supported on foreign tables"),
  							 parser_errposition(cxt->pstate,
  												constraint->location)));
  				/* FALL THRU */
  
  			case CONSTR_UNIQUE:
  				if (cxt->isforeign)
  					ereport(ERROR,
  							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  							 errmsg("unique constraints are not supported on foreign tables"),
  							 parser_errposition(cxt->pstate,
  												constraint->location)));
  				if (constraint->keys == NIL)
  					constraint->keys = list_make1(makeString(column->colname));
  				cxt->ixconstraints = lappend(cxt->ixconstraints, constraint);
  				break;
  
  			case CONSTR_EXCLUSION:
  				/* grammar does not allow EXCLUDE as a column constraint */
  				elog(ERROR, "column exclusion constraints are not supported");
  				break;
  
  			case CONSTR_FOREIGN:
  				if (cxt->isforeign)
  					ereport(ERROR,
  							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  							 errmsg("foreign key constraints are not supported on foreign tables"),
  							 parser_errposition(cxt->pstate,
  												constraint->location)));
  
  				/*
  				 * Fill in the current attribute's name and throw it into the
  				 * list of FK constraints to be processed later.
  				 */
  				constraint->fk_attrs = list_make1(makeString(column->colname));
  				cxt->fkconstraints = lappend(cxt->fkconstraints, constraint);
  				break;
  
  			case CONSTR_ATTR_DEFERRABLE:
  			case CONSTR_ATTR_NOT_DEFERRABLE:
  			case CONSTR_ATTR_DEFERRED:
  			case CONSTR_ATTR_IMMEDIATE:
  				/* transformConstraintAttrs took care of these */
  				break;
  
  			default:
  				elog(ERROR, "unrecognized constraint type: %d",
  					 constraint->contype);
  				break;
  		}
  
  		if (saw_default && saw_identity)
  			ereport(ERROR,
  					(errcode(ERRCODE_SYNTAX_ERROR),
  					 errmsg("both default and identity specified for column \"%s\" of table \"%s\"",
  							column->colname, cxt->relation->relname),
  					 parser_errposition(cxt->pstate,
  										constraint->location)));
  
  		if (saw_default && saw_generated)
  			ereport(ERROR,
  					(errcode(ERRCODE_SYNTAX_ERROR),
  					 errmsg("both default and generation expression specified for column \"%s\" of table \"%s\"",
  							column->colname, cxt->relation->relname),
  					 parser_errposition(cxt->pstate,
  										constraint->location)));
  
  		if (saw_identity && saw_generated)
  			ereport(ERROR,
  					(errcode(ERRCODE_SYNTAX_ERROR),
  					 errmsg("both identity and generation expression specified for column \"%s\" of table \"%s\"",
  							column->colname, cxt->relation->relname),
  					 parser_errposition(cxt->pstate,
  										constraint->location)));
  	}
  
  	/*
  	 * If needed, generate ALTER FOREIGN TABLE ALTER COLUMN statement to add
  	 * per-column foreign data wrapper options to this column after creation.
  	 */
  	if (column->fdwoptions != NIL)
  	{
  		AlterTableStmt *stmt;
  		AlterTableCmd *cmd;
  
  		cmd = makeNode(AlterTableCmd);
  		cmd->subtype = AT_AlterColumnGenericOptions;
  		cmd->name = column->colname;
  		cmd->def = (Node *) column->fdwoptions;
  		cmd->behavior = DROP_RESTRICT;
  		cmd->missing_ok = false;
  
  		stmt = makeNode(AlterTableStmt);
  		stmt->relation = cxt->relation;
  		stmt->cmds = NIL;
  		stmt->relkind = OBJECT_FOREIGN_TABLE;
  		stmt->cmds = lappend(stmt->cmds, cmd);
  
  		cxt->alist = lappend(cxt->alist, stmt);
  	}
  }
  
  /*
   * transformTableConstraint
   *		transform a Constraint node within CREATE TABLE or ALTER TABLE
   */
  static void
  transformTableConstraint(CreateStmtContext *cxt, Constraint *constraint)
  {
  	switch (constraint->contype)
  	{
  		case CONSTR_PRIMARY:
  			if (cxt->isforeign)
  				ereport(ERROR,
  						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  						 errmsg("primary key constraints are not supported on foreign tables"),
  						 parser_errposition(cxt->pstate,
  											constraint->location)));
  			cxt->ixconstraints = lappend(cxt->ixconstraints, constraint);
  			break;
  
  		case CONSTR_UNIQUE:
  			if (cxt->isforeign)
  				ereport(ERROR,
  						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  						 errmsg("unique constraints are not supported on foreign tables"),
  						 parser_errposition(cxt->pstate,
  											constraint->location)));
  			cxt->ixconstraints = lappend(cxt->ixconstraints, constraint);
  			break;
  
  		case CONSTR_EXCLUSION:
  			if (cxt->isforeign)
  				ereport(ERROR,
  						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  						 errmsg("exclusion constraints are not supported on foreign tables"),
  						 parser_errposition(cxt->pstate,
  											constraint->location)));
  			if (cxt->ispartitioned)
  				ereport(ERROR,
  						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  						 errmsg("exclusion constraints are not supported on partitioned tables"),
  						 parser_errposition(cxt->pstate,
  											constraint->location)));
  			cxt->ixconstraints = lappend(cxt->ixconstraints, constraint);
  			break;
  
  		case CONSTR_CHECK:
  			cxt->ckconstraints = lappend(cxt->ckconstraints, constraint);
  			break;
  
  		case CONSTR_FOREIGN:
  			if (cxt->isforeign)
  				ereport(ERROR,
  						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  						 errmsg("foreign key constraints are not supported on foreign tables"),
  						 parser_errposition(cxt->pstate,
  											constraint->location)));
  			cxt->fkconstraints = lappend(cxt->fkconstraints, constraint);
  			break;
  
  		case CONSTR_NULL:
  		case CONSTR_NOTNULL:
  		case CONSTR_DEFAULT:
  		case CONSTR_ATTR_DEFERRABLE:
  		case CONSTR_ATTR_NOT_DEFERRABLE:
  		case CONSTR_ATTR_DEFERRED:
  		case CONSTR_ATTR_IMMEDIATE:
  			elog(ERROR, "invalid context for constraint type %d",
  				 constraint->contype);
  			break;
  
  		default:
  			elog(ERROR, "unrecognized constraint type: %d",
  				 constraint->contype);
  			break;
  	}
  }
  
  /*
   * transformTableLikeClause
   *
   * Change the LIKE <srctable> portion of a CREATE TABLE statement into
   * column definitions which recreate the user defined column portions of
   * <srctable>.
   */
  static void
  transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_clause)
  {
  	AttrNumber	parent_attno;
  	Relation	relation;
  	TupleDesc	tupleDesc;
  	TupleConstr *constr;
  	AttrNumber *attmap;
  	AclResult	aclresult;
  	char	   *comment;
  	ParseCallbackState pcbstate;
  
  	setup_parser_errposition_callback(&pcbstate, cxt->pstate,
  									  table_like_clause->relation->location);
  
  	/* we could support LIKE in many cases, but worry about it another day */
  	if (cxt->isforeign)
  		ereport(ERROR,
  				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  				 errmsg("LIKE is not supported for creating foreign tables")));
  
  	relation = relation_openrv(table_like_clause->relation, AccessShareLock);
  
  	if (relation->rd_rel->relkind != RELKIND_RELATION &&
  		relation->rd_rel->relkind != RELKIND_VIEW &&
  		relation->rd_rel->relkind != RELKIND_MATVIEW &&
  		relation->rd_rel->relkind != RELKIND_COMPOSITE_TYPE &&
  		relation->rd_rel->relkind != RELKIND_FOREIGN_TABLE &&
  		relation->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
  		ereport(ERROR,
  				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  				 errmsg("\"%s\" is not a table, view, materialized view, composite type, or foreign table",
  						RelationGetRelationName(relation))));
  
  	cancel_parser_errposition_callback(&pcbstate);
  
  	/*
  	 * Check for privileges
  	 */
  	if (relation->rd_rel->relkind == RELKIND_COMPOSITE_TYPE)
  	{
  		aclresult = pg_type_aclcheck(relation->rd_rel->reltype, GetUserId(),
  									 ACL_USAGE);
  		if (aclresult != ACLCHECK_OK)
  			aclcheck_error(aclresult, OBJECT_TYPE,
  						   RelationGetRelationName(relation));
  	}
  	else
  	{
  		aclresult = pg_class_aclcheck(RelationGetRelid(relation), GetUserId(),
  									  ACL_SELECT);
  		if (aclresult != ACLCHECK_OK)
  			aclcheck_error(aclresult, get_relkind_objtype(relation->rd_rel->relkind),
  						   RelationGetRelationName(relation));
  	}
  
  	tupleDesc = RelationGetDescr(relation);
  	constr = tupleDesc->constr;
  
  	/*
  	 * Initialize column number map for map_variable_attnos().  We need this
  	 * since dropped columns in the source table aren't copied, so the new
  	 * table can have different column numbers.
  	 */
  	attmap = (AttrNumber *) palloc0(sizeof(AttrNumber) * tupleDesc->natts);
  
  	/*
  	 * Insert the copied attributes into the cxt for the new table definition.
  	 */
  	for (parent_attno = 1; parent_attno <= tupleDesc->natts;
  		 parent_attno++)
  	{
  		Form_pg_attribute attribute = TupleDescAttr(tupleDesc,
  													parent_attno - 1);
  		char	   *attributeName = NameStr(attribute->attname);
  		ColumnDef  *def;
  
  		/*
  		 * Ignore dropped columns in the parent.  attmap entry is left zero.
  		 */
  		if (attribute->attisdropped)
  			continue;
  
  		/*
  		 * Create a new column, which is marked as NOT inherited.
  		 *
  		 * For constraints, ONLY the NOT NULL constraint is inherited by the
  		 * new column definition per SQL99.
  		 */
  		def = makeNode(ColumnDef);
  		def->colname = pstrdup(attributeName);
  		def->typeName = makeTypeNameFromOid(attribute->atttypid,
  											attribute->atttypmod);
  		def->inhcount = 0;
  		def->is_local = true;
  		def->is_not_null = attribute->attnotnull;
  		def->is_from_type = false;
  		def->storage = 0;
  		def->raw_default = NULL;
  		def->cooked_default = NULL;
  		def->collClause = NULL;
  		def->collOid = attribute->attcollation;
  		def->constraints = NIL;
  		def->location = -1;
  
  		/*
  		 * Add to column list
  		 */
  		cxt->columns = lappend(cxt->columns, def);
  
  		attmap[parent_attno - 1] = list_length(cxt->columns);
  
  		/*
  		 * Copy default, if present and it should be copied.  We have separate
  		 * options for plain default expressions and GENERATED defaults.
  		 */
  		if (attribute->atthasdef &&
  			(attribute->attgenerated ?
  			 (table_like_clause->options & CREATE_TABLE_LIKE_GENERATED) :
  			 (table_like_clause->options & CREATE_TABLE_LIKE_DEFAULTS)))
  		{
  			Node	   *this_default = NULL;
  			AttrDefault *attrdef;
  			int			i;
  			bool		found_whole_row;
  
  			/* Find default in constraint structure */
  			Assert(constr != NULL);
  			attrdef = constr->defval;
  			for (i = 0; i < constr->num_defval; i++)
  			{
  				if (attrdef[i].adnum == parent_attno)
  				{
  					this_default = stringToNode(attrdef[i].adbin);
  					break;
  				}
  			}
  			Assert(this_default != NULL);
  
  			def->cooked_default = map_variable_attnos(this_default,
  													  1, 0,
  													  attmap, tupleDesc->natts,
  													  InvalidOid, &found_whole_row);
  
  			/*
  			 * Prevent this for the same reason as for constraints below. Note
  			 * that defaults cannot contain any vars, so it's OK that the
  			 * error message refers to generated columns.
  			 */
  			if (found_whole_row)
  				ereport(ERROR,
  						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  						 errmsg("cannot convert whole-row table reference"),
  						 errdetail("Generation expression for column \"%s\" contains a whole-row reference to table \"%s\".",
  								   attributeName,
  								   RelationGetRelationName(relation))));
  
  			def->generated = attribute->attgenerated;
  		}
  
  		/*
  		 * Copy identity if requested
  		 */
  		if (attribute->attidentity &&
  			(table_like_clause->options & CREATE_TABLE_LIKE_IDENTITY))
  		{
  			Oid			seq_relid;
  			List	   *seq_options;
  
  			/*
  			 * find sequence owned by old column; extract sequence parameters;
  			 * build new create sequence command
  			 */
  			seq_relid = getIdentitySequence(RelationGetRelid(relation), attribute->attnum, false);
  			seq_options = sequence_options(seq_relid);
  			generateSerialExtraStmts(cxt, def,
  									 InvalidOid, seq_options, true,
  									 NULL, NULL);
  			def->identity = attribute->attidentity;
  		}
  
  		/* Likewise, copy storage if requested */
  		if (table_like_clause->options & CREATE_TABLE_LIKE_STORAGE)
  			def->storage = attribute->attstorage;
  		else
  			def->storage = 0;
  
  		/* Likewise, copy comment if requested */
  		if ((table_like_clause->options & CREATE_TABLE_LIKE_COMMENTS) &&
  			(comment = GetComment(attribute->attrelid,
  								  RelationRelationId,
  								  attribute->attnum)) != NULL)
  		{
  			CommentStmt *stmt = makeNode(CommentStmt);
  
  			stmt->objtype = OBJECT_COLUMN;
  			stmt->object = (Node *) list_make3(makeString(cxt->relation->schemaname),
  											   makeString(cxt->relation->relname),
  											   makeString(def->colname));
  			stmt->comment = comment;
  
  			cxt->alist = lappend(cxt->alist, stmt);
  		}
  	}
  
  	/*
  	 * Copy CHECK constraints if requested, being careful to adjust attribute
  	 * numbers so they match the child.
  	 */
  	if ((table_like_clause->options & CREATE_TABLE_LIKE_CONSTRAINTS) &&
  		tupleDesc->constr)
  	{
  		int			ccnum;
  
  		for (ccnum = 0; ccnum < tupleDesc->constr->num_check; ccnum++)
  		{
  			char	   *ccname = tupleDesc->constr->check[ccnum].ccname;
  			char	   *ccbin = tupleDesc->constr->check[ccnum].ccbin;
  			Constraint *n = makeNode(Constraint);
  			Node	   *ccbin_node;
  			bool		found_whole_row;
  
  			ccbin_node = map_variable_attnos(stringToNode(ccbin),
  											 1, 0,
  											 attmap, tupleDesc->natts,
  											 InvalidOid, &found_whole_row);
  
