indexcmds.c

来自「PostgreSQL7.4.6 for Linux」· C语言 代码 · 共 777 行 · 第 1/2 页

/*-------------------------------------------------------------------------
 *
 * indexcmds.c
 *	  POSTGRES define and remove index code.
 *
 * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /cvsroot/pgsql/src/backend/commands/indexcmds.c,v 1.114 2003/10/02 06:34:03 petere Exp $
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include "access/heapam.h"
#include "catalog/catalog.h"
#include "catalog/catname.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_proc.h"
#include "commands/dbcommands.h"
#include "commands/defrem.h"
#include "commands/tablecmds.h"
#include "executor/executor.h"
#include "miscadmin.h"
#include "optimizer/clauses.h"
#include "optimizer/prep.h"
#include "parser/parsetree.h"
#include "parser/parse_coerce.h"
#include "parser/parse_expr.h"
#include "parser/parse_func.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/syscache.h"


/* non-export function prototypes */
static void CheckPredicate(List *predList);
static void ComputeIndexAttrs(IndexInfo *indexInfo, Oid *classOidP,
				  List *attList,
				  Oid relId,
				  char *accessMethodName, Oid accessMethodId);
static Oid GetIndexOpClass(List *opclass, Oid attrType,
				char *accessMethodName, Oid accessMethodId);
static Oid	GetDefaultOpClass(Oid attrType, Oid accessMethodId);

/*
 * DefineIndex
 *		Creates a new index.
 *
 * 'attributeList' is a list of IndexElem specifying columns and expressions
 *		to index on.
 * 'predicate' is the qual specified in the where clause.
 * 'rangetable' is needed to interpret the predicate.
 */
void
DefineIndex(RangeVar *heapRelation,
			char *indexRelationName,
			char *accessMethodName,
			List *attributeList,
			bool unique,
			bool primary,
			bool isconstraint,
			Expr *predicate,
			List *rangetable)
{
	Oid		   *classObjectId;
	Oid			accessMethodId;
	Oid			relationId;
	Oid			namespaceId;
	Relation	rel;
	HeapTuple	tuple;
	Form_pg_am	accessMethodForm;
	IndexInfo  *indexInfo;
	int			numberOfAttributes;
	List	   *cnfPred = NIL;

	/*
	 * count attributes in index
	 */
	numberOfAttributes = length(attributeList);
	if (numberOfAttributes <= 0)
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
				 errmsg("must specify at least one column")));
	if (numberOfAttributes > INDEX_MAX_KEYS)
		ereport(ERROR,
				(errcode(ERRCODE_TOO_MANY_COLUMNS),
				 errmsg("cannot use more than %d columns in an index",
						INDEX_MAX_KEYS)));

	/*
	 * Open heap relation, acquire a suitable lock on it, remember its OID
	 */
	rel = heap_openrv(heapRelation, ShareLock);

	/* Note: during bootstrap may see uncataloged relation */
	if (rel->rd_rel->relkind != RELKIND_RELATION &&
		rel->rd_rel->relkind != RELKIND_UNCATALOGED)
		ereport(ERROR,
				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
				 errmsg("\"%s\" is not a table",
						heapRelation->relname)));

	relationId = RelationGetRelid(rel);
	namespaceId = RelationGetNamespace(rel);

	heap_close(rel, NoLock);

	/*
	 * Verify we (still) have CREATE rights in the rel's namespace.
	 * (Presumably we did when the rel was created, but maybe not
	 * anymore.) Skip check if bootstrapping, since permissions machinery
	 * may not be working yet.
	 */
	if (!IsBootstrapProcessingMode())
	{
		AclResult	aclresult;

		aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(),
										  ACL_CREATE);
		if (aclresult != ACLCHECK_OK)
			aclcheck_error(aclresult, ACL_KIND_NAMESPACE,
						   get_namespace_name(namespaceId));
	}

