/*-------------------------------------------------------------------------
 *
 * 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) 1996-2008, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *	$PostgreSQL: pgsql/src/backend/parser/parse_utilcmd.c,v 2.14 2008/07/16 01:30:22 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include "access/genam.h"
#include "access/heapam.h"
#include "access/reloptions.h"
#include "catalog/dependency.h"
#include "catalog/heap.h"
#include "catalog/index.h"
#include "catalog/namespace.h"
#include "catalog/pg_opclass.h"
#include "catalog/pg_type.h"
#include "commands/defrem.h"
#include "commands/tablecmds.h"
#include "commands/tablespace.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "optimizer/clauses.h"
#include "parser/analyze.h"
#include "parser/gramparse.h"
#include "parser/parse_clause.h"
#include "parser/parse_expr.h"
#include "parser/parse_relation.h"
#include "parser/parse_type.h"
#include "parser/parse_utilcmd.h"
#include "rewrite/rewriteManip.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/relcache.h"
#include "utils/syscache.h"


/* State shared by transformCreateStmt and its subroutines */
typedef struct
{
	const char *stmtType;		/* "CREATE TABLE" or "ALTER TABLE" */
	RangeVar   *relation;		/* relation to create */
	Relation	rel;			/* opened/locked rel, if ALTER */
	List	   *inhRelations;	/* relations to inherit from */
	bool		isalter;		/* true if altering existing table */
	bool		hasoids;		/* does relation have an OID column? */
	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	   *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 */
} CreateStmtContext;

/* State shared by transformCreateSchemaStmt and its subroutines */
typedef struct
{
	const char *stmtType;		/* "CREATE SCHEMA" or "ALTER SCHEMA" */
	char	   *schemaname;		/* name of schema */
	char	   *authid;			/* 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(ParseState *pstate,
						  CreateStmtContext *cxt,
						  ColumnDef *column);
static void transformTableConstraint(ParseState *pstate,
						 CreateStmtContext *cxt,
						 Constraint *constraint);
static void transformInhRelation(ParseState *pstate, CreateStmtContext *cxt,
					 InhRelation *inhrelation);
static IndexStmt *generateClonedIndexStmt(CreateStmtContext *cxt,
						Relation parent_index, AttrNumber *attmap);
static List *get_opclass(Oid opclass, Oid actual_datatype);
static void transformIndexConstraints(ParseState *pstate,
						  CreateStmtContext *cxt);
static IndexStmt *transformIndexConstraint(Constraint *constraint,
						 CreateStmtContext *cxt);
static void transformFKConstraints(ParseState *pstate,
					   CreateStmtContext *cxt,
					   bool skipValidation,
					   bool isAddConstraint);
static void transformConstraintAttrs(List *constraintList);
static void transformColumnType(ParseState *pstate, ColumnDef *column);
static void setSchemaName(char *context_schema, char **stmt_schema_name);


/*
 * 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.
 *
 * SQL92 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;

	/*
	 * We must not scribble on the passed-in CreateStmt, so copy it.  (This is
	 * overkill, but easy.)
	 */
	stmt = (CreateStmt *) copyObject(stmt);

	/*
	 * 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.	"istemp" is equivalent to a
	 * specification of pg_temp, so no need for anything extra in that case.
	 */
	if (stmt->relation->schemaname == NULL && !stmt->relation->istemp)
	{
		Oid			namespaceid = RangeVarGetCreationNamespace(stmt->relation);

		stmt->relation->schemaname = get_namespace_name(namespaceid);
	}

	/* Set up pstate */
	pstate = make_parsestate(NULL);
	pstate->p_sourcetext = queryString;

	cxt.stmtType = "CREATE TABLE";
	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.blist = NIL;
	cxt.alist = NIL;
	cxt.pkey = NULL;
	cxt.hasoids = interpretOidsOption(stmt->options);

	/*
	 * 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(pstate, &cxt,
										  (ColumnDef *) element);
				break;

			case T_Constraint:
				transformTableConstraint(pstate, &cxt,
										 (Constraint *) element);
				break;

			case T_FkConstraint:
				/* No pre-transformation needed */
				cxt.fkconstraints = lappend(cxt.fkconstraints, element);
				break;

			case T_InhRelation:
				transformInhRelation(pstate, &cxt,
									 (InhRelation *) element);
				break;

			default:
				elog(ERROR, "unrecognized node type: %d",
					 (int) nodeTag(element));
				break;
		}
	}