  			/*
  			 * We reject whole-row variables because the whole point of LIKE
  			 * is that the new table's rowtype might later diverge from the
  			 * parent's.  So, while translation might be possible right now,
  			 * it wouldn't be possible to guarantee it would work in future.
  			 */
  			if (found_whole_row)
  				ereport(ERROR,
  						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  						 errmsg("cannot convert whole-row table reference"),
  						 errdetail("Constraint \"%s\" contains a whole-row reference to table \"%s\".",
  								   ccname,
  								   RelationGetRelationName(relation))));
  
  			n->contype = CONSTR_CHECK;
  			n->location = -1;
  			n->conname = pstrdup(ccname);
  			n->raw_expr = NULL;
  			n->cooked_expr = nodeToString(ccbin_node);
  			cxt->ckconstraints = lappend(cxt->ckconstraints, n);
  
  			/* Copy comment on constraint */
  			if ((table_like_clause->options & CREATE_TABLE_LIKE_COMMENTS) &&
  				(comment = GetComment(get_relation_constraint_oid(RelationGetRelid(relation),
  																  n->conname, false),
  									  ConstraintRelationId,
  									  0)) != NULL)
  			{
  				CommentStmt *stmt = makeNode(CommentStmt);
  
  				stmt->objtype = OBJECT_TABCONSTRAINT;
  				stmt->object = (Node *) list_make3(makeString(cxt->relation->schemaname),
  												   makeString(cxt->relation->relname),
  												   makeString(n->conname));
  				stmt->comment = comment;
  
  				cxt->alist = lappend(cxt->alist, stmt);
  			}
  		}
  	}
  
  	/*
  	 * Likewise, copy indexes if requested
  	 */
  	if ((table_like_clause->options & CREATE_TABLE_LIKE_INDEXES) &&
  		relation->rd_rel->relhasindex)
  	{
  		List	   *parent_indexes;
  		ListCell   *l;
  
  		parent_indexes = RelationGetIndexList(relation);
  
  		foreach(l, parent_indexes)
  		{
  			Oid			parent_index_oid = lfirst_oid(l);
  			Relation	parent_index;
  			IndexStmt  *index_stmt;
  
  			parent_index = index_open(parent_index_oid, AccessShareLock);
  
  			/* Build CREATE INDEX statement to recreate the parent_index */
  			index_stmt = generateClonedIndexStmt(cxt->relation,
  												 parent_index,
  												 attmap, tupleDesc->natts,
  												 NULL);
  
  			/* Copy comment on index, if requested */
  			if (table_like_clause->options & CREATE_TABLE_LIKE_COMMENTS)
  			{
  				comment = GetComment(parent_index_oid, RelationRelationId, 0);
  
  				/*
  				 * We make use of IndexStmt's idxcomment option, so as not to
  				 * need to know now what name the index will have.
  				 */
  				index_stmt->idxcomment = comment;
  			}
  
  			/* Save it in the inh_indexes list for the time being */
  			cxt->inh_indexes = lappend(cxt->inh_indexes, index_stmt);
  
  			index_close(parent_index, AccessShareLock);
  		}
  	}
  
  	/*
  	 * Likewise, copy extended statistics if requested
  	 */
  	if (table_like_clause->options & CREATE_TABLE_LIKE_STATISTICS)
  	{
  		List	   *parent_extstats;
  		ListCell   *l;
  
  		parent_extstats = RelationGetStatExtList(relation);
  
  		foreach(l, parent_extstats)
  		{
  			Oid			parent_stat_oid = lfirst_oid(l);
  			CreateStatsStmt *stats_stmt;
  
  			stats_stmt = generateClonedExtStatsStmt(cxt->relation,
  													RelationGetRelid(relation),
  													parent_stat_oid);
  
  			/* Copy comment on statistics object, if requested */
  			if (table_like_clause->options & CREATE_TABLE_LIKE_COMMENTS)
  			{
  				comment = GetComment(parent_stat_oid, StatisticExtRelationId, 0);
  
  				/*
  				 * We make use of CreateStatsStmt's stxcomment option, so as
  				 * not to need to know now what name the statistics will have.
  				 */
  				stats_stmt->stxcomment = comment;
  			}
  
  			cxt->extstats = lappend(cxt->extstats, stats_stmt);
  		}
  
  		list_free(parent_extstats);
  	}
  
  	/*
  	 * Close the parent rel, but keep our AccessShareLock on it until xact
  	 * commit.  That will prevent someone else from deleting or ALTERing the
  	 * parent before the child is committed.
  	 */
  	table_close(relation, NoLock);
  }
  
  static void
  transformOfType(CreateStmtContext *cxt, TypeName *ofTypename)
  {
  	HeapTuple	tuple;
  	TupleDesc	tupdesc;
  	int			i;
  	Oid			ofTypeId;
  
  	AssertArg(ofTypename);
  
  	tuple = typenameType(NULL, ofTypename, NULL);
  	check_of_type(tuple);
  	ofTypeId = ((Form_pg_type) GETSTRUCT(tuple))->oid;
  	ofTypename->typeOid = ofTypeId; /* cached for later */
  
  	tupdesc = lookup_rowtype_tupdesc(ofTypeId, -1);
  	for (i = 0; i < tupdesc->natts; i++)
  	{
  		Form_pg_attribute attr = TupleDescAttr(tupdesc, i);
  		ColumnDef  *n;
  
  		if (attr->attisdropped)
  			continue;
  
  		n = makeNode(ColumnDef);
  		n->colname = pstrdup(NameStr(attr->attname));
  		n->typeName = makeTypeNameFromOid(attr->atttypid, attr->atttypmod);
  		n->inhcount = 0;
  		n->is_local = true;
  		n->is_not_null = false;
  		n->is_from_type = true;
  		n->storage = 0;
  		n->raw_default = NULL;
  		n->cooked_default = NULL;
  		n->collClause = NULL;
  		n->collOid = attr->attcollation;
  		n->constraints = NIL;
  		n->location = -1;
  		cxt->columns = lappend(cxt->columns, n);
  	}
  	DecrTupleDescRefCount(tupdesc);
  
  	ReleaseSysCache(tuple);
  }
  
  /*
   * Generate an IndexStmt node using information from an already existing index
   * "source_idx".
   *
   * heapRel is stored into the IndexStmt's relation field, but we don't use it
   * otherwise; some callers pass NULL, if they don't need it to be valid.
   * (The target relation might not exist yet, so we mustn't try to access it.)
   *
   * Attribute numbers in expression Vars are adjusted according to attmap.
   *
   * If constraintOid isn't NULL, we store the OID of any constraint associated
   * with the index there.
   *
   * Unlike transformIndexConstraint, we don't make any effort to force primary
   * key columns to be NOT NULL.  The larger cloning process this is part of
   * should have cloned their NOT NULL status separately (and DefineIndex will
   * complain if that fails to happen).
   */
  IndexStmt *
  generateClonedIndexStmt(RangeVar *heapRel, Relation source_idx,
  						const AttrNumber *attmap, int attmap_length,
  						Oid *constraintOid)
  {
  	Oid			source_relid = RelationGetRelid(source_idx);
  	HeapTuple	ht_idxrel;
  	HeapTuple	ht_idx;
  	HeapTuple	ht_am;
  	Form_pg_class idxrelrec;
  	Form_pg_index idxrec;
  	Form_pg_am	amrec;
  	oidvector  *indcollation;
  	oidvector  *indclass;
  	IndexStmt  *index;
  	List	   *indexprs;
  	ListCell   *indexpr_item;
  	Oid			indrelid;
  	int			keyno;
  	Oid			keycoltype;
  	Datum		datum;
  	bool		isnull;
  
  	if (constraintOid)
  		*constraintOid = InvalidOid;
  
  	/*
  	 * Fetch pg_class tuple of source index.  We can't use the copy in the
  	 * relcache entry because it doesn't include optional fields.
  	 */
  	ht_idxrel = SearchSysCache1(RELOID, ObjectIdGetDatum(source_relid));
  	if (!HeapTupleIsValid(ht_idxrel))
  		elog(ERROR, "cache lookup failed for relation %u", source_relid);
  	idxrelrec = (Form_pg_class) GETSTRUCT(ht_idxrel);
  
  	/* Fetch pg_index tuple for source index from relcache entry */
  	ht_idx = source_idx->rd_indextuple;
  	idxrec = (Form_pg_index) GETSTRUCT(ht_idx);
  	indrelid = idxrec->indrelid;
  
  	/* Fetch the pg_am tuple of the index' access method */
  	ht_am = SearchSysCache1(AMOID, ObjectIdGetDatum(idxrelrec->relam));
  	if (!HeapTupleIsValid(ht_am))
  		elog(ERROR, "cache lookup failed for access method %u",
  			 idxrelrec->relam);
  	amrec = (Form_pg_am) GETSTRUCT(ht_am);
  
  	/* Extract indcollation from the pg_index tuple */
  	datum = SysCacheGetAttr(INDEXRELID, ht_idx,
  							Anum_pg_index_indcollation, &isnull);
  	Assert(!isnull);
  	indcollation = (oidvector *) DatumGetPointer(datum);
  
  	/* Extract indclass from the pg_index tuple */
  	datum = SysCacheGetAttr(INDEXRELID, ht_idx,
  							Anum_pg_index_indclass, &isnull);
  	Assert(!isnull);
  	indclass = (oidvector *) DatumGetPointer(datum);
  
  	/* Begin building the IndexStmt */
  	index = makeNode(IndexStmt);
  	index->relation = heapRel;
  	index->accessMethod = pstrdup(NameStr(amrec->amname));
  	if (OidIsValid(idxrelrec->reltablespace))
  		index->tableSpace = get_tablespace_name(idxrelrec->reltablespace);
  	else
  		index->tableSpace = NULL;
  	index->excludeOpNames = NIL;
  	index->idxcomment = NULL;
  	index->indexOid = InvalidOid;
  	index->oldNode = InvalidOid;
  	index->unique = idxrec->indisunique;
  	index->primary = idxrec->indisprimary;
  	index->transformed = true;	/* don't need transformIndexStmt */
  	index->concurrent = false;
  	index->if_not_exists = false;
  	index->reset_default_tblspc = false;
  
  	/*
  	 * We don't try to preserve the name of the source index; instead, just
  	 * let DefineIndex() choose a reasonable name.  (If we tried to preserve
  	 * the name, we'd get duplicate-relation-name failures unless the source
  	 * table was in a different schema.)
  	 */
  	index->idxname = NULL;
  
  	/*
  	 * If the index is marked PRIMARY or has an exclusion condition, it's
  	 * certainly from a constraint; else, if it's not marked UNIQUE, it
  	 * certainly isn't.  If it is or might be from a constraint, we have to
  	 * fetch the pg_constraint record.
  	 */
  	if (index->primary || index->unique || idxrec->indisexclusion)
  	{
  		Oid			constraintId = get_index_constraint(source_relid);
  
  		if (OidIsValid(constraintId))
  		{
  			HeapTuple	ht_constr;
  			Form_pg_constraint conrec;
  
  			if (constraintOid)
  				*constraintOid = constraintId;
  
  			ht_constr = SearchSysCache1(CONSTROID,
  										ObjectIdGetDatum(constraintId));
  			if (!HeapTupleIsValid(ht_constr))
  				elog(ERROR, "cache lookup failed for constraint %u",
  					 constraintId);
  			conrec = (Form_pg_constraint) GETSTRUCT(ht_constr);
  
  			index->isconstraint = true;
  			index->deferrable = conrec->condeferrable;
  			index->initdeferred = conrec->condeferred;
  
  			/* If it's an exclusion constraint, we need the operator names */
  			if (idxrec->indisexclusion)
  			{
  				Datum	   *elems;
  				int			nElems;
  				int			i;
  
  				Assert(conrec->contype == CONSTRAINT_EXCLUSION);
  				/* Extract operator OIDs from the pg_constraint tuple */
  				datum = SysCacheGetAttr(CONSTROID, ht_constr,
  										Anum_pg_constraint_conexclop,
  										&isnull);
  				if (isnull)
  					elog(ERROR, "null conexclop for constraint %u",
  						 constraintId);
  
  				deconstruct_array(DatumGetArrayTypeP(datum),
  								  OIDOID, sizeof(Oid), true, 'i',
  								  &elems, NULL, &nElems);
  
  				for (i = 0; i < nElems; i++)
  				{
  					Oid			operid = DatumGetObjectId(elems[i]);
  					HeapTuple	opertup;
  					Form_pg_operator operform;
  					char	   *oprname;
  					char	   *nspname;
  					List	   *namelist;
  
  					opertup = SearchSysCache1(OPEROID,
  											  ObjectIdGetDatum(operid));
  					if (!HeapTupleIsValid(opertup))
  						elog(ERROR, "cache lookup failed for operator %u",
  							 operid);
  					operform = (Form_pg_operator) GETSTRUCT(opertup);
  					oprname = pstrdup(NameStr(operform->oprname));
  					/* For simplicity we always schema-qualify the op name */
  					nspname = get_namespace_name(operform->oprnamespace);
  					namelist = list_make2(makeString(nspname),
  										  makeString(oprname));
  					index->excludeOpNames = lappend(index->excludeOpNames,
  													namelist);
  					ReleaseSysCache(opertup);
  				}
  			}
  
  			ReleaseSysCache(ht_constr);
  		}
  		else
  			index->isconstraint = false;
  	}
  	else
  		index->isconstraint = false;
  
  	/* Get the index expressions, if any */
  	datum = SysCacheGetAttr(INDEXRELID, ht_idx,
  							Anum_pg_index_indexprs, &isnull);
  	if (!isnull)
  	{
  		char	   *exprsString;
  
  		exprsString = TextDatumGetCString(datum);
  		indexprs = (List *) stringToNode(exprsString);
  	}
  	else
  		indexprs = NIL;
  
  	/* Build the list of IndexElem */
  	index->indexParams = NIL;
  	index->indexIncludingParams = NIL;
  
  	indexpr_item = list_head(indexprs);
  	for (keyno = 0; keyno < idxrec->indnkeyatts; keyno++)
  	{
  		IndexElem  *iparam;
  		AttrNumber	attnum = idxrec->indkey.values[keyno];
  		Form_pg_attribute attr = TupleDescAttr(RelationGetDescr(source_idx),
  											   keyno);
  		int16		opt = source_idx->rd_indoption[keyno];
  
  		iparam = makeNode(IndexElem);
  
  		if (AttributeNumberIsValid(attnum))
  		{
  			/* Simple index column */
  			char	   *attname;
  
  			attname = get_attname(indrelid, attnum, false);
  			keycoltype = get_atttype(indrelid, attnum);
  
  			iparam->name = attname;
  			iparam->expr = NULL;
  		}
  		else
  		{
  			/* Expressional index */
  			Node	   *indexkey;
  			bool		found_whole_row;
  
  			if (indexpr_item == NULL)
  				elog(ERROR, "too few entries in indexprs list");
  			indexkey = (Node *) lfirst(indexpr_item);
  			indexpr_item = lnext(indexprs, indexpr_item);
  