	/*
	 * transformIndexConstraints wants cxt.alist to contain only index
	 * statements, so transfer anything we already have into save_alist.
	 */
	save_alist = cxt.alist;
	cxt.alist = NIL;

	Assert(stmt->constraints == NIL);

	/*
	 * Postprocess constraints that give rise to index definitions.
	 */
	transformIndexConstraints(pstate, &cxt);

	/*
	 * Postprocess foreign-key constraints.
	 */
	transformFKConstraints(pstate, &cxt, true, false);

	/*
	 * 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;
}

/*
 * transformColumnDefinition -
 *		transform a single ColumnDef within CREATE TABLE
 *		Also used in ALTER TABLE ADD COLUMN
 */
static void
transformColumnDefinition(ParseState *pstate, CreateStmtContext *cxt,
						  ColumnDef *column)
{
	bool		is_serial;
	bool		saw_nullable;
	bool		saw_default;
	Constraint *constraint;
	ListCell   *clist;

	cxt->columns = lappend(cxt->columns, column);

	/* Check for SERIAL pseudo-types */
	is_serial = false;
	if (list_length(column->typename->names) == 1 &&
		!column->typename->pct_type)
	{
		char	   *typname = strVal(linitial(column->typename->names));

		if (strcmp(typname, "serial") == 0 ||
			strcmp(typname, "serial4") == 0)
		{
			is_serial = true;
			column->typename->names = NIL;
			column->typename->typeid = INT4OID;
		}
		else if (strcmp(typname, "bigserial") == 0 ||
				 strcmp(typname, "serial8") == 0)
		{
			is_serial = true;
			column->typename->names = NIL;
			column->typename->typeid = 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")));
	}

	/* Do necessary work on the column type declaration */
	transformColumnType(pstate, column);

	/* Special actions for SERIAL pseudo-types */
	if (is_serial)
	{
		Oid			snamespaceid;
		char	   *snamespace;
		char	   *sname;
		char	   *qstring;
		A_Const    *snamenode;
		TypeCast   *castnode;
		FuncCall   *funccallnode;
		CreateSeqStmt *seqstmt;
		AlterSeqStmt *altseqstmt;
		List	   *attnamelist;

		/*
		 * Determine namespace and name to use for the sequence.
		 *
		 * 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.
		 */
		if (cxt->rel)
			snamespaceid = RelationGetNamespace(cxt->rel);
		else
			snamespaceid = RangeVarGetCreationNamespace(cxt->relation);
		snamespace = get_namespace_name(snamespaceid);
		sname = ChooseRelationName(cxt->relation->relname,
								   column->colname,
								   "seq",
								   snamespaceid);

		ereport(NOTICE,
				(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->sequence = makeRangeVar(snamespace, sname);
		seqstmt->options = NIL;

		cxt->blist = lappend(cxt->blist, seqstmt);

		/*
		 * 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);
		attnamelist = list_make3(makeString(snamespace),
								 makeString(cxt->relation->relname),
								 makeString(column->colname));
		altseqstmt->options = list_make1(makeDefElem("owned_by",
													 (Node *) attnamelist));

		cxt->alist = lappend(cxt->alist, altseqstmt);

		/*
		 * 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;
		castnode = makeNode(TypeCast);
		castnode->typename = SystemTypeName("regclass");
		castnode->arg = (Node *) snamenode;
		funccallnode = makeNode(FuncCall);
		funccallnode->funcname = SystemFuncName("nextval");
		funccallnode->args = list_make1(castnode);
		funccallnode->agg_star = false;
		funccallnode->agg_distinct = false;
		funccallnode->func_variadic = false;
		funccallnode->location = -1;

		constraint = makeNode(Constraint);
		constraint->contype = CONSTR_DEFAULT;
		constraint->raw_expr = (Node *) funccallnode;
		constraint->cooked_expr = NULL;
		constraint->keys = NIL;
		column->constraints = lappend(column->constraints, constraint);

		constraint = makeNode(Constraint);
		constraint->contype = CONSTR_NOTNULL;
		column->constraints = lappend(column->constraints, constraint);
	}

	/* Process column constraints, if any... */
	transformConstraintAttrs(column->constraints);

	saw_nullable = false;
	saw_default = false;

	foreach(clist, column->constraints)
	{
		constraint = lfirst(clist);