  			/* Adjust Vars to match new table's column numbering */
  			indexkey = map_variable_attnos(indexkey,
  										   1, 0,
  										   attmap, attmap_length,
  										   InvalidOid, &found_whole_row);
  
  			/* As in transformTableLikeClause, reject whole-row variables */
  			if (found_whole_row)
  				ereport(ERROR,
  						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  						 errmsg("cannot convert whole-row table reference"),
  						 errdetail("Index \"%s\" contains a whole-row table reference.",
  								   RelationGetRelationName(source_idx))));
  
  			iparam->name = NULL;
  			iparam->expr = indexkey;
  
  			keycoltype = exprType(indexkey);
  		}
  
  		/* Copy the original index column name */
  		iparam->indexcolname = pstrdup(NameStr(attr->attname));
  
  		/* Add the collation name, if non-default */
  		iparam->collation = get_collation(indcollation->values[keyno], keycoltype);
  
  		/* Add the operator class name, if non-default */
  		iparam->opclass = get_opclass(indclass->values[keyno], keycoltype);
  
  		iparam->ordering = SORTBY_DEFAULT;
  		iparam->nulls_ordering = SORTBY_NULLS_DEFAULT;
  
  		/* Adjust options if necessary */
  		if (source_idx->rd_indam->amcanorder)
  		{
  			/*
  			 * If it supports sort ordering, copy DESC and NULLS opts. Don't
  			 * set non-default settings unnecessarily, though, so as to
  			 * improve the chance of recognizing equivalence to constraint
  			 * indexes.
  			 */
  			if (opt & INDOPTION_DESC)
  			{
  				iparam->ordering = SORTBY_DESC;
  				if ((opt & INDOPTION_NULLS_FIRST) == 0)
  					iparam->nulls_ordering = SORTBY_NULLS_LAST;
  			}
  			else
  			{
  				if (opt & INDOPTION_NULLS_FIRST)
  					iparam->nulls_ordering = SORTBY_NULLS_FIRST;
  			}
  		}
  
  		index->indexParams = lappend(index->indexParams, iparam);
  	}
  
  	/* Handle included columns separately */
  	for (keyno = idxrec->indnkeyatts; keyno < idxrec->indnatts; keyno++)
  	{
  		IndexElem  *iparam;
  		AttrNumber	attnum = idxrec->indkey.values[keyno];
  		Form_pg_attribute attr = TupleDescAttr(RelationGetDescr(source_idx),
  											   keyno);
  
  		iparam = makeNode(IndexElem);
  
  		if (AttributeNumberIsValid(attnum))
  		{
  			/* Simple index column */
  			char	   *attname;
  
  			attname = get_attname(indrelid, attnum, false);
  			keycoltype = get_atttype(indrelid, attnum);
  
  			iparam->name = attname;
  			iparam->expr = NULL;
  		}
  		else
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("expressions are not supported in included columns")));
  
  		/* Copy the original index column name */
  		iparam->indexcolname = pstrdup(NameStr(attr->attname));
  
  		index->indexIncludingParams = lappend(index->indexIncludingParams, iparam);
  	}
  	/* Copy reloptions if any */
  	datum = SysCacheGetAttr(RELOID, ht_idxrel,
  							Anum_pg_class_reloptions, &isnull);
  	if (!isnull)
  		index->options = untransformRelOptions(datum);
  
  	/* If it's a partial index, decompile and append the predicate */
  	datum = SysCacheGetAttr(INDEXRELID, ht_idx,
  							Anum_pg_index_indpred, &isnull);
  	if (!isnull)
  	{
  		char	   *pred_str;
  		Node	   *pred_tree;
  		bool		found_whole_row;
  
  		/* Convert text string to node tree */
  		pred_str = TextDatumGetCString(datum);
  		pred_tree = (Node *) stringToNode(pred_str);
  
  		/* Adjust Vars to match new table's column numbering */
  		pred_tree = map_variable_attnos(pred_tree,
  										1, 0,
  										attmap, attmap_length,
  										InvalidOid, &found_whole_row);
  
  		/* As in transformTableLikeClause, reject whole-row variables */
  		if (found_whole_row)
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("cannot convert whole-row table reference"),
  					 errdetail("Index \"%s\" contains a whole-row table reference.",
  							   RelationGetRelationName(source_idx))));
  
  		index->whereClause = pred_tree;
  	}
  
  	/* Clean up */
  	ReleaseSysCache(ht_idxrel);
  	ReleaseSysCache(ht_am);
  
  	return index;
  }
  
  /*
   * Generate a CreateStatsStmt node using information from an already existing
   * extended statistic "source_statsid", for the rel identified by heapRel and
   * heapRelid.
   */
  static CreateStatsStmt *
  generateClonedExtStatsStmt(RangeVar *heapRel, Oid heapRelid,
  						   Oid source_statsid)
  {
  	HeapTuple	ht_stats;
  	Form_pg_statistic_ext statsrec;
  	CreateStatsStmt *stats;
  	List	   *stat_types = NIL;
  	List	   *def_names = NIL;
  	bool		isnull;
  	Datum		datum;
  	ArrayType  *arr;
  	char	   *enabled;
  	int			i;
  
  	Assert(OidIsValid(heapRelid));
  	Assert(heapRel != NULL);
  
  	/*
  	 * Fetch pg_statistic_ext tuple of source statistics object.
  	 */
  	ht_stats = SearchSysCache1(STATEXTOID, ObjectIdGetDatum(source_statsid));
  	if (!HeapTupleIsValid(ht_stats))
  		elog(ERROR, "cache lookup failed for statistics object %u", source_statsid);
  	statsrec = (Form_pg_statistic_ext) GETSTRUCT(ht_stats);
  
  	/* Determine which statistics types exist */
  	datum = SysCacheGetAttr(STATEXTOID, ht_stats,
  							Anum_pg_statistic_ext_stxkind, &isnull);
  	Assert(!isnull);
  	arr = DatumGetArrayTypeP(datum);
  	if (ARR_NDIM(arr) != 1 ||
  		ARR_HASNULL(arr) ||
  		ARR_ELEMTYPE(arr) != CHAROID)
  		elog(ERROR, "stxkind is not a 1-D char array");
  	enabled = (char *) ARR_DATA_PTR(arr);
  	for (i = 0; i < ARR_DIMS(arr)[0]; i++)
  	{
  		if (enabled[i] == STATS_EXT_NDISTINCT)
  			stat_types = lappend(stat_types, makeString("ndistinct"));
  		else if (enabled[i] == STATS_EXT_DEPENDENCIES)
  			stat_types = lappend(stat_types, makeString("dependencies"));
  		else if (enabled[i] == STATS_EXT_MCV)
  			stat_types = lappend(stat_types, makeString("mcv"));
  		else
  			elog(ERROR, "unrecognized statistics kind %c", enabled[i]);
  	}
  
  	/* Determine which columns the statistics are on */
  	for (i = 0; i < statsrec->stxkeys.dim1; i++)
  	{
  		ColumnRef  *cref = makeNode(ColumnRef);
  		AttrNumber	attnum = statsrec->stxkeys.values[i];
  
  		cref->fields = list_make1(makeString(get_attname(heapRelid,
  														 attnum, false)));
  		cref->location = -1;
  
  		def_names = lappend(def_names, cref);
  	}
  
  	/* finally, build the output node */
  	stats = makeNode(CreateStatsStmt);
  	stats->defnames = NULL;
  	stats->stat_types = stat_types;
  	stats->exprs = def_names;
  	stats->relations = list_make1(heapRel);
  	stats->stxcomment = NULL;
  	stats->if_not_exists = false;
  
  	/* Clean up */
  	ReleaseSysCache(ht_stats);
  
  	return stats;
  }
  
  /*
   * get_collation		- fetch qualified name of a collation
   *
   * If collation is InvalidOid or is the default for the given actual_datatype,
   * then the return value is NIL.
   */
  static List *
  get_collation(Oid collation, Oid actual_datatype)
  {
  	List	   *result;
  	HeapTuple	ht_coll;
  	Form_pg_collation coll_rec;
  	char	   *nsp_name;
  	char	   *coll_name;
  
  	if (!OidIsValid(collation))
  		return NIL;				/* easy case */
  	if (collation == get_typcollation(actual_datatype))
  		return NIL;				/* just let it default */
  
  	ht_coll = SearchSysCache1(COLLOID, ObjectIdGetDatum(collation));
  	if (!HeapTupleIsValid(ht_coll))
  		elog(ERROR, "cache lookup failed for collation %u", collation);
  	coll_rec = (Form_pg_collation) GETSTRUCT(ht_coll);
  
  	/* For simplicity, we always schema-qualify the name */
  	nsp_name = get_namespace_name(coll_rec->collnamespace);
  	coll_name = pstrdup(NameStr(coll_rec->collname));
  	result = list_make2(makeString(nsp_name), makeString(coll_name));
  
  	ReleaseSysCache(ht_coll);
  	return result;
  }
  
  /*
   * get_opclass			- fetch qualified name of an index operator class
   *
   * If the opclass is the default for the given actual_datatype, then
   * the return value is NIL.
   */
  static List *
  get_opclass(Oid opclass, Oid actual_datatype)
  {
  	List	   *result = NIL;
  	HeapTuple	ht_opc;
  	Form_pg_opclass opc_rec;
  
  	ht_opc = SearchSysCache1(CLAOID, ObjectIdGetDatum(opclass));
  	if (!HeapTupleIsValid(ht_opc))
  		elog(ERROR, "cache lookup failed for opclass %u", opclass);
  	opc_rec = (Form_pg_opclass) GETSTRUCT(ht_opc);
  
  	if (GetDefaultOpClass(actual_datatype, opc_rec->opcmethod) != opclass)
  	{
  		/* For simplicity, we always schema-qualify the name */
  		char	   *nsp_name = get_namespace_name(opc_rec->opcnamespace);
  		char	   *opc_name = pstrdup(NameStr(opc_rec->opcname));
  
  		result = list_make2(makeString(nsp_name), makeString(opc_name));
  	}
  
  	ReleaseSysCache(ht_opc);
  	return result;
  }
  
  
  /*
   * transformIndexConstraints
   *		Handle UNIQUE, PRIMARY KEY, EXCLUDE constraints, which create indexes.
   *		We also merge in any index definitions arising from
   *		LIKE ... INCLUDING INDEXES.
   */
  static void
  transformIndexConstraints(CreateStmtContext *cxt)
  {
  	IndexStmt  *index;
  	List	   *indexlist = NIL;
  	List	   *finalindexlist = NIL;
  	ListCell   *lc;
  
  	/*
  	 * Run through the constraints that need to generate an index. For PRIMARY
  	 * KEY, mark each column as NOT NULL and create an index. For UNIQUE or
  	 * EXCLUDE, create an index as for PRIMARY KEY, but do not insist on NOT
  	 * NULL.
  	 */
  	foreach(lc, cxt->ixconstraints)
  	{
  		Constraint *constraint = lfirst_node(Constraint, lc);
  
  		Assert(constraint->contype == CONSTR_PRIMARY ||
  			   constraint->contype == CONSTR_UNIQUE ||
  			   constraint->contype == CONSTR_EXCLUSION);
  
  		index = transformIndexConstraint(constraint, cxt);
  
  		indexlist = lappend(indexlist, index);
  	}
  
  	/* Add in any indexes defined by LIKE ... INCLUDING INDEXES */
  	foreach(lc, cxt->inh_indexes)
  	{
  		index = (IndexStmt *) lfirst(lc);
  
  		if (index->primary)
  		{
  			if (cxt->pkey != NULL)
  				ereport(ERROR,
  						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
  						 errmsg("multiple primary keys for table \"%s\" are not allowed",
  								cxt->relation->relname)));
  			cxt->pkey = index;
  		}
  
  		indexlist = lappend(indexlist, index);
  	}
  
  	/*
  	 * Scan the index list and remove any redundant index specifications. This
  	 * can happen if, for instance, the user writes UNIQUE PRIMARY KEY. A
  	 * strict reading of SQL would suggest raising an error instead, but that
  	 * strikes me as too anal-retentive. - tgl 2001-02-14
  	 *
  	 * XXX in ALTER TABLE case, it'd be nice to look for duplicate
  	 * pre-existing indexes, too.
  	 */
  	if (cxt->pkey != NULL)
  	{
  		/* Make sure we keep the PKEY index in preference to others... */
  		finalindexlist = list_make1(cxt->pkey);
  	}
  
  	foreach(lc, indexlist)
  	{
  		bool		keep = true;
  		ListCell   *k;
  
  		index = lfirst(lc);
  
  		/* if it's pkey, it's already in finalindexlist */
  		if (index == cxt->pkey)
  			continue;
  
  		foreach(k, finalindexlist)
  		{
  			IndexStmt  *priorindex = lfirst(k);
  
  			if (equal(index->indexParams, priorindex->indexParams) &&
  				equal(index->indexIncludingParams, priorindex->indexIncludingParams) &&
  				equal(index->whereClause, priorindex->whereClause) &&
  				equal(index->excludeOpNames, priorindex->excludeOpNames) &&
  				strcmp(index->accessMethod, priorindex->accessMethod) == 0 &&
  				index->deferrable == priorindex->deferrable &&
  				index->initdeferred == priorindex->initdeferred)
  			{
  				priorindex->unique |= index->unique;
  
  				/*
  				 * If the prior index is as yet unnamed, and this one is
  				 * named, then transfer the name to the prior index. This
  				 * ensures that if we have named and unnamed constraints,
  				 * we'll use (at least one of) the names for the index.
  				 */
  				if (priorindex->idxname == NULL)
  					priorindex->idxname = index->idxname;
  				keep = false;
  				break;
  			}
  		}
  
  		if (keep)
  			finalindexlist = lappend(finalindexlist, index);
  	}
  
  	/*
  	 * Now append all the IndexStmts to cxt->alist.  If we generated an ALTER
  	 * TABLE SET NOT NULL statement to support a primary key, it's already in
  	 * cxt->alist.
  	 */
  	cxt->alist = list_concat(cxt->alist, finalindexlist);
  }
  