		/*
		 * If this column constraint is a FOREIGN KEY constraint, then we fill
		 * in the current attribute's name and throw it into the list of FK
		 * constraints to be processed later.
		 */
		if (IsA(constraint, FkConstraint))
		{
			FkConstraint *fkconstraint = (FkConstraint *) constraint;

			fkconstraint->fk_attrs = list_make1(makeString(column->colname));
			cxt->fkconstraints = lappend(cxt->fkconstraints, fkconstraint);
			continue;
		}

		Assert(IsA(constraint, Constraint));

		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)));
				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)));
				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)));
				column->raw_default = constraint->raw_expr;
				Assert(constraint->cooked_expr == NULL);
				saw_default = true;
				break;

			case CONSTR_PRIMARY:
			case CONSTR_UNIQUE:
				if (constraint->keys == NIL)
					constraint->keys = list_make1(makeString(column->colname));
				cxt->ixconstraints = lappend(cxt->ixconstraints, constraint);
				break;

			case CONSTR_CHECK:
				cxt->ckconstraints = lappend(cxt->ckconstraints, 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;
		}
	}
}

/*
 * transformTableConstraint
 *		transform a Constraint node within CREATE TABLE or ALTER TABLE
 */
static void
transformTableConstraint(ParseState *pstate, CreateStmtContext *cxt,
						 Constraint *constraint)
{
	switch (constraint->contype)
	{
		case CONSTR_PRIMARY:
		case CONSTR_UNIQUE:
			cxt->ixconstraints = lappend(cxt->ixconstraints, constraint);
			break;

		case CONSTR_CHECK:
			cxt->ckconstraints = lappend(cxt->ckconstraints, 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;
	}
}

/*
 * transformInhRelation
 *
 * Change the LIKE <subtable> portion of a CREATE TABLE statement into
 * column definitions which recreate the user defined column portions of
 * <subtable>.
 */
static void
transformInhRelation(ParseState *pstate, CreateStmtContext *cxt,
					 InhRelation *inhRelation)
{
	AttrNumber	parent_attno;
	Relation	relation;
	TupleDesc	tupleDesc;
	TupleConstr *constr;
	AclResult	aclresult;
	bool		including_defaults = false;
	bool		including_constraints = false;
	bool		including_indexes = false;
	ListCell   *elem;

	relation = heap_openrv(inhRelation->relation, AccessShareLock);

	if (relation->rd_rel->relkind != RELKIND_RELATION)
		ereport(ERROR,
				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
				 errmsg("inherited relation \"%s\" is not a table",
						inhRelation->relation->relname)));

	/*
	 * Check for SELECT privilages
	 */
	aclresult = pg_class_aclcheck(RelationGetRelid(relation), GetUserId(),
								  ACL_SELECT);
	if (aclresult != ACLCHECK_OK)
		aclcheck_error(aclresult, ACL_KIND_CLASS,
					   RelationGetRelationName(relation));

	tupleDesc = RelationGetDescr(relation);
	constr = tupleDesc->constr;

	foreach(elem, inhRelation->options)
	{
		int			option = lfirst_int(elem);

		switch (option)
		{
			case CREATE_TABLE_LIKE_INCLUDING_DEFAULTS:
				including_defaults = true;
				break;
			case CREATE_TABLE_LIKE_EXCLUDING_DEFAULTS:
				including_defaults = false;
				break;
			case CREATE_TABLE_LIKE_INCLUDING_CONSTRAINTS:
				including_constraints = true;
				break;
			case CREATE_TABLE_LIKE_EXCLUDING_CONSTRAINTS:
				including_constraints = false;
				break;
			case CREATE_TABLE_LIKE_INCLUDING_INDEXES:
				including_indexes = true;
				break;
			case CREATE_TABLE_LIKE_EXCLUDING_INDEXES:
				including_indexes = false;
				break;
			default:
				elog(ERROR, "unrecognized CREATE TABLE LIKE option: %d",
					 option);
		}
	}

	/*
	 * 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 = tupleDesc->attrs[parent_attno - 1];
		char	   *attributeName = NameStr(attribute->attname);
		ColumnDef  *def;

		/*
		 * Ignore dropped columns in the parent.
		 */
		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->raw_default = NULL;
		def->cooked_default = NULL;
		def->constraints = NIL;

		/*
		 * Add to column list
		 */
		cxt->columns = lappend(cxt->columns, def);

		/*
		 * Copy default, if present and the default has been requested
		 */
		if (attribute->atthasdef && including_defaults)
		{
			char	   *this_default = NULL;
			AttrDefault *attrdef;
			int			i;

			/* 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 = attrdef[i].adbin;
					break;
				}
			}
			Assert(this_default != NULL);