  /*
   * transformIndexConstraint
   *		Transform one UNIQUE, PRIMARY KEY, or EXCLUDE constraint for
   *		transformIndexConstraints.
   *
   * We return an IndexStmt.  For a PRIMARY KEY constraint, we additionally
   * produce NOT NULL constraints, either by marking ColumnDefs in cxt->columns
   * as is_not_null or by adding an ALTER TABLE SET NOT NULL command to
   * cxt->alist.
   */
  static IndexStmt *
  transformIndexConstraint(Constraint *constraint, CreateStmtContext *cxt)
  {
  	IndexStmt  *index;
  	List	   *notnullcmds = NIL;
  	ListCell   *lc;
  
  	index = makeNode(IndexStmt);
  
  	index->unique = (constraint->contype != CONSTR_EXCLUSION);
  	index->primary = (constraint->contype == CONSTR_PRIMARY);
  	if (index->primary)
  	{
  		if (cxt->pkey != NULL)
  			ereport(ERROR,
  					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
  					 errmsg("multiple primary keys for table \"%s\" are not allowed",
  							cxt->relation->relname),
  					 parser_errposition(cxt->pstate, constraint->location)));
  		cxt->pkey = index;
  
  		/*
  		 * In ALTER TABLE case, a primary index might already exist, but
  		 * DefineIndex will check for it.
  		 */
  	}
  	index->isconstraint = true;
  	index->deferrable = constraint->deferrable;
  	index->initdeferred = constraint->initdeferred;
  
  	if (constraint->conname != NULL)
  		index->idxname = pstrdup(constraint->conname);
  	else
  		index->idxname = NULL;	/* DefineIndex will choose name */
  
  	index->relation = cxt->relation;
  	index->accessMethod = constraint->access_method ? constraint->access_method : DEFAULT_INDEX_TYPE;
  	index->options = constraint->options;
  	index->tableSpace = constraint->indexspace;
  	index->whereClause = constraint->where_clause;
  	index->indexParams = NIL;
  	index->indexIncludingParams = NIL;
  	index->excludeOpNames = NIL;
  	index->idxcomment = NULL;
  	index->indexOid = InvalidOid;
  	index->oldNode = InvalidOid;
  	index->transformed = false;
  	index->concurrent = false;
  	index->if_not_exists = false;
  	index->reset_default_tblspc = constraint->reset_default_tblspc;
  
  	/*
  	 * If it's ALTER TABLE ADD CONSTRAINT USING INDEX, look up the index and
  	 * verify it's usable, then extract the implied column name list.  (We
  	 * will not actually need the column name list at runtime, but we need it
  	 * now to check for duplicate column entries below.)
  	 */
  	if (constraint->indexname != NULL)
  	{
  		char	   *index_name = constraint->indexname;
  		Relation	heap_rel = cxt->rel;
  		Oid			index_oid;
  		Relation	index_rel;
  		Form_pg_index index_form;
  		oidvector  *indclass;
  		Datum		indclassDatum;
  		bool		isnull;
  		int			i;
  
  		/* Grammar should not allow this with explicit column list */
  		Assert(constraint->keys == NIL);
  
  		/* Grammar should only allow PRIMARY and UNIQUE constraints */
  		Assert(constraint->contype == CONSTR_PRIMARY ||
  			   constraint->contype == CONSTR_UNIQUE);
  
  		/* Must be ALTER, not CREATE, but grammar doesn't enforce that */
  		if (!cxt->isalter)
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("cannot use an existing index in CREATE TABLE"),
  					 parser_errposition(cxt->pstate, constraint->location)));
  
  		/* Look for the index in the same schema as the table */
  		index_oid = get_relname_relid(index_name, RelationGetNamespace(heap_rel));
  
  		if (!OidIsValid(index_oid))
  			ereport(ERROR,
  					(errcode(ERRCODE_UNDEFINED_OBJECT),
  					 errmsg("index \"%s\" does not exist", index_name),
  					 parser_errposition(cxt->pstate, constraint->location)));
  
  		/* Open the index (this will throw an error if it is not an index) */
  		index_rel = index_open(index_oid, AccessShareLock);
  		index_form = index_rel->rd_index;
  
  		/* Check that it does not have an associated constraint already */
  		if (OidIsValid(get_index_constraint(index_oid)))
  			ereport(ERROR,
  					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
  					 errmsg("index \"%s\" is already associated with a constraint",
  							index_name),
  					 parser_errposition(cxt->pstate, constraint->location)));
  
  		/* Perform validity checks on the index */
  		if (index_form->indrelid != RelationGetRelid(heap_rel))
  			ereport(ERROR,
  					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
  					 errmsg("index \"%s\" does not belong to table \"%s\"",
  							index_name, RelationGetRelationName(heap_rel)),
  					 parser_errposition(cxt->pstate, constraint->location)));
  
  		if (!index_form->indisvalid)
  			ereport(ERROR,
  					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
  					 errmsg("index \"%s\" is not valid", index_name),
  					 parser_errposition(cxt->pstate, constraint->location)));
  
  		if (!index_form->indisunique)
  			ereport(ERROR,
  					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  					 errmsg("\"%s\" is not a unique index", index_name),
  					 errdetail("Cannot create a primary key or unique constraint using such an index."),
  					 parser_errposition(cxt->pstate, constraint->location)));
  
  		if (RelationGetIndexExpressions(index_rel) != NIL)
  			ereport(ERROR,
  					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  					 errmsg("index \"%s\" contains expressions", index_name),
  					 errdetail("Cannot create a primary key or unique constraint using such an index."),
  					 parser_errposition(cxt->pstate, constraint->location)));
  
  		if (RelationGetIndexPredicate(index_rel) != NIL)
  			ereport(ERROR,
  					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  					 errmsg("\"%s\" is a partial index", index_name),
  					 errdetail("Cannot create a primary key or unique constraint using such an index."),
  					 parser_errposition(cxt->pstate, constraint->location)));
  
  		/*
  		 * It's probably unsafe to change a deferred index to non-deferred. (A
  		 * non-constraint index couldn't be deferred anyway, so this case
  		 * should never occur; no need to sweat, but let's check it.)
  		 */
  		if (!index_form->indimmediate && !constraint->deferrable)
  			ereport(ERROR,
  					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  					 errmsg("\"%s\" is a deferrable index", index_name),
  					 errdetail("Cannot create a non-deferrable constraint using a deferrable index."),
  					 parser_errposition(cxt->pstate, constraint->location)));
  
  		/*
  		 * Insist on it being a btree.  That's the only kind that supports
  		 * uniqueness at the moment anyway; but we must have an index that
  		 * exactly matches what you'd get from plain ADD CONSTRAINT syntax,
  		 * else dump and reload will produce a different index (breaking
  		 * pg_upgrade in particular).
  		 */
  		if (index_rel->rd_rel->relam != get_index_am_oid(DEFAULT_INDEX_TYPE, false))
  			ereport(ERROR,
  					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  					 errmsg("index \"%s\" is not a btree", index_name),
  					 parser_errposition(cxt->pstate, constraint->location)));
  
  		/* Must get indclass the hard way */
  		indclassDatum = SysCacheGetAttr(INDEXRELID, index_rel->rd_indextuple,
  										Anum_pg_index_indclass, &isnull);
  		Assert(!isnull);
  		indclass = (oidvector *) DatumGetPointer(indclassDatum);
  
  		for (i = 0; i < index_form->indnatts; i++)
  		{
  			int16		attnum = index_form->indkey.values[i];
  			const FormData_pg_attribute *attform;
  			char	   *attname;
  			Oid			defopclass;
  
  			/*
  			 * We shouldn't see attnum == 0 here, since we already rejected
  			 * expression indexes.  If we do, SystemAttributeDefinition will
  			 * throw an error.
  			 */
  			if (attnum > 0)
  			{
  				Assert(attnum <= heap_rel->rd_att->natts);
  				attform = TupleDescAttr(heap_rel->rd_att, attnum - 1);
  			}
  			else
  				attform = SystemAttributeDefinition(attnum);
  			attname = pstrdup(NameStr(attform->attname));
  
  			if (i < index_form->indnkeyatts)
  			{
  				/*
  				 * Insist on default opclass, collation, and sort options.
  				 * While the index would still work as a constraint with
  				 * non-default settings, it might not provide exactly the same
  				 * uniqueness semantics as you'd get from a normally-created
  				 * constraint; and there's also the dump/reload problem
  				 * mentioned above.
  				 */
  				defopclass = GetDefaultOpClass(attform->atttypid,
  											   index_rel->rd_rel->relam);
  				if (indclass->values[i] != defopclass ||
  					attform->attcollation != index_rel->rd_indcollation[i] ||
  					index_rel->rd_indoption[i] != 0)
  					ereport(ERROR,
  							(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  							 errmsg("index \"%s\" column number %d does not have default sorting behavior", index_name, i + 1),
  							 errdetail("Cannot create a primary key or unique constraint using such an index."),
  							 parser_errposition(cxt->pstate, constraint->location)));
  
  				constraint->keys = lappend(constraint->keys, makeString(attname));
  			}
  			else
  				constraint->including = lappend(constraint->including, makeString(attname));
  		}
  
  		/* Close the index relation but keep the lock */
  		relation_close(index_rel, NoLock);
  
  		index->indexOid = index_oid;
  	}
  
  	/*
  	 * If it's an EXCLUDE constraint, the grammar returns a list of pairs of
  	 * IndexElems and operator names.  We have to break that apart into
  	 * separate lists.
  	 */
  	if (constraint->contype == CONSTR_EXCLUSION)
  	{
  		foreach(lc, constraint->exclusions)
  		{
  			List	   *pair = (List *) lfirst(lc);
  			IndexElem  *elem;
  			List	   *opname;
  
  			Assert(list_length(pair) == 2);
  			elem = linitial_node(IndexElem, pair);
  			opname = lsecond_node(List, pair);
  
  			index->indexParams = lappend(index->indexParams, elem);
  			index->excludeOpNames = lappend(index->excludeOpNames, opname);
  		}
  	}
  
  	/*
  	 * For UNIQUE and PRIMARY KEY, we just have a list of column names.
  	 *
  	 * Make sure referenced keys exist.  If we are making a PRIMARY KEY index,
  	 * also make sure they are NOT NULL.
  	 */
  	else
  	{
  		foreach(lc, constraint->keys)
  		{
  			char	   *key = strVal(lfirst(lc));
  			bool		found = false;
  			bool		forced_not_null = false;
  			ColumnDef  *column = NULL;
  			ListCell   *columns;
  			IndexElem  *iparam;
  
  			/* Make sure referenced column exists. */
  			foreach(columns, cxt->columns)
  			{
  				column = castNode(ColumnDef, lfirst(columns));
  				if (strcmp(column->colname, key) == 0)
  				{
  					found = true;
  					break;
  				}
  			}
  			if (found)
  			{
  				/*
  				 * column is defined in the new table.  For PRIMARY KEY, we
  				 * can apply the NOT NULL constraint cheaply here ... unless
  				 * the column is marked is_from_type, in which case marking it
  				 * here would be ineffective (see MergeAttributes).
  				 */
  				if (constraint->contype == CONSTR_PRIMARY &&
  					!column->is_from_type)
  				{
  					column->is_not_null = true;
  					forced_not_null = true;
  				}
  			}
  			else if (SystemAttributeByName(key) != NULL)
  			{
  				/*
  				 * column will be a system column in the new table, so accept
  				 * it. System columns can't ever be null, so no need to worry
  				 * about PRIMARY/NOT NULL constraint.
  				 */
  				found = true;
  			}
  			else if (cxt->inhRelations)
  			{
  				/* try inherited tables */
  				ListCell   *inher;
  
  				foreach(inher, cxt->inhRelations)
  				{
  					RangeVar   *inh = castNode(RangeVar, lfirst(inher));
  					Relation	rel;
  					int			count;
  
  					rel = table_openrv(inh, AccessShareLock);
  					/* check user requested inheritance from valid relkind */
  					if (rel->rd_rel->relkind != RELKIND_RELATION &&
  						rel->rd_rel->relkind != RELKIND_FOREIGN_TABLE &&
  						rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
  						ereport(ERROR,
  								(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  								 errmsg("inherited relation \"%s\" is not a table or foreign table",
  										inh->relname)));
  					for (count = 0; count < rel->rd_att->natts; count++)
  					{
  						Form_pg_attribute inhattr = TupleDescAttr(rel->rd_att,
  																  count);
  						char	   *inhname = NameStr(inhattr->attname);
  
  						if (inhattr->attisdropped)
  							continue;
  						if (strcmp(key, inhname) == 0)
  						{
  							found = true;
  
  							/*
  							 * It's tempting to set forced_not_null if the
  							 * parent column is already NOT NULL, but that
  							 * seems unsafe because the column's NOT NULL
  							 * marking might disappear between now and
  							 * execution.  Do the runtime check to be safe.
  							 */
  							break;
  						}
  					}
  					table_close(rel, NoLock);
  					if (found)
  						break;
  				}
  			}
  
  			/*
  			 * In the ALTER TABLE case, don't complain about index keys not
  			 * created in the command; they may well exist already.
  			 * DefineIndex will complain about them if not.
  			 */
  			if (!found && !cxt->isalter)
  				ereport(ERROR,
  						(errcode(ERRCODE_UNDEFINED_COLUMN),
  						 errmsg("column \"%s\" named in key does not exist", key),
  						 parser_errposition(cxt->pstate, constraint->location)));
  
  			/* Check for PRIMARY KEY(foo, foo) */
  			foreach(columns, index->indexParams)
  			{
  				iparam = (IndexElem *) lfirst(columns);
  				if (iparam->name && strcmp(key, iparam->name) == 0)
  				{
  					if (index->primary)
  						ereport(ERROR,
  								(errcode(ERRCODE_DUPLICATE_COLUMN),
  								 errmsg("column \"%s\" appears twice in primary key constraint",
  										key),
  								 parser_errposition(cxt->pstate, constraint->location)));
  					else
  						ereport(ERROR,
  								(errcode(ERRCODE_DUPLICATE_COLUMN),
  								 errmsg("column \"%s\" appears twice in unique constraint",
  										key),
  								 parser_errposition(cxt->pstate, constraint->location)));
  				}
  			}
  
  			/* OK, add it to the index definition */
  			iparam = makeNode(IndexElem);
  			iparam->name = pstrdup(key);
  			iparam->expr = NULL;
  			iparam->indexcolname = NULL;
  			iparam->collation = NIL;
  			iparam->opclass = NIL;
  			iparam->ordering = SORTBY_DEFAULT;
  			iparam->nulls_ordering = SORTBY_NULLS_DEFAULT;
  			index->indexParams = lappend(index->indexParams, iparam);
  
  			/*
  			 * For a primary-key column, also create an item for ALTER TABLE
  			 * SET NOT NULL if we couldn't ensure it via is_not_null above.
  			 */
  			if (constraint->contype == CONSTR_PRIMARY && !forced_not_null)
  			{
  				AlterTableCmd *notnullcmd = makeNode(AlterTableCmd);
  
  				notnullcmd->subtype = AT_SetNotNull;
  				notnullcmd->name = pstrdup(key);
  				notnullcmds = lappend(notnullcmds, notnullcmd);
  			}
  		}
  	}
  