			/*
			 * If default expr could contain any vars, we'd need to fix 'em,
			 * but it can't; so default is ready to apply to child.
			 */

			def->cooked_default = pstrdup(this_default);
		}
	}

	/*
	 * Copy CHECK constraints if requested, being careful to adjust attribute
	 * numbers
	 */
	if (including_constraints && tupleDesc->constr)
	{
		AttrNumber *attmap = varattnos_map_schema(tupleDesc, cxt->columns);
		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;
			Node	   *ccbin_node = stringToNode(ccbin);
			Constraint *n = makeNode(Constraint);

			change_varattnos_of_a_node(ccbin_node, attmap);

			n->contype = CONSTR_CHECK;
			n->name = pstrdup(ccname);
			n->raw_expr = NULL;
			n->cooked_expr = nodeToString(ccbin_node);
			n->indexspace = NULL;
			cxt->ckconstraints = lappend(cxt->ckconstraints, (Node *) n);
		}
	}

	/*
	 * Likewise, copy indexes if requested
	 */
	if (including_indexes && relation->rd_rel->relhasindex)
	{
		AttrNumber *attmap = varattnos_map_schema(tupleDesc, cxt->columns);
		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, parent_index, attmap);

			/* 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);
		}
	}

	/*
	 * 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.
	 */
	heap_close(relation, NoLock);
}

/*
 * Generate an IndexStmt node using information from an already existing index
 * "source_idx".  Attribute numbers should be adjusted according to attmap.
 */
static IndexStmt *
generateClonedIndexStmt(CreateStmtContext *cxt, Relation source_idx,
						AttrNumber *attmap)
{
	Oid			source_relid = RelationGetRelid(source_idx);
	HeapTuple	ht_idxrel;
	HeapTuple	ht_idx;
	Form_pg_class idxrelrec;
	Form_pg_index idxrec;
	Form_pg_am	amrec;
	oidvector  *indclass;
	IndexStmt  *index;
	List	   *indexprs;
	ListCell   *indexpr_item;
	Oid			indrelid;
	int			keyno;
	Oid			keycoltype;
	Datum		datum;
	bool		isnull;

	/*
	 * 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 = SearchSysCache(RELOID,
							   ObjectIdGetDatum(source_relid),
							   0, 0, 0);
	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 pg_am tuple for source index from relcache entry */
	amrec = source_idx->rd_am;

	/* Must get indclass the hard way, since it's not stored in relcache */
	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 = cxt->relation;
	index->accessMethod = pstrdup(NameStr(amrec->amname));
	if (OidIsValid(idxrelrec->reltablespace))
		index->tableSpace = get_tablespace_name(idxrelrec->reltablespace);
	else
		index->tableSpace = NULL;
	index->unique = idxrec->indisunique;
	index->primary = idxrec->indisprimary;
	index->concurrent = false;

	/*
	 * We don't try to preserve the name of the source index; instead, just
	 * let DefineIndex() choose a reasonable name.
	 */
	index->idxname = NULL;

	/*
	 * If the index is marked PRIMARY, it's certainly from a constraint;
	 * else, if it's not marked UNIQUE, it certainly isn't; else, we have
	 * to search pg_depend to see if there's an associated unique constraint.
	 */
	if (index->primary)
		index->isconstraint = true;
	else if (!index->unique)
		index->isconstraint = false;
	else
		index->isconstraint = OidIsValid(get_index_constraint(source_relid));

	/* 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;

	indexpr_item = list_head(indexprs);
	for (keyno = 0; keyno < idxrec->indnatts; keyno++)
	{
		IndexElem  *iparam;
		AttrNumber	attnum = idxrec->indkey.values[keyno];
		int16		opt = source_idx->rd_indoption[keyno];

		iparam = makeNode(IndexElem);

		if (AttributeNumberIsValid(attnum))
		{
			/* Simple index column */
			char	   *attname;

			attname = get_relid_attribute_name(indrelid, attnum);
			keycoltype = get_atttype(indrelid, attnum);

			iparam->name = attname;
			iparam->expr = NULL;
		}
		else
		{
			/* Expressional index */
			Node	   *indexkey;

			if (indexpr_item == NULL)
				elog(ERROR, "too few entries in indexprs list");
			indexkey = (Node *) lfirst(indexpr_item);
			indexpr_item = lnext(indexpr_item);