  	/*
  	 * Add included columns to index definition.  This is much like the
  	 * simple-column-name-list code above, except that we don't worry about
  	 * NOT NULL marking; included columns in a primary key should not be
  	 * forced NOT NULL.  We don't complain about duplicate columns, either,
  	 * though maybe we should?
  	 */
  	foreach(lc, constraint->including)
  	{
  		char	   *key = strVal(lfirst(lc));
  		bool		found = false;
  		ColumnDef  *column = NULL;
  		ListCell   *columns;
  		IndexElem  *iparam;
  
  		foreach(columns, cxt->columns)
  		{
  			column = lfirst_node(ColumnDef, columns);
  			if (strcmp(column->colname, key) == 0)
  			{
  				found = true;
  				break;
  			}
  		}
  
  		if (!found)
  		{
  			if (SystemAttributeByName(key) != NULL)
  			{
  				/*
  				 * column will be a system column in the new table, so accept
  				 * it.
  				 */
  				found = true;
  			}
  			else if (cxt->inhRelations)
  			{
  				/* try inherited tables */
  				ListCell   *inher;
  
  				foreach(inher, cxt->inhRelations)
  				{
  					RangeVar   *inh = lfirst_node(RangeVar, inher);
  					Relation	rel;
  					int			count;
  
  					rel = table_openrv(inh, AccessShareLock);
  					/* check user requested inheritance from valid relkind */
  					if (rel->rd_rel->relkind != RELKIND_RELATION &&
  						rel->rd_rel->relkind != RELKIND_FOREIGN_TABLE &&
  						rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
  						ereport(ERROR,
  								(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  								 errmsg("inherited relation \"%s\" is not a table or foreign table",
  										inh->relname)));
  					for (count = 0; count < rel->rd_att->natts; count++)
  					{
  						Form_pg_attribute inhattr = TupleDescAttr(rel->rd_att,
  																  count);
  						char	   *inhname = NameStr(inhattr->attname);
  
  						if (inhattr->attisdropped)
  							continue;
  						if (strcmp(key, inhname) == 0)
  						{
  							found = true;
  							break;
  						}
  					}
  					table_close(rel, NoLock);
  					if (found)
  						break;
  				}
  			}
  		}
  
  		/*
  		 * In the ALTER TABLE case, don't complain about index keys not
  		 * created in the command; they may well exist already. DefineIndex
  		 * will complain about them if not.
  		 */
  		if (!found && !cxt->isalter)
  			ereport(ERROR,
  					(errcode(ERRCODE_UNDEFINED_COLUMN),
  					 errmsg("column \"%s\" named in key does not exist", key),
  					 parser_errposition(cxt->pstate, constraint->location)));
  
  		/* OK, add it to the index definition */
  		iparam = makeNode(IndexElem);
  		iparam->name = pstrdup(key);
  		iparam->expr = NULL;
  		iparam->indexcolname = NULL;
  		iparam->collation = NIL;
  		iparam->opclass = NIL;
  		index->indexIncludingParams = lappend(index->indexIncludingParams, iparam);
  	}
  
  	/*
  	 * If we found anything that requires run-time SET NOT NULL, build a full
  	 * ALTER TABLE command for that and add it to cxt->alist.
  	 */
  	if (notnullcmds)
  	{
  		AlterTableStmt *alterstmt = makeNode(AlterTableStmt);
  
  		alterstmt->relation = copyObject(cxt->relation);
  		alterstmt->cmds = notnullcmds;
  		alterstmt->relkind = OBJECT_TABLE;
  		alterstmt->missing_ok = false;
  
  		cxt->alist = lappend(cxt->alist, alterstmt);
  	}
  
  	return index;
  }
  
  /*
   * transformExtendedStatistics
   *     Handle extended statistic objects
   *
   * Right now, there's nothing to do here, so we just append the list to
   * the existing "after" list.
   */
  static void
  transformExtendedStatistics(CreateStmtContext *cxt)
  {
  	cxt->alist = list_concat(cxt->alist, cxt->extstats);
  }
  
  /*
   * transformCheckConstraints
   *		handle CHECK constraints
   *
   * Right now, there's nothing to do here when called from ALTER TABLE,
   * but the other constraint-transformation functions are called in both
   * the CREATE TABLE and ALTER TABLE paths, so do the same here, and just
   * don't do anything if we're not authorized to skip validation.
   */
  static void
  transformCheckConstraints(CreateStmtContext *cxt, bool skipValidation)
  {
  	ListCell   *ckclist;
  
  	if (cxt->ckconstraints == NIL)
  		return;
  
  	/*
  	 * If creating a new table (but not a foreign table), we can safely skip
  	 * validation of check constraints, and nonetheless mark them valid. (This
  	 * will override any user-supplied NOT VALID flag.)
  	 */
  	if (skipValidation)
  	{
  		foreach(ckclist, cxt->ckconstraints)
  		{
  			Constraint *constraint = (Constraint *) lfirst(ckclist);
  
  			constraint->skip_validation = true;
  			constraint->initially_valid = true;
  		}
  	}
  }
  
  /*
   * transformFKConstraints
   *		handle FOREIGN KEY constraints
   */
  static void
  transformFKConstraints(CreateStmtContext *cxt,
  					   bool skipValidation, bool isAddConstraint)
  {
  	ListCell   *fkclist;
  
  	if (cxt->fkconstraints == NIL)
  		return;
  
  	/*
  	 * If CREATE TABLE or adding a column with NULL default, we can safely
  	 * skip validation of FK constraints, and nonetheless mark them valid.
  	 * (This will override any user-supplied NOT VALID flag.)
  	 */
  	if (skipValidation)
  	{
  		foreach(fkclist, cxt->fkconstraints)
  		{
  			Constraint *constraint = (Constraint *) lfirst(fkclist);
  
  			constraint->skip_validation = true;
  			constraint->initially_valid = true;
  		}
  	}
  
  	/*
  	 * For CREATE TABLE or ALTER TABLE ADD COLUMN, gin up an ALTER TABLE ADD
  	 * CONSTRAINT command to execute after the basic command is complete. (If
  	 * called from ADD CONSTRAINT, that routine will add the FK constraints to
  	 * its own subcommand list.)
  	 *
  	 * Note: the ADD CONSTRAINT command must also execute after any index
  	 * creation commands.  Thus, this should run after
  	 * transformIndexConstraints, so that the CREATE INDEX commands are
  	 * already in cxt->alist.
  	 */
  	if (!isAddConstraint)
  	{
  		AlterTableStmt *alterstmt = makeNode(AlterTableStmt);
  
  		alterstmt->relation = cxt->relation;
  		alterstmt->cmds = NIL;
  		alterstmt->relkind = OBJECT_TABLE;
  
  		foreach(fkclist, cxt->fkconstraints)
  		{
  			Constraint *constraint = (Constraint *) lfirst(fkclist);
  			AlterTableCmd *altercmd = makeNode(AlterTableCmd);
  
  			altercmd->subtype = AT_ProcessedConstraint;
  			altercmd->name = NULL;
  			altercmd->def = (Node *) constraint;
  			alterstmt->cmds = lappend(alterstmt->cmds, altercmd);
  		}
  
  		cxt->alist = lappend(cxt->alist, alterstmt);
  	}
  }
  
  /*
   * transformIndexStmt - parse analysis for CREATE INDEX and ALTER TABLE
   *
   * Note: this is a no-op for an index not using either index expressions or
   * a predicate expression.  There are several code paths that create indexes
   * without bothering to call this, because they know they don't have any
   * such expressions to deal with.
   *
   * To avoid race conditions, it's important that this function rely only on
   * the passed-in relid (and not on stmt->relation) to determine the target
   * relation.
   */
  IndexStmt *
  transformIndexStmt(Oid relid, IndexStmt *stmt, const char *queryString)
  {
  	ParseState *pstate;
  	RangeTblEntry *rte;
  	ListCell   *l;
  	Relation	rel;
  
  	/* Nothing to do if statement already transformed. */
  	if (stmt->transformed)
  		return stmt;
  
  	/*
  	 * We must not scribble on the passed-in IndexStmt, so copy it.  (This is
  	 * overkill, but easy.)
  	 */
  	stmt = copyObject(stmt);
  
  	/* Set up pstate */
  	pstate = make_parsestate(NULL);
  	pstate->p_sourcetext = queryString;
  
  	/*
  	 * Put the parent table into the rtable so that the expressions can refer
  	 * to its fields without qualification.  Caller is responsible for locking
  	 * relation, but we still need to open it.
  	 */
  	rel = relation_open(relid, NoLock);
  	rte = addRangeTableEntryForRelation(pstate, rel,
  										AccessShareLock,
  										NULL, false, true);
  
  	/* no to join list, yes to namespaces */
  	addRTEtoQuery(pstate, rte, false, true, true);
  
  	/* take care of the where clause */
  	if (stmt->whereClause)
  	{
  		stmt->whereClause = transformWhereClause(pstate,
  												 stmt->whereClause,
  												 EXPR_KIND_INDEX_PREDICATE,
  												 "WHERE");
  		/* we have to fix its collations too */
  		assign_expr_collations(pstate, stmt->whereClause);
  	}
  
  	/* take care of any index expressions */
  	foreach(l, stmt->indexParams)
  	{
  		IndexElem  *ielem = (IndexElem *) lfirst(l);
  
  		if (ielem->expr)
  		{
  			/* Extract preliminary index col name before transforming expr */
  			if (ielem->indexcolname == NULL)
  				ielem->indexcolname = FigureIndexColname(ielem->expr);
  
  			/* Now do parse transformation of the expression */
  			ielem->expr = transformExpr(pstate, ielem->expr,
  										EXPR_KIND_INDEX_EXPRESSION);
  
  			/* We have to fix its collations too */
  			assign_expr_collations(pstate, ielem->expr);
  
  			/*
  			 * transformExpr() should have already rejected subqueries,
  			 * aggregates, window functions, and SRFs, based on the EXPR_KIND_
  			 * for an index expression.
  			 *
  			 * DefineIndex() will make more checks.
  			 */
  		}
  	}
  
  	/*
  	 * Check that only the base rel is mentioned.  (This should be dead code
  	 * now that add_missing_from is history.)
  	 */
  	if (list_length(pstate->p_rtable) != 1)
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
  				 errmsg("index expressions and predicates can refer only to the table being indexed")));
  
  	free_parsestate(pstate);
  
  	/* Close relation */
  	table_close(rel, NoLock);
  
  	/* Mark statement as successfully transformed */
  	stmt->transformed = true;
  
  	return stmt;
  }
  
  
  /*
   * transformRuleStmt -
   *	  transform a CREATE RULE Statement. The action is a list of parse
   *	  trees which is transformed into a list of query trees, and we also
   *	  transform the WHERE clause if any.
   *
   * actions and whereClause are output parameters that receive the
   * transformed results.
   *
   * Note that we must not scribble on the passed-in RuleStmt, so we do
   * copyObject() on the actions and WHERE clause.
   */
  void
  transformRuleStmt(RuleStmt *stmt, const char *queryString,
  				  List **actions, Node **whereClause)
  {
  	Relation	rel;
  	ParseState *pstate;
  	RangeTblEntry *oldrte;
  	RangeTblEntry *newrte;
  
  	/*
  	 * To avoid deadlock, make sure the first thing we do is grab
  	 * AccessExclusiveLock on the target relation.  This will be needed by
  	 * DefineQueryRewrite(), and we don't want to grab a lesser lock
  	 * beforehand.
  	 */
  	rel = table_openrv(stmt->relation, AccessExclusiveLock);
  
  	if (rel->rd_rel->relkind == RELKIND_MATVIEW)
  		ereport(ERROR,
  				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  				 errmsg("rules on materialized views are not supported")));
  
  	/* Set up pstate */
  	pstate = make_parsestate(NULL);
  	pstate->p_sourcetext = queryString;
  
  	/*
  	 * NOTE: 'OLD' must always have a varno equal to 1 and 'NEW' equal to 2.
  	 * Set up their RTEs in the main pstate for use in parsing the rule
  	 * qualification.
  	 */
  	oldrte = addRangeTableEntryForRelation(pstate, rel,
  										   AccessShareLock,
  										   makeAlias("old", NIL),
  										   false, false);
  	newrte = addRangeTableEntryForRelation(pstate, rel,
  										   AccessShareLock,
  										   makeAlias("new", NIL),
  										   false, false);
  	/* Must override addRangeTableEntry's default access-check flags */
  	oldrte->requiredPerms = 0;
  	newrte->requiredPerms = 0;
  
  	/*
  	 * They must be in the namespace too for lookup purposes, but only add the
  	 * one(s) that are relevant for the current kind of rule.  In an UPDATE
  	 * rule, quals must refer to OLD.field or NEW.field to be unambiguous, but
  	 * there's no need to be so picky for INSERT & DELETE.  We do not add them
  	 * to the joinlist.
  	 */
  	switch (stmt->event)
  	{
  		case CMD_SELECT:
  			addRTEtoQuery(pstate, oldrte, false, true, true);
  			break;
  		case CMD_UPDATE:
  			addRTEtoQuery(pstate, oldrte, false, true, true);
  			addRTEtoQuery(pstate, newrte, false, true, true);
  			break;
  		case CMD_INSERT:
  			addRTEtoQuery(pstate, newrte, false, true, true);
  			break;
  		case CMD_DELETE:
  			addRTEtoQuery(pstate, oldrte, false, true, true);
  			break;
  		default:
  			elog(ERROR, "unrecognized event type: %d",
  				 (int) stmt->event);
  			break;
  	}
  
  	/* take care of the where clause */
  	*whereClause = transformWhereClause(pstate,
  										(Node *) copyObject(stmt->whereClause),
  										EXPR_KIND_WHERE,
  										"WHERE");
  	/* we have to fix its collations too */
  	assign_expr_collations(pstate, *whereClause);
  
  	/* this is probably dead code without add_missing_from: */
  	if (list_length(pstate->p_rtable) != 2) /* naughty, naughty... */
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
  				 errmsg("rule WHERE condition cannot contain references to other relations")));
  
  	/*
  	 * 'instead nothing' rules with a qualification need a query rangetable so
  	 * the rewrite handler can add the negated rule qualification to the
  	 * original query. We create a query with the new command type CMD_NOTHING
  	 * here that is treated specially by the rewrite system.
  	 */
  	if (stmt->actions == NIL)
  	{
  		Query	   *nothing_qry = makeNode(Query);
  
  		nothing_qry->commandType = CMD_NOTHING;
  		nothing_qry->rtable = pstate->p_rtable;
  		nothing_qry->jointree = makeFromExpr(NIL, NULL);	/* no join wanted */
  
  		*actions = list_make1(nothing_qry);
  	}
  	else
  	{
  		ListCell   *l;
  		List	   *newactions = NIL;
  
  		/*
  		 * transform each statement, like parse_sub_analyze()
  		 */
  		foreach(l, stmt->actions)
  		{
  			Node	   *action = (Node *) lfirst(l);
  			ParseState *sub_pstate = make_parsestate(NULL);
  			Query	   *sub_qry,
  					   *top_subqry;
  			bool		has_old,
  						has_new;
  
  			/*
  			 * Since outer ParseState isn't parent of inner, have to pass down
  			 * the query text by hand.
  			 */
  			sub_pstate->p_sourcetext = queryString;
  
  			/*
  			 * Set up OLD/NEW in the rtable for this statement.  The entries
  			 * are added only to relnamespace, not varnamespace, because we
  			 * don't want them to be referred to by unqualified field names
  			 * nor "*" in the rule actions.  We decide later whether to put
  			 * them in the joinlist.
  			 */
  			oldrte = addRangeTableEntryForRelation(sub_pstate, rel,
  												   AccessShareLock,
  												   makeAlias("old", NIL),
  												   false, false);
  			newrte = addRangeTableEntryForRelation(sub_pstate, rel,
  												   AccessShareLock,
  												   makeAlias("new", NIL),
  												   false, false);
  			oldrte->requiredPerms = 0;
  			newrte->requiredPerms = 0;
  			addRTEtoQuery(sub_pstate, oldrte, false, true, false);
  			addRTEtoQuery(sub_pstate, newrte, false, true, false);
  
  			/* Transform the rule action statement */
  			top_subqry = transformStmt(sub_pstate,
  									   (Node *) copyObject(action));
  
  			/*
  			 * We cannot support utility-statement actions (eg NOTIFY) with
  			 * nonempty rule WHERE conditions, because there's no way to make
  			 * the utility action execute conditionally.
  			 */
  			if (top_subqry->commandType == CMD_UTILITY &&
  				*whereClause != NULL)
  				ereport(ERROR,
  						(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
  						 errmsg("rules with WHERE conditions can only have SELECT, INSERT, UPDATE, or DELETE actions")));
  
  			/*
  			 * If the action is INSERT...SELECT, OLD/NEW have been pushed down
  			 * into the SELECT, and that's what we need to look at. (Ugly
  			 * kluge ... try to fix this when we redesign querytrees.)
  			 */
  			sub_qry = getInsertSelectQuery(top_subqry, NULL);
  
  			/*
  			 * If the sub_qry is a setop, we cannot attach any qualifications
  			 * to it, because the planner won't notice them.  This could
  			 * perhaps be relaxed someday, but for now, we may as well reject
  			 * such a rule immediately.
  			 */
  			if (sub_qry->setOperations != NULL && *whereClause != NULL)
  				ereport(ERROR,
  						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  						 errmsg("conditional UNION/INTERSECT/EXCEPT statements are not implemented")));
  
  			/*
  			 * Validate action's use of OLD/NEW, qual too
  			 */
  			has_old =
  				rangeTableEntry_used((Node *) sub_qry, PRS2_OLD_VARNO, 0) ||
  				rangeTableEntry_used(*whereClause, PRS2_OLD_VARNO, 0);
  			has_new =
  				rangeTableEntry_used((Node *) sub_qry, PRS2_NEW_VARNO, 0) ||
  				rangeTableEntry_used(*whereClause, PRS2_NEW_VARNO, 0);
  
  			switch (stmt->event)
  			{
  				case CMD_SELECT:
  					if (has_old)
  						ereport(ERROR,
  								(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
  								 errmsg("ON SELECT rule cannot use OLD")));
  					if (has_new)
  						ereport(ERROR,
  								(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
  								 errmsg("ON SELECT rule cannot use NEW")));
  					break;
  				case CMD_UPDATE:
  					/* both are OK */
  					break;
  				case CMD_INSERT:
  					if (has_old)
  						ereport(ERROR,
  								(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
  								 errmsg("ON INSERT rule cannot use OLD")));
  					break;
  				case CMD_DELETE:
  					if (has_new)
  						ereport(ERROR,
  								(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
  								 errmsg("ON DELETE rule cannot use NEW")));
  					break;
  				default:
  					elog(ERROR, "unrecognized event type: %d",
  						 (int) stmt->event);
  					break;
  			}
  
  			/*
  			 * OLD/NEW are not allowed in WITH queries, because they would
  			 * amount to outer references for the WITH, which we disallow.
  			 * However, they were already in the outer rangetable when we
  			 * analyzed the query, so we have to check.
  			 *
  			 * Note that in the INSERT...SELECT case, we need to examine the
  			 * CTE lists of both top_subqry and sub_qry.
  			 *
  			 * Note that we aren't digging into the body of the query looking
  			 * for WITHs in nested sub-SELECTs.  A WITH down there can
  			 * legitimately refer to OLD/NEW, because it'd be an
  			 * indirect-correlated outer reference.
  			 */
  			if (rangeTableEntry_used((Node *) top_subqry->cteList,
  									 PRS2_OLD_VARNO, 0) ||
  				rangeTableEntry_used((Node *) sub_qry->cteList,
  									 PRS2_OLD_VARNO, 0))
  				ereport(ERROR,
  						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  						 errmsg("cannot refer to OLD within WITH query")));
  			if (rangeTableEntry_used((Node *) top_subqry->cteList,
  									 PRS2_NEW_VARNO, 0) ||
  				rangeTableEntry_used((Node *) sub_qry->cteList,
  									 PRS2_NEW_VARNO, 0))
  				ereport(ERROR,
  						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  						 errmsg("cannot refer to NEW within WITH query")));
  
  			/*
  			 * For efficiency's sake, add OLD to the rule action's jointree
  			 * only if it was actually referenced in the statement or qual.
  			 *
  			 * For INSERT, NEW is not really a relation (only a reference to
  			 * the to-be-inserted tuple) and should never be added to the
  			 * jointree.
  			 *
  			 * For UPDATE, we treat NEW as being another kind of reference to
  			 * OLD, because it represents references to *transformed* tuples
  			 * of the existing relation.  It would be wrong to enter NEW
  			 * separately in the jointree, since that would cause a double
  			 * join of the updated relation.  It's also wrong to fail to make
  			 * a jointree entry if only NEW and not OLD is mentioned.
  			 */
  			if (has_old || (has_new && stmt->event == CMD_UPDATE))
  			{
  				/*
  				 * If sub_qry is a setop, manipulating its jointree will do no
  				 * good at all, because the jointree is dummy. (This should be
  				 * a can't-happen case because of prior tests.)
  				 */
  				if (sub_qry->setOperations != NULL)
  					ereport(ERROR,
  							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  							 errmsg("conditional UNION/INTERSECT/EXCEPT statements are not implemented")));
  				/* hack so we can use addRTEtoQuery() */
  				sub_pstate->p_rtable = sub_qry->rtable;
  				sub_pstate->p_joinlist = sub_qry->jointree->fromlist;
  				addRTEtoQuery(sub_pstate, oldrte, true, false, false);
  				sub_qry->jointree->fromlist = sub_pstate->p_joinlist;
  			}
  
  			newactions = lappend(newactions, top_subqry);
  
  			free_parsestate(sub_pstate);
  		}
  
  		*actions = newactions;
  	}
  
  	free_parsestate(pstate);
  
  	/* Close relation, but keep the exclusive lock */
  	table_close(rel, NoLock);
  }
  
  
  /*
   * transformAlterTableStmt -
   *		parse analysis for ALTER TABLE
   *
   * Returns a List of utility commands to be done in sequence.  One of these
   * will be the transformed AlterTableStmt, but there may be additional actions
   * to be done before and after the actual AlterTable() call.
   *
   * To avoid race conditions, it's important that this function rely only on
   * the passed-in relid (and not on stmt->relation) to determine the target
   * relation.
   */
  List *
  transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
  						const char *queryString)
  {
  	Relation	rel;
  	TupleDesc	tupdesc;
  	ParseState *pstate;
  	CreateStmtContext cxt;
  	List	   *result;
  	List	   *save_alist;
  	ListCell   *lcmd,
  			   *l;
  	List	   *newcmds = NIL;
  	bool		skipValidation = true;
  	AlterTableCmd *newcmd;
  	RangeTblEntry *rte;
  
  	/*
  	 * We must not scribble on the passed-in AlterTableStmt, so copy it. (This
  	 * is overkill, but easy.)
  	 */
  	stmt = copyObject(stmt);
  
  	/* Caller is responsible for locking the relation */
  	rel = relation_open(relid, NoLock);
  	tupdesc = RelationGetDescr(rel);
  
  	/* Set up pstate */
  	pstate = make_parsestate(NULL);
  	pstate->p_sourcetext = queryString;
  	rte = addRangeTableEntryForRelation(pstate,
  										rel,
  										AccessShareLock,
  										NULL,
  										false,
  										true);
  	addRTEtoQuery(pstate, rte, false, true, true);
  
  	/* Set up CreateStmtContext */
  	cxt.pstate = pstate;
  	if (stmt->relkind == OBJECT_FOREIGN_TABLE)
  	{
  		cxt.stmtType = "ALTER FOREIGN TABLE";
  		cxt.isforeign = true;
  	}
  	else
  	{
  		cxt.stmtType = "ALTER TABLE";
  		cxt.isforeign = false;
  	}
  	cxt.relation = stmt->relation;
  	cxt.rel = rel;
  	cxt.inhRelations = NIL;
  	cxt.isalter = true;
  	cxt.columns = NIL;
  	cxt.ckconstraints = NIL;
  	cxt.fkconstraints = NIL;
  	cxt.ixconstraints = NIL;
  	cxt.inh_indexes = NIL;
  	cxt.extstats = NIL;
  	cxt.blist = NIL;
  	cxt.alist = NIL;
  	cxt.pkey = NULL;
  	cxt.ispartitioned = (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE);
  	cxt.partbound = NULL;
  	cxt.ofType = false;
  
  	/*
  	 * The only subtypes that currently require parse transformation handling
  	 * are ADD COLUMN, ADD CONSTRAINT and SET DATA TYPE.  These largely re-use
  	 * code from CREATE TABLE.
  	 */
  	foreach(lcmd, stmt->cmds)
  	{
  		AlterTableCmd *cmd = (AlterTableCmd *) lfirst(lcmd);
  
  		switch (cmd->subtype)
  		{
  			case AT_AddColumn:
  			case AT_AddColumnToView:
  				{
  					ColumnDef  *def = castNode(ColumnDef, cmd->def);
  
  					transformColumnDefinition(&cxt, def);
  
  					/*
  					 * If the column has a non-null default, we can't skip
  					 * validation of foreign keys.
  					 */
  					if (def->raw_default != NULL)
  						skipValidation = false;
  
  					/*
  					 * All constraints are processed in other ways. Remove the
  					 * original list
  					 */
  					def->constraints = NIL;
  
  					newcmds = lappend(newcmds, cmd);
  					break;
  				}
  
  			case AT_AddConstraint:
  
  				/*
  				 * The original AddConstraint cmd node doesn't go to newcmds
  				 */
  				if (IsA(cmd->def, Constraint))
  				{
  					transformTableConstraint(&cxt, (Constraint *) cmd->def);
  					if (((Constraint *) cmd->def)->contype == CONSTR_FOREIGN)
  						skipValidation = false;
  				}
  				else
  					elog(ERROR, "unrecognized node type: %d",
  						 (int) nodeTag(cmd->def));
  				break;
  
  			case AT_ProcessedConstraint:
  
  				/*
  				 * Already-transformed ADD CONSTRAINT, so just make it look
  				 * like the standard case.
  				 */
  				cmd->subtype = AT_AddConstraint;
  				newcmds = lappend(newcmds, cmd);
  				break;
  
  			case AT_AlterColumnType:
  				{
  					ColumnDef  *def = (ColumnDef *) cmd->def;
  					AttrNumber	attnum;
  
  					/*
  					 * For ALTER COLUMN TYPE, transform the USING clause if
  					 * one was specified.
  					 */
  					if (def->raw_default)
  					{
  						def->cooked_default =
  							transformExpr(pstate, def->raw_default,
  										  EXPR_KIND_ALTER_COL_TRANSFORM);
  					}
  
  					/*
  					 * For identity column, create ALTER SEQUENCE command to
  					 * change the data type of the sequence.
  					 */
  					attnum = get_attnum(relid, cmd->name);
  
  					/*
  					 * if attribute not found, something will error about it
  					 * later
  					 */
  					if (attnum != InvalidAttrNumber &&
  						TupleDescAttr(tupdesc, attnum - 1)->attidentity)
  					{
  						Oid			seq_relid = getIdentitySequence(relid, attnum, false);
  						Oid			typeOid = typenameTypeId(pstate, def->typeName);
  						AlterSeqStmt *altseqstmt = makeNode(AlterSeqStmt);
  
  						altseqstmt->sequence = makeRangeVar(get_namespace_name(get_rel_namespace(seq_relid)),
  															get_rel_name(seq_relid),
  															-1);
  						altseqstmt->options = list_make1(makeDefElem("as", (Node *) makeTypeNameFromOid(typeOid, -1), -1));
  						altseqstmt->for_identity = true;
  						cxt.blist = lappend(cxt.blist, altseqstmt);
  					}
  
  					newcmds = lappend(newcmds, cmd);
  					break;
  				}
  
  			case AT_AddIdentity:
  				{
  					Constraint *def = castNode(Constraint, cmd->def);
  					ColumnDef  *newdef = makeNode(ColumnDef);
  					AttrNumber	attnum;
  
  					newdef->colname = cmd->name;
  					newdef->identity = def->generated_when;
  					cmd->def = (Node *) newdef;
  
  					attnum = get_attnum(relid, cmd->name);
  
  					/*
  					 * if attribute not found, something will error about it
  					 * later
  					 */
  					if (attnum != InvalidAttrNumber)
  						generateSerialExtraStmts(&cxt, newdef,
  												 get_atttype(relid, attnum),
  												 def->options, true,
  												 NULL, NULL);
  
  					newcmds = lappend(newcmds, cmd);
  					break;
  				}
  
  			case AT_SetIdentity:
  				{
  					/*
  					 * Create an ALTER SEQUENCE statement for the internal
  					 * sequence of the identity column.
  					 */
  					ListCell   *lc;
  					List	   *newseqopts = NIL;
  					List	   *newdef = NIL;
  					AttrNumber	attnum;
  