			/* OK to modify indexkey since we are working on a private copy */
			change_varattnos_of_a_node(indexkey, attmap);

			iparam->name = NULL;
			iparam->expr = indexkey;

			keycoltype = exprType(indexkey);
		}

		/* 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 (amrec->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);
	}

	/* 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;

		/* Convert text string to node tree */
		pred_str = TextDatumGetCString(datum);
		index->whereClause = (Node *) stringToNode(pred_str);
		/* Adjust attribute numbers */
		change_varattnos_of_a_node(index->whereClause, attmap);
	}

	/* Clean up */
	ReleaseSysCache(ht_idxrel);

	return index;
}

/*
 * get_opclass			- fetch 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)
{
	HeapTuple	ht_opc;
	Form_pg_opclass opc_rec;
	List	   *result = NIL;

	ht_opc = SearchSysCache(CLAOID,
							ObjectIdGetDatum(opclass),
							0, 0, 0);
	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 and PRIMARY KEY constraints, which create indexes.
 *		We also merge in any index definitions arising from
 *		LIKE ... INCLUDING INDEXES.
 */
static void
transformIndexConstraints(ParseState *pstate, CreateStmtContext *cxt)
{
	IndexStmt  *index;
	List	   *indexlist = 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,
	 * create an index as for PRIMARY KEY, but do not insist on NOT NULL.
	 */
	foreach(lc, cxt->ixconstraints)
	{
		Constraint *constraint = (Constraint *) lfirst(lc);

		Assert(IsA(constraint, Constraint));
		Assert(constraint->contype == CONSTR_PRIMARY ||
			   constraint->contype == CONSTR_UNIQUE);

		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 SQL92 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.
	 */
	Assert(cxt->alist == NIL);
	if (cxt->pkey != NULL)
	{
		/* Make sure we keep the PKEY index in preference to others... */
		cxt->alist = list_make1(cxt->pkey);
	}

	foreach(lc, indexlist)
	{
		bool		keep = true;
		ListCell   *k;

		index = lfirst(lc);

		/* if it's pkey, it's already in cxt->alist */
		if (index == cxt->pkey)
			continue;

		foreach(k, cxt->alist)
		{
			IndexStmt  *priorindex = lfirst(k);

			if (equal(index->indexParams, priorindex->indexParams) &&
				equal(index->whereClause, priorindex->whereClause) &&
				strcmp(index->accessMethod, priorindex->accessMethod) == 0)
			{
				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)
			cxt->alist = lappend(cxt->alist, index);
	}
}

/*
 * transformIndexConstraint
 *		Transform one UNIQUE or PRIMARY KEY constraint for
 *		transformIndexConstraints.
 */
static IndexStmt *
transformIndexConstraint(Constraint *constraint, CreateStmtContext *cxt)
{
	IndexStmt  *index;
	ListCell   *keys;
	IndexElem  *iparam;

	index = makeNode(IndexStmt);

	index->unique = true;
	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)));
		cxt->pkey = index;

		/*
		 * In ALTER TABLE case, a primary index might already exist, but
		 * DefineIndex will check for it.
		 */
	}
	index->isconstraint = true;

	if (constraint->name != NULL)
		index->idxname = pstrdup(constraint->name);
	else
		index->idxname = NULL;	/* DefineIndex will choose name */

	index->relation = cxt->relation;
	index->accessMethod = DEFAULT_INDEX_TYPE;
	index->options = constraint->options;
	index->tableSpace = constraint->indexspace;
	index->indexParams = NIL;
	index->whereClause = NULL;
	index->concurrent = false;

	/*
	 * Make sure referenced keys exist.  If we are making a PRIMARY KEY index,
	 * also make sure they are NOT NULL, if possible. (Although we could leave
	 * it to DefineIndex to mark the columns NOT NULL, it's more efficient to
	 * get it right the first time.)
	 */
	foreach(keys, constraint->keys)
	{
		char	   *key = strVal(lfirst(keys));
		bool		found = false;
		ColumnDef  *column = NULL;
		ListCell   *columns;

		foreach(columns, cxt->columns)
		{
			column = (ColumnDef *) lfirst(columns);
			Assert(IsA(column, ColumnDef));
			if (strcmp(column->colname, key) == 0)
			{
				found = true;
				break;
			}
		}
		if (found)
		{
			/* found column in the new table; force it to be NOT NULL */
			if (constraint->contype == CONSTR_PRIMARY)
				column->is_not_null = TRUE;
		}
		else if (SystemAttributeByName(key, cxt->hasoids) != 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 = (RangeVar *) lfirst(inher);
				Relation	rel;
				int			count;