  					/*
  					 * Split options into those handled by ALTER SEQUENCE and
  					 * those for ALTER TABLE proper.
  					 */
  					foreach(lc, castNode(List, cmd->def))
  					{
  						DefElem    *def = lfirst_node(DefElem, lc);
  
  						if (strcmp(def->defname, "generated") == 0)
  							newdef = lappend(newdef, def);
  						else
  							newseqopts = lappend(newseqopts, def);
  					}
  
  					attnum = get_attnum(relid, cmd->name);
  
  					if (attnum)
  					{
  						Oid			seq_relid = getIdentitySequence(relid, attnum, true);
  
  						if (seq_relid)
  						{
  							AlterSeqStmt *seqstmt;
  
  							seqstmt = makeNode(AlterSeqStmt);
  							seqstmt->sequence = makeRangeVar(get_namespace_name(get_rel_namespace(seq_relid)),
  															 get_rel_name(seq_relid), -1);
  							seqstmt->options = newseqopts;
  							seqstmt->for_identity = true;
  							seqstmt->missing_ok = false;
  
  							cxt.alist = lappend(cxt.alist, seqstmt);
  						}
  					}
  
  					/*
  					 * If column was not found or was not an identity column,
  					 * we just let the ALTER TABLE command error out later.
  					 */
  
  					cmd->def = (Node *) newdef;
  					newcmds = lappend(newcmds, cmd);
  					break;
  				}
  
  			case AT_AttachPartition:
  			case AT_DetachPartition:
  				{
  					PartitionCmd *partcmd = (PartitionCmd *) cmd->def;
  
  					transformPartitionCmd(&cxt, partcmd);
  					/* assign transformed value of the partition bound */
  					partcmd->bound = cxt.partbound;
  				}
  
  				newcmds = lappend(newcmds, cmd);
  				break;
  
  			default:
  				newcmds = lappend(newcmds, cmd);
  				break;
  		}
  	}
  
  	/*
  	 * Transfer anything we already have in cxt.alist into save_alist, to keep
  	 * it separate from the output of transformIndexConstraints.
  	 */
  	save_alist = cxt.alist;
  	cxt.alist = NIL;
  
  	/* Postprocess constraints */
  	transformIndexConstraints(&cxt);
  	transformFKConstraints(&cxt, skipValidation, true);
  	transformCheckConstraints(&cxt, false);
  
  	/*
  	 * Push any index-creation commands into the ALTER, so that they can be
  	 * scheduled nicely by tablecmds.c.  Note that tablecmds.c assumes that
  	 * the IndexStmt attached to an AT_AddIndex or AT_AddIndexConstraint
  	 * subcommand has already been through transformIndexStmt.
  	 */
  	foreach(l, cxt.alist)
  	{
  		Node	   *istmt = (Node *) lfirst(l);
  
  		/*
  		 * We assume here that cxt.alist contains only IndexStmts and possibly
  		 * ALTER TABLE SET NOT NULL statements generated from primary key
  		 * constraints.  We absorb the subcommands of the latter directly.
  		 */
  		if (IsA(istmt, IndexStmt))
  		{
  			IndexStmt  *idxstmt = (IndexStmt *) istmt;
  
  			idxstmt = transformIndexStmt(relid, idxstmt, queryString);
  			newcmd = makeNode(AlterTableCmd);
  			newcmd->subtype = OidIsValid(idxstmt->indexOid) ? AT_AddIndexConstraint : AT_AddIndex;
  			newcmd->def = (Node *) idxstmt;
  			newcmds = lappend(newcmds, newcmd);
  		}
  		else if (IsA(istmt, AlterTableStmt))
  		{
  			AlterTableStmt *alterstmt = (AlterTableStmt *) istmt;
  
  			newcmds = list_concat(newcmds, alterstmt->cmds);
  		}
  		else
  			elog(ERROR, "unexpected stmt type %d", (int) nodeTag(istmt));
  	}
  	cxt.alist = NIL;
  
  	/* Append any CHECK or FK constraints to the commands list */
  	foreach(l, cxt.ckconstraints)
  	{
  		newcmd = makeNode(AlterTableCmd);
  		newcmd->subtype = AT_AddConstraint;
  		newcmd->def = (Node *) lfirst(l);
  		newcmds = lappend(newcmds, newcmd);
  	}
  	foreach(l, cxt.fkconstraints)
  	{
  		newcmd = makeNode(AlterTableCmd);
  		newcmd->subtype = AT_AddConstraint;
  		newcmd->def = (Node *) lfirst(l);
  		newcmds = lappend(newcmds, newcmd);
  	}
  
  	/* Append extended statistic objects */
  	transformExtendedStatistics(&cxt);
  
  	/* Close rel */
  	relation_close(rel, NoLock);
  
  	/*
  	 * Output results.
  	 */
  	stmt->cmds = newcmds;
  
  	result = lappend(cxt.blist, stmt);
  	result = list_concat(result, cxt.alist);
  	result = list_concat(result, save_alist);
  
  	return result;
  }
  
  
  /*
   * Preprocess a list of column constraint clauses
   * to attach constraint attributes to their primary constraint nodes
   * and detect inconsistent/misplaced constraint attributes.
   *
   * NOTE: currently, attributes are only supported for FOREIGN KEY, UNIQUE,
   * EXCLUSION, and PRIMARY KEY constraints, but someday they ought to be
   * supported for other constraint types.
   */
  static void
  transformConstraintAttrs(CreateStmtContext *cxt, List *constraintList)
  {
  	Constraint *lastprimarycon = NULL;
  	bool		saw_deferrability = false;
  	bool		saw_initially = false;
  	ListCell   *clist;
  
  #define SUPPORTS_ATTRS(node)				\
  	((node) != NULL &&						\
  	 ((node)->contype == CONSTR_PRIMARY ||	\
  	  (node)->contype == CONSTR_UNIQUE ||	\
  	  (node)->contype == CONSTR_EXCLUSION || \
  	  (node)->contype == CONSTR_FOREIGN))
  
  	foreach(clist, constraintList)
  	{
  		Constraint *con = (Constraint *) lfirst(clist);
  
  		if (!IsA(con, Constraint))
  			elog(ERROR, "unrecognized node type: %d",
  				 (int) nodeTag(con));
  		switch (con->contype)
  		{
  			case CONSTR_ATTR_DEFERRABLE:
  				if (!SUPPORTS_ATTRS(lastprimarycon))
  					ereport(ERROR,
  							(errcode(ERRCODE_SYNTAX_ERROR),
  							 errmsg("misplaced DEFERRABLE clause"),
  							 parser_errposition(cxt->pstate, con->location)));
  				if (saw_deferrability)
  					ereport(ERROR,
  							(errcode(ERRCODE_SYNTAX_ERROR),
  							 errmsg("multiple DEFERRABLE/NOT DEFERRABLE clauses not allowed"),
  							 parser_errposition(cxt->pstate, con->location)));
  				saw_deferrability = true;
  				lastprimarycon->deferrable = true;
  				break;
  
  			case CONSTR_ATTR_NOT_DEFERRABLE:
  				if (!SUPPORTS_ATTRS(lastprimarycon))
  					ereport(ERROR,
  							(errcode(ERRCODE_SYNTAX_ERROR),
  							 errmsg("misplaced NOT DEFERRABLE clause"),
  							 parser_errposition(cxt->pstate, con->location)));
  				if (saw_deferrability)
  					ereport(ERROR,
  							(errcode(ERRCODE_SYNTAX_ERROR),
  							 errmsg("multiple DEFERRABLE/NOT DEFERRABLE clauses not allowed"),
  							 parser_errposition(cxt->pstate, con->location)));
  				saw_deferrability = true;
  				lastprimarycon->deferrable = false;
  				if (saw_initially &&
  					lastprimarycon->initdeferred)
  					ereport(ERROR,
  							(errcode(ERRCODE_SYNTAX_ERROR),
  							 errmsg("constraint declared INITIALLY DEFERRED must be DEFERRABLE"),
  							 parser_errposition(cxt->pstate, con->location)));
  				break;
  
  			case CONSTR_ATTR_DEFERRED:
  				if (!SUPPORTS_ATTRS(lastprimarycon))
  					ereport(ERROR,
  							(errcode(ERRCODE_SYNTAX_ERROR),
  							 errmsg("misplaced INITIALLY DEFERRED clause"),
  							 parser_errposition(cxt->pstate, con->location)));
  				if (saw_initially)
  					ereport(ERROR,
  							(errcode(ERRCODE_SYNTAX_ERROR),
  							 errmsg("multiple INITIALLY IMMEDIATE/DEFERRED clauses not allowed"),
  							 parser_errposition(cxt->pstate, con->location)));
  				saw_initially = true;
  				lastprimarycon->initdeferred = true;
  
  				/*
  				 * If only INITIALLY DEFERRED appears, assume DEFERRABLE
  				 */
  				if (!saw_deferrability)
  					lastprimarycon->deferrable = true;
  				else if (!lastprimarycon->deferrable)
  					ereport(ERROR,
  							(errcode(ERRCODE_SYNTAX_ERROR),
  							 errmsg("constraint declared INITIALLY DEFERRED must be DEFERRABLE"),
  							 parser_errposition(cxt->pstate, con->location)));
  				break;
  
  			case CONSTR_ATTR_IMMEDIATE:
  				if (!SUPPORTS_ATTRS(lastprimarycon))
  					ereport(ERROR,
  							(errcode(ERRCODE_SYNTAX_ERROR),
  							 errmsg("misplaced INITIALLY IMMEDIATE clause"),
  							 parser_errposition(cxt->pstate, con->location)));
  				if (saw_initially)
  					ereport(ERROR,
  							(errcode(ERRCODE_SYNTAX_ERROR),
  							 errmsg("multiple INITIALLY IMMEDIATE/DEFERRED clauses not allowed"),
  							 parser_errposition(cxt->pstate, con->location)));
  				saw_initially = true;
  				lastprimarycon->initdeferred = false;
  				break;
  
  			default:
  				/* Otherwise it's not an attribute */
  				lastprimarycon = con;
  				/* reset flags for new primary node */
  				saw_deferrability = false;
  				saw_initially = false;
  				break;
  		}
  	}
  }
  
  /*
   * Special handling of type definition for a column
   */
  static void
  transformColumnType(CreateStmtContext *cxt, ColumnDef *column)
  {
  	/*
  	 * All we really need to do here is verify that the type is valid,
  	 * including any collation spec that might be present.
  	 */
  	Type		ctype = typenameType(cxt->pstate, column->typeName, NULL);
  
  	if (column->collClause)
  	{
  		Form_pg_type typtup = (Form_pg_type) GETSTRUCT(ctype);
  
  		LookupCollation(cxt->pstate,
  						column->collClause->collname,
  						column->collClause->location);
  		/* Complain if COLLATE is applied to an uncollatable type */
  		if (!OidIsValid(typtup->typcollation))
  			ereport(ERROR,
  					(errcode(ERRCODE_DATATYPE_MISMATCH),
  					 errmsg("collations are not supported by type %s",
  							format_type_be(typtup->oid)),
  					 parser_errposition(cxt->pstate,
  										column->collClause->location)));
  	}
  
  	ReleaseSysCache(ctype);
  }
  
  
  /*
   * transformCreateSchemaStmt -
   *	  analyzes the CREATE SCHEMA statement
   *
   * Split the schema element list into individual commands and place
   * them in the result list in an order such that there are no forward
   * references (e.g. GRANT to a table created later in the list). Note
   * that the logic we use for determining forward references is
   * presently quite incomplete.
   *
   * SQL also allows constraints to make forward references, so thumb through
   * the table columns and move forward references to a posterior alter-table
   * command.
   *
   * The result is a list of parse nodes that still need to be analyzed ---
   * but we can't analyze the later commands until we've executed the earlier
   * ones, because of possible inter-object references.
   *
   * Note: this breaks the rules a little bit by modifying schema-name fields
   * within passed-in structs.  However, the transformation would be the same
   * if done over, so it should be all right to scribble on the input to this
   * extent.
   */
  List *
  transformCreateSchemaStmt(CreateSchemaStmt *stmt)
  {
  	CreateSchemaStmtContext cxt;
  	List	   *result;
  	ListCell   *elements;
  
  	cxt.stmtType = "CREATE SCHEMA";
  	cxt.schemaname = stmt->schemaname;
  	cxt.authrole = (RoleSpec *) stmt->authrole;
  	cxt.sequences = NIL;
  	cxt.tables = NIL;
  	cxt.views = NIL;
  	cxt.indexes = NIL;
  	cxt.triggers = NIL;
  	cxt.grants = NIL;
  
  	/*
  	 * Run through each schema element in the schema element list. Separate
  	 * statements by type, and do preliminary analysis.
  	 */
  	foreach(elements, stmt->schemaElts)
  	{
  		Node	   *element = lfirst(elements);
  
  		switch (nodeTag(element))
  		{
  			case T_CreateSeqStmt:
  				{
  					CreateSeqStmt *elp = (CreateSeqStmt *) element;
  
  					setSchemaName(cxt.schemaname, &elp->sequence->schemaname);
  					cxt.sequences = lappend(cxt.sequences, element);
  				}
  				break;
  
  			case T_CreateStmt:
  				{
  					CreateStmt *elp = (CreateStmt *) element;
  
  					setSchemaName(cxt.schemaname, &elp->relation->schemaname);
  
  					/*
  					 * XXX todo: deal with constraints
  					 */
  					cxt.tables = lappend(cxt.tables, element);
  				}
  				break;
  
  			case T_ViewStmt:
  				{
  					ViewStmt   *elp = (ViewStmt *) element;
  
  					setSchemaName(cxt.schemaname, &elp->view->schemaname);
  
  					/*
  					 * XXX todo: deal with references between views
  					 */
  					cxt.views = lappend(cxt.views, element);
  				}
  				break;
  
  			case T_IndexStmt:
  				{
  					IndexStmt  *elp = (IndexStmt *) element;
  
  					setSchemaName(cxt.schemaname, &elp->relation->schemaname);
  					cxt.indexes = lappend(cxt.indexes, element);
  				}
  				break;
  
  			case T_CreateTrigStmt:
  				{
  					CreateTrigStmt *elp = (CreateTrigStmt *) element;
  
  					setSchemaName(cxt.schemaname, &elp->relation->schemaname);
  					cxt.triggers = lappend(cxt.triggers, element);
  				}
  				break;
  
  			case T_GrantStmt:
  				cxt.grants = lappend(cxt.grants, element);
  				break;
  
  			default:
  				elog(ERROR, "unrecognized node type: %d",
  					 (int) nodeTag(element));
  		}
  	}
  
  	result = NIL;
  	result = list_concat(result, cxt.sequences);
  	result = list_concat(result, cxt.tables);
  	result = list_concat(result, cxt.views);
  	result = list_concat(result, cxt.indexes);
  	result = list_concat(result, cxt.triggers);
  	result = list_concat(result, cxt.grants);
  
  	return result;
  }
  
  /*
   * setSchemaName
   *		Set or check schema name in an element of a CREATE SCHEMA command
   */
  static void
  setSchemaName(char *context_schema, char **stmt_schema_name)
  {
  	if (*stmt_schema_name == NULL)
  		*stmt_schema_name = context_schema;
  	else if (strcmp(context_schema, *stmt_schema_name) != 0)
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_SCHEMA_DEFINITION),
  				 errmsg("CREATE specifies a schema (%s) "
  						"different from the one being created (%s)",
  						*stmt_schema_name, context_schema)));
  }
  