				Assert(IsA(inh, RangeVar));
				rel = heap_openrv(inh, AccessShareLock);
				if (rel->rd_rel->relkind != RELKIND_RELATION)
					ereport(ERROR,
							(errcode(ERRCODE_WRONG_OBJECT_TYPE),
						   errmsg("inherited relation \"%s\" is not a table",
								  inh->relname)));
				for (count = 0; count < rel->rd_att->natts; count++)
				{
					Form_pg_attribute inhattr = rel->rd_att->attrs[count];
					char	   *inhname = NameStr(inhattr->attname);

					if (inhattr->attisdropped)
						continue;
					if (strcmp(key, inhname) == 0)
					{
						found = true;

						/*
						 * We currently have no easy way to force an inherited
						 * column to be NOT NULL at creation, if its parent
						 * wasn't so already. We leave it to DefineIndex to
						 * fix things up in this case.
						 */
						break;
					}
				}
				heap_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, and will also take care of marking
		 * them NOT NULL.
		 */
		if (!found && !cxt->isalter)
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_COLUMN),
					 errmsg("column \"%s\" named in key does not exist",
							key)));

		/* 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)));
				else
					ereport(ERROR,
							(errcode(ERRCODE_DUPLICATE_COLUMN),
					errmsg("column \"%s\" appears twice in unique constraint",
						   key)));
			}
		}

		/* OK, add it to the index definition */
		iparam = makeNode(IndexElem);
		iparam->name = pstrdup(key);
		iparam->expr = NULL;
		iparam->opclass = NIL;
		iparam->ordering = SORTBY_DEFAULT;
		iparam->nulls_ordering = SORTBY_NULLS_DEFAULT;
		index->indexParams = lappend(index->indexParams, iparam);
	}

	return index;
}

/*
 * transformFKConstraints
 *		handle FOREIGN KEY constraints
 */
static void
transformFKConstraints(ParseState *pstate, 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 the constraint.
	 */
	if (skipValidation)
	{
		foreach(fkclist, cxt->fkconstraints)
		{
			FkConstraint *fkconstraint = (FkConstraint *) lfirst(fkclist);

			fkconstraint->skip_validation = 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)
		{
			FkConstraint *fkconstraint = (FkConstraint *) lfirst(fkclist);
			AlterTableCmd *altercmd = makeNode(AlterTableCmd);

			altercmd->subtype = AT_ProcessedConstraint;
			altercmd->name = NULL;
			altercmd->def = (Node *) fkconstraint;
			alterstmt->cmds = lappend(alterstmt->cmds, altercmd);
		}

		cxt->alist = lappend(cxt->alist, alterstmt);
	}
}

/*
 * transformIndexStmt - parse analysis for CREATE INDEX
 *
 * 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.
 */
IndexStmt *
transformIndexStmt(IndexStmt *stmt, const char *queryString)
{
	Relation	rel;
	ParseState *pstate;
	RangeTblEntry *rte;
	ListCell   *l;

	/*
	 * We must not scribble on the passed-in IndexStmt, so copy it.  (This is
	 * overkill, but easy.)
	 */
	stmt = (IndexStmt *) copyObject(stmt);

	/*
	 * Open the parent table with appropriate locking.	We must do this
	 * because addRangeTableEntry() would acquire only AccessShareLock,
	 * leaving DefineIndex() needing to do a lock upgrade with consequent risk
	 * of deadlock.  Make sure this stays in sync with the type of lock
	 * DefineIndex() wants.
	 */
	rel = heap_openrv(stmt->relation,
				  (stmt->concurrent ? ShareUpdateExclusiveLock : ShareLock));

	/* 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.
	 */
	rte = addRangeTableEntry(pstate, stmt->relation, 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,
												 "WHERE");

	/* take care of any index expressions */
	foreach(l, stmt->indexParams)
	{
		IndexElem  *ielem = (IndexElem *) lfirst(l);

		if (ielem->expr)
		{
			ielem->expr = transformExpr(pstate, ielem->expr);

			/*
			 * We check only that the result type is legitimate; this is for
			 * consistency with what transformWhereClause() checks for the
			 * predicate.  DefineIndex() will make more checks.
			 */
			if (expression_returns_set(ielem->expr))
				ereport(ERROR,
						(errcode(ERRCODE_DATATYPE_MISMATCH),
						 errmsg("index expression cannot return a set")));
		}
	}