  /*
   * transformPartitionCmd
   *		Analyze the ATTACH/DETACH PARTITION command
   *
   * In case of the ATTACH PARTITION command, cxt->partbound is set to the
   * transformed value of cmd->bound.
   */
  static void
  transformPartitionCmd(CreateStmtContext *cxt, PartitionCmd *cmd)
  {
  	Relation	parentRel = cxt->rel;
  
  	switch (parentRel->rd_rel->relkind)
  	{
  		case RELKIND_PARTITIONED_TABLE:
  			/* transform the partition bound, if any */
  			Assert(RelationGetPartitionKey(parentRel) != NULL);
  			if (cmd->bound != NULL)
  				cxt->partbound = transformPartitionBound(cxt->pstate, parentRel,
  														 cmd->bound);
  			break;
  		case RELKIND_PARTITIONED_INDEX:
  			/* nothing to check */
  			Assert(cmd->bound == NULL);
  			break;
  		case RELKIND_RELATION:
  			/* the table must be partitioned */
  			ereport(ERROR,
  					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
  					 errmsg("table \"%s\" is not partitioned",
  							RelationGetRelationName(parentRel))));
  			break;
  		case RELKIND_INDEX:
  			/* the index must be partitioned */
  			ereport(ERROR,
  					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
  					 errmsg("index \"%s\" is not partitioned",
  							RelationGetRelationName(parentRel))));
  			break;
  		default:
  			/* parser shouldn't let this case through */
  			elog(ERROR, "\"%s\" is not a partitioned table or index",
  				 RelationGetRelationName(parentRel));
  			break;
  	}
  }
  
  /*
   * transformPartitionBound
   *
   * Transform a partition bound specification
   */
  PartitionBoundSpec *
  transformPartitionBound(ParseState *pstate, Relation parent,
  						PartitionBoundSpec *spec)
  {
  	PartitionBoundSpec *result_spec;
  	PartitionKey key = RelationGetPartitionKey(parent);
  	char		strategy = get_partition_strategy(key);
  	int			partnatts = get_partition_natts(key);
  	List	   *partexprs = get_partition_exprs(key);
  
  	/* Avoid scribbling on input */
  	result_spec = copyObject(spec);
  
  	if (spec->is_default)
  	{
  		/*
  		 * Hash partitioning does not support a default partition; there's no
  		 * use case for it (since the set of partitions to create is perfectly
  		 * defined), and if users do get into it accidentally, it's hard to
  		 * back out from it afterwards.
  		 */
  		if (strategy == PARTITION_STRATEGY_HASH)
  			ereport(ERROR,
  					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
  					 errmsg("a hash-partitioned table may not have a default partition")));
  
  		/*
  		 * In case of the default partition, parser had no way to identify the
  		 * partition strategy. Assign the parent's strategy to the default
  		 * partition bound spec.
  		 */
  		result_spec->strategy = strategy;
  
  		return result_spec;
  	}
  
  	if (strategy == PARTITION_STRATEGY_HASH)
  	{
  		if (spec->strategy != PARTITION_STRATEGY_HASH)
  			ereport(ERROR,
  					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
  					 errmsg("invalid bound specification for a hash partition"),
  					 parser_errposition(pstate, exprLocation((Node *) spec))));
  
  		if (spec->modulus <= 0)
  			ereport(ERROR,
  					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
  					 errmsg("modulus for hash partition must be a positive integer")));
  
  		Assert(spec->remainder >= 0);
  
  		if (spec->remainder >= spec->modulus)
  			ereport(ERROR,
  					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
  					 errmsg("remainder for hash partition must be less than modulus")));
  	}
  	else if (strategy == PARTITION_STRATEGY_LIST)
  	{
  		ListCell   *cell;
  		char	   *colname;
  		Oid			coltype;
  		int32		coltypmod;
  		Oid			partcollation;
  
  		if (spec->strategy != PARTITION_STRATEGY_LIST)
  			ereport(ERROR,
  					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
  					 errmsg("invalid bound specification for a list partition"),
  					 parser_errposition(pstate, exprLocation((Node *) spec))));
  
  		/* Get the only column's name in case we need to output an error */
  		if (key->partattrs[0] != 0)
  			colname = get_attname(RelationGetRelid(parent),
  								  key->partattrs[0], false);
  		else
  			colname = deparse_expression((Node *) linitial(partexprs),
  										 deparse_context_for(RelationGetRelationName(parent),
  															 RelationGetRelid(parent)),
  										 false, false);
  		/* Need its type data too */
  		coltype = get_partition_col_typid(key, 0);
  		coltypmod = get_partition_col_typmod(key, 0);
  		partcollation = get_partition_col_collation(key, 0);
  
  		result_spec->listdatums = NIL;
  		foreach(cell, spec->listdatums)
  		{
  			Node	   *expr = lfirst(cell);
  			Const	   *value;
  			ListCell   *cell2;
  			bool		duplicate;
  
  			value = transformPartitionBoundValue(pstate, expr,
  												 colname, coltype, coltypmod,
  												 partcollation);
  
  			/* Don't add to the result if the value is a duplicate */
  			duplicate = false;
  			foreach(cell2, result_spec->listdatums)
  			{
  				Const	   *value2 = castNode(Const, lfirst(cell2));
  
  				if (equal(value, value2))
  				{
  					duplicate = true;
  					break;
  				}
  			}
  			if (duplicate)
  				continue;
  
  			result_spec->listdatums = lappend(result_spec->listdatums,
  											  value);
  		}
  	}
  	else if (strategy == PARTITION_STRATEGY_RANGE)
  	{
  		if (spec->strategy != PARTITION_STRATEGY_RANGE)
  			ereport(ERROR,
  					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
  					 errmsg("invalid bound specification for a range partition"),
  					 parser_errposition(pstate, exprLocation((Node *) spec))));
  
  		if (list_length(spec->lowerdatums) != partnatts)
  			ereport(ERROR,
  					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
  					 errmsg("FROM must specify exactly one value per partitioning column")));
  		if (list_length(spec->upperdatums) != partnatts)
  			ereport(ERROR,
  					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
  					 errmsg("TO must specify exactly one value per partitioning column")));
  
  		/*
  		 * Convert raw parse nodes into PartitionRangeDatum nodes and perform
  		 * any necessary validation.
  		 */
  		result_spec->lowerdatums =
  			transformPartitionRangeBounds(pstate, spec->lowerdatums,
  										  parent);
  		result_spec->upperdatums =
  			transformPartitionRangeBounds(pstate, spec->upperdatums,
  										  parent);
  	}
  	else
  		elog(ERROR, "unexpected partition strategy: %d", (int) strategy);
  
  	return result_spec;
  }
  
  /*
   * transformPartitionRangeBounds
   *		This converts the expressions for range partition bounds from the raw
   *		grammar representation to PartitionRangeDatum structs
   */
  static List *
  transformPartitionRangeBounds(ParseState *pstate, List *blist,
  							  Relation parent)
  {
  	List	   *result = NIL;
  	PartitionKey key = RelationGetPartitionKey(parent);
  	List	   *partexprs = get_partition_exprs(key);
  	ListCell   *lc;
  	int			i,
  				j;
  
  	i = j = 0;
  	foreach(lc, blist)
  	{
  		Node	   *expr = lfirst(lc);
  		PartitionRangeDatum *prd = NULL;
  
  		/*
  		 * Infinite range bounds -- "minvalue" and "maxvalue" -- get passed in
  		 * as ColumnRefs.
  		 */
  		if (IsA(expr, ColumnRef))
  		{
  			ColumnRef  *cref = (ColumnRef *) expr;
  			char	   *cname = NULL;
  
  			/*
  			 * There should be a single field named either "minvalue" or
  			 * "maxvalue".
  			 */
  			if (list_length(cref->fields) == 1 &&
  				IsA(linitial(cref->fields), String))
  				cname = strVal(linitial(cref->fields));
  
  			if (cname == NULL)
  			{
  				/*
  				 * ColumnRef is not in the desired single-field-name form. For
  				 * consistency between all partition strategies, let the
  				 * expression transformation report any errors rather than
  				 * doing it ourselves.
  				 */
  			}
  			else if (strcmp("minvalue", cname) == 0)
  			{
  				prd = makeNode(PartitionRangeDatum);
  				prd->kind = PARTITION_RANGE_DATUM_MINVALUE;
  				prd->value = NULL;
  			}
  			else if (strcmp("maxvalue", cname) == 0)
  			{
  				prd = makeNode(PartitionRangeDatum);
  				prd->kind = PARTITION_RANGE_DATUM_MAXVALUE;
  				prd->value = NULL;
  			}
  		}
  
  		if (prd == NULL)
  		{
  			char	   *colname;
  			Oid			coltype;
  			int32		coltypmod;
  			Oid			partcollation;
  			Const	   *value;
  
  			/* Get the column's name in case we need to output an error */
  			if (key->partattrs[i] != 0)
  				colname = get_attname(RelationGetRelid(parent),
  									  key->partattrs[i], false);
  			else
  			{
  				colname = deparse_expression((Node *) list_nth(partexprs, j),
  											 deparse_context_for(RelationGetRelationName(parent),
  																 RelationGetRelid(parent)),
  											 false, false);
  				++j;
  			}
  
  			/* Need its type data too */
  			coltype = get_partition_col_typid(key, i);
  			coltypmod = get_partition_col_typmod(key, i);
  			partcollation = get_partition_col_collation(key, i);
  
  			value = transformPartitionBoundValue(pstate, expr,
  												 colname,
  												 coltype, coltypmod,
  												 partcollation);
  			if (value->constisnull)
  				ereport(ERROR,
  						(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
  						 errmsg("cannot specify NULL in range bound")));
  			prd = makeNode(PartitionRangeDatum);
  			prd->kind = PARTITION_RANGE_DATUM_VALUE;
  			prd->value = (Node *) value;
  			++i;
  		}
  
  		prd->location = exprLocation(expr);
  
  		result = lappend(result, prd);
  	}
  
  	/*
  	 * Once we see MINVALUE or MAXVALUE for one column, the remaining columns
  	 * must be the same.
  	 */
  	validateInfiniteBounds(pstate, result);
  
  	return result;
  }
  
  /*
   * validateInfiniteBounds
   *
   * Check that a MAXVALUE or MINVALUE specification in a partition bound is
   * followed only by more of the same.
   */
  static void
  validateInfiniteBounds(ParseState *pstate, List *blist)
  {
  	ListCell   *lc;
  	PartitionRangeDatumKind kind = PARTITION_RANGE_DATUM_VALUE;
  
  	foreach(lc, blist)
  	{
  		PartitionRangeDatum *prd = castNode(PartitionRangeDatum, lfirst(lc));
  
  		if (kind == prd->kind)
  			continue;
  
  		switch (kind)
  		{
  			case PARTITION_RANGE_DATUM_VALUE:
  				kind = prd->kind;
  				break;
  
  			case PARTITION_RANGE_DATUM_MAXVALUE:
  				ereport(ERROR,
  						(errcode(ERRCODE_DATATYPE_MISMATCH),
  						 errmsg("every bound following MAXVALUE must also be MAXVALUE"),
  						 parser_errposition(pstate, exprLocation((Node *) prd))));
  				break;
  
  			case PARTITION_RANGE_DATUM_MINVALUE:
  				ereport(ERROR,
  						(errcode(ERRCODE_DATATYPE_MISMATCH),
  						 errmsg("every bound following MINVALUE must also be MINVALUE"),
  						 parser_errposition(pstate, exprLocation((Node *) prd))));
  				break;
  		}
  	}
  }
  
  /*
   * Transform one constant in a partition bound spec
   */
  static Const *
  transformPartitionBoundValue(ParseState *pstate, Node *val,
  							 const char *colName, Oid colType, int32 colTypmod,
  							 Oid partCollation)
  {
  	Node	   *value;
  
  	/* Transform raw parsetree */
  	value = transformExpr(pstate, val, EXPR_KIND_PARTITION_BOUND);
  
  	/*
  	 * Check that the input expression's collation is compatible with one
  	 * specified for the parent's partition key (partcollation).  Don't throw
  	 * an error if it's the default collation which we'll replace with the
  	 * parent's collation anyway.
  	 */
  	if (IsA(value, CollateExpr))
  	{
  		Oid			exprCollOid = exprCollation(value);
  
  		if (OidIsValid(exprCollOid) &&
  			exprCollOid != DEFAULT_COLLATION_OID &&
  			exprCollOid != partCollation)
  			ereport(ERROR,
  					(errcode(ERRCODE_DATATYPE_MISMATCH),
  					 errmsg("collation of partition bound value for column \"%s\" does not match partition key collation \"%s\"",
  							colName, get_collation_name(partCollation)),
  					 parser_errposition(pstate, exprLocation(value))));
  	}
  
  	/* Coerce to correct type */
  	value = coerce_to_target_type(pstate,
  								  value, exprType(value),
  								  colType,
  								  colTypmod,
  								  COERCION_ASSIGNMENT,
  								  COERCE_IMPLICIT_CAST,
  								  -1);
  
  	if (value == NULL)
  		ereport(ERROR,
  				(errcode(ERRCODE_DATATYPE_MISMATCH),
  				 errmsg("specified value cannot be cast to type %s for column \"%s\"",
  						format_type_be(colType), colName),
  				 parser_errposition(pstate, exprLocation(val))));
  
  	/* Simplify the expression, in case we had a coercion */
  	if (!IsA(value, Const))
  		value = (Node *) expression_planner((Expr *) value);
  
  	/*
  	 * transformExpr() should have already rejected column references,
  	 * subqueries, aggregates, window functions, and SRFs, based on the
  	 * EXPR_KIND_ for a default expression.
  	 */
  	Assert(!contain_var_clause(value));
  
  	/*
  	 * Evaluate the expression, assigning the partition key's collation to the
  	 * resulting Const expression.
  	 */
  	value = (Node *) evaluate_expr((Expr *) value, colType, colTypmod,
  								   partCollation);
  	if (!IsA(value, Const))
  		elog(ERROR, "could not evaluate partition bound expression");
  
  	return (Const *) value;
  }
  