	/*
	 * Check that only the base rel is mentioned.
	 */
	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, but keep the lock */
	heap_close(rel, NoLock);

	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 = heap_openrv(stmt->relation, AccessExclusiveLock);

	/* 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,
										   makeAlias("*OLD*", NIL),
										   false, false);
	newrte = addRangeTableEntryForRelation(pstate, rel,
										   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),
										"WHERE");

	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")));

	/* aggregates not allowed (but subselects are okay) */
	if (pstate->p_hasAggs)
		ereport(ERROR,
				(errcode(ERRCODE_GROUPING_ERROR),
		   errmsg("cannot use aggregate function in rule WHERE condition")));

	/*
	 * '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,
												   makeAlias("*OLD*", NIL),
												   false, false);
			newrte = addRangeTableEntryForRelation(sub_pstate, rel,
												   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;
			}

			/*
			 * 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 */
	heap_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.
 */
List *
transformAlterTableStmt(AlterTableStmt *stmt, const char *queryString)
{
	Relation	rel;
	ParseState *pstate;
	CreateStmtContext cxt;
	List	   *result;
	List	   *save_alist;
	ListCell   *lcmd,
			   *l;
	List	   *newcmds = NIL;
	bool		skipValidation = true;
	AlterTableCmd *newcmd;

	/*
	 * We must not scribble on the passed-in AlterTableStmt, so copy it. (This
	 * is overkill, but easy.)
	 */
	stmt = (AlterTableStmt *) copyObject(stmt);

	/*
	 * Acquire exclusive lock on the target relation, which will be held until
	 * end of transaction.	This ensures any decisions we make here based on
	 * the state of the relation will still be good at execution. We must get
	 * exclusive lock now because execution will; taking a lower grade lock
	 * now and trying to upgrade later risks deadlock.
	 */
	rel = relation_openrv(stmt->relation, AccessExclusiveLock);

	/* Set up pstate */
	pstate = make_parsestate(NULL);
	pstate->p_sourcetext = queryString;

	cxt.stmtType = "ALTER TABLE";
	cxt.relation = stmt->relation;
	cxt.rel = rel;
	cxt.inhRelations = NIL;
	cxt.isalter = true;
	cxt.hasoids = false;		/* need not be right */
	cxt.columns = NIL;
	cxt.ckconstraints = NIL;
	cxt.fkconstraints = NIL;
	cxt.ixconstraints = NIL;
	cxt.inh_indexes = NIL;
	cxt.blist = NIL;
	cxt.alist = NIL;
	cxt.pkey = NULL;

	/*
	 * The only subtypes that currently require parse transformation handling
	 * are ADD COLUMN and ADD CONSTRAINT.  These largely re-use code from
	 * CREATE TABLE.
	 */
	foreach(lcmd, stmt->cmds)
	{
		AlterTableCmd *cmd = (AlterTableCmd *) lfirst(lcmd);

		switch (cmd->subtype)
		{
			case AT_AddColumn:
				{
					ColumnDef  *def = (ColumnDef *) cmd->def;

					Assert(IsA(def, ColumnDef));
					transformColumnDefinition(pstate, &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(pstate, &cxt,
											 (Constraint *) cmd->def);
				else if (IsA(cmd->def, FkConstraint))
				{
					cxt.fkconstraints = lappend(cxt.fkconstraints, cmd->def);
					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;

			default:
				newcmds = lappend(newcmds, cmd);
				break;
		}
	}

	/*
	 * transformIndexConstraints wants cxt.alist to contain only index
	 * statements, so transfer anything we already have into save_alist
	 * immediately.
	 */
	save_alist = cxt.alist;
	cxt.alist = NIL;

	/* Postprocess index and FK constraints */
	transformIndexConstraints(pstate, &cxt);

	transformFKConstraints(pstate, &cxt, skipValidation, true);

	/*
	 * 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 subcommand has already been
	 * through transformIndexStmt.
	 */
	foreach(l, cxt.alist)
	{
		Node	   *idxstmt = (Node *) lfirst(l);

		Assert(IsA(idxstmt, IndexStmt));
		newcmd = makeNode(AlterTableCmd);
		newcmd->subtype = AT_AddIndex;
		newcmd->def = (Node *) transformIndexStmt((IndexStmt *) idxstmt,
												  queryString);
		newcmds = lappend(newcmds, newcmd);
	}
	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);
	}

	/* Close rel but keep lock */
	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 primary
 * constraints, but someday they ought to be supported for other constraints.
 */
static void
transformConstraintAttrs(List *constraintList)
{
	Node	   *lastprimarynode = NULL;
	bool		saw_deferrability = false;
	bool		saw_initially = false;
	ListCell   *clist;

	foreach(clist, constraintList)
	{
		Node	   *node = lfirst(clist);

		if (!IsA(node, Constraint))
		{
			lastprimarynode = node;
			/* reset flags for new primary node */
			saw_deferrability = false;
			saw_initially = false;
		}
		else
		{
			Constraint *con = (Constraint *) node;

			switch (con->contype)
			{
				case CONSTR_ATTR_DEFERRABLE:
					if (lastprimarynode == NULL ||
						!IsA(lastprimarynode, FkConstraint))
						ereport(ERROR,
								(errcode(ERRCODE_SYNTAX_ERROR),
								 errmsg("misplaced DEFERRABLE clause")));
					if (saw_deferrability)
						ereport(ERROR,
								(errcode(ERRCODE_SYNTAX_ERROR),
								 errmsg("multiple DEFERRABLE/NOT DEFERRABLE clauses not allowed")));
					saw_deferrability = true;
					((FkConstraint *) lastprimarynode)->deferrable = true;
					break;
				case CONSTR_ATTR_NOT_DEFERRABLE:
					if (lastprimarynode == NULL ||
						!IsA(lastprimarynode, FkConstraint))
						ereport(ERROR,
								(errcode(ERRCODE_SYNTAX_ERROR),
								 errmsg("misplaced NOT DEFERRABLE clause")));
					if (saw_deferrability)
						ereport(ERROR,
								(errcode(ERRCODE_SYNTAX_ERROR),
								 errmsg("multiple DEFERRABLE/NOT DEFERRABLE clauses not allowed")));
					saw_deferrability = true;
					((FkConstraint *) lastprimarynode)->deferrable = false;
					if (saw_initially &&
						((FkConstraint *) lastprimarynode)->initdeferred)
						ereport(ERROR,
								(errcode(ERRCODE_SYNTAX_ERROR),
								 errmsg("constraint declared INITIALLY DEFERRED must be DEFERRABLE")));
					break;
				case CONSTR_ATTR_DEFERRED:
					if (lastprimarynode == NULL ||
						!IsA(lastprimarynode, FkConstraint))
						ereport(ERROR,
								(errcode(ERRCODE_SYNTAX_ERROR),
							 errmsg("misplaced INITIALLY DEFERRED clause")));
					if (saw_initially)
						ereport(ERROR,
								(errcode(ERRCODE_SYNTAX_ERROR),
								 errmsg("multiple INITIALLY IMMEDIATE/DEFERRED clauses not allowed")));
					saw_initially = true;
					((FkConstraint *) lastprimarynode)->initdeferred = true;

					/*
					 * If only INITIALLY DEFERRED appears, assume DEFERRABLE
					 */
					if (!saw_deferrability)
						((FkConstraint *) lastprimarynode)->deferrable = true;
					else if (!((FkConstraint *) lastprimarynode)->deferrable)
						ereport(ERROR,
								(errcode(ERRCODE_SYNTAX_ERROR),
								 errmsg("constraint declared INITIALLY DEFERRED must be DEFERRABLE")));
					break;
				case CONSTR_ATTR_IMMEDIATE:
					if (lastprimarynode == NULL ||
						!IsA(lastprimarynode, FkConstraint))
						ereport(ERROR,
								(errcode(ERRCODE_SYNTAX_ERROR),
							errmsg("misplaced INITIALLY IMMEDIATE clause")));
					if (saw_initially)
						ereport(ERROR,
								(errcode(ERRCODE_SYNTAX_ERROR),
								 errmsg("multiple INITIALLY IMMEDIATE/DEFERRED clauses not allowed")));
					saw_initially = true;
					((FkConstraint *) lastprimarynode)->initdeferred = false;
					break;
				default:
					/* Otherwise it's not an attribute */
					lastprimarynode = node;
					/* reset flags for new primary node */
					saw_deferrability = false;
					saw_initially = false;
					break;
			}
		}
	}
}

/*
 * Special handling of type definition for a column
 */
static void
transformColumnType(ParseState *pstate, ColumnDef *column)
{
	/*
	 * All we really need to do here is verify that the type is valid.
	 */
	Type		ctype = typenameType(pstate, column->typename, NULL);

	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.
 *
 * SQL92 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.authid = stmt->authid;
	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)));
}