	/*
	 * look up the access method, verify it can handle the requested
	 * features
	 */
	tuple = SearchSysCache(AMNAME,
						   PointerGetDatum(accessMethodName),
						   0, 0, 0);
	if (!HeapTupleIsValid(tuple))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("access method \"%s\" does not exist",
						accessMethodName)));
	accessMethodId = HeapTupleGetOid(tuple);
	accessMethodForm = (Form_pg_am) GETSTRUCT(tuple);

	if (unique && !accessMethodForm->amcanunique)
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
		   errmsg("access method \"%s\" does not support unique indexes",
				  accessMethodName)));
	if (numberOfAttributes > 1 && !accessMethodForm->amcanmulticol)
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("access method \"%s\" does not support multicolumn indexes",
						accessMethodName)));

	ReleaseSysCache(tuple);

	/*
	 * If a range table was created then check that only the base rel is
	 * mentioned.
	 */
	if (rangetable != NIL)
	{
		if (length(rangetable) != 1 || getrelid(1, rangetable) != relationId)
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
					 errmsg("index expressions and predicates may refer only to the table being indexed")));
	}

	/*
	 * Convert the partial-index predicate from parsetree form to an
	 * implicit-AND qual expression, for easier evaluation at runtime.
	 * While we are at it, we reduce it to a canonical (CNF or DNF) form
	 * to simplify the task of proving implications.
	 */
	if (predicate)
	{
		cnfPred = canonicalize_qual((Expr *) copyObject(predicate), true);
		CheckPredicate(cnfPred);
	}

	/*
	 * Check that all of the attributes in a primary key are marked as not
	 * null, otherwise attempt to ALTER TABLE .. SET NOT NULL
	 */
	if (primary)
	{
		List	   *keys;

		foreach(keys, attributeList)
		{
			IndexElem  *key = (IndexElem *) lfirst(keys);
			HeapTuple	atttuple;

			if (!key->name)
				ereport(ERROR,
						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
						 errmsg("primary keys cannot be expressions")));

			/* System attributes are never null, so no problem */
			if (SystemAttributeByName(key->name, rel->rd_rel->relhasoids))
				continue;

			atttuple = SearchSysCacheAttName(relationId, key->name);
			if (HeapTupleIsValid(atttuple))
			{
				if (!((Form_pg_attribute) GETSTRUCT(atttuple))->attnotnull)
				{
					/*
					 * Try to make it NOT NULL.
					 *
					 * XXX: Shouldn't the ALTER TABLE .. SET NOT NULL cascade
					 * to child tables?  Currently, since the PRIMARY KEY
					 * itself doesn't cascade, we don't cascade the
					 * notnull constraint either; but this is pretty
					 * debatable.
					 */
					AlterTableAlterColumnSetNotNull(relationId, false,
													key->name);
				}
				ReleaseSysCache(atttuple);
			}
			else
			{
				/* This shouldn't happen if parser did its job ... */
				ereport(ERROR,
						(errcode(ERRCODE_UNDEFINED_COLUMN),
					  errmsg("column \"%s\" named in key does not exist",
							 key->name)));
			}
		}
	}

	/*
	 * Prepare arguments for index_create, primarily an IndexInfo
	 * structure
	 */
	indexInfo = makeNode(IndexInfo);
	indexInfo->ii_NumIndexAttrs = numberOfAttributes;
	indexInfo->ii_Expressions = NIL;	/* for now */
	indexInfo->ii_ExpressionsState = NIL;
	indexInfo->ii_Predicate = cnfPred;
	indexInfo->ii_PredicateState = NIL;
	indexInfo->ii_Unique = unique;

	classObjectId = (Oid *) palloc(numberOfAttributes * sizeof(Oid));
	ComputeIndexAttrs(indexInfo, classObjectId, attributeList,
					  relationId, accessMethodName, accessMethodId);

	index_create(relationId, indexRelationName,
				 indexInfo, accessMethodId, classObjectId,
				 primary, isconstraint, allowSystemTableMods);

	/*
	 * We update the relation's pg_class tuple even if it already has
	 * relhasindex = true.	This is needed to cause a shared-cache-inval
	 * message to be sent for the pg_class tuple, which will cause other
	 * backends to flush their relcache entries and in particular their
	 * cached lists of the indexes for this relation.
	 */
	setRelhasindex(relationId, true, primary, InvalidOid);
}


/*
 * CheckPredicate
 *		Checks that the given list of partial-index predicates is valid.
 *
 * This used to also constrain the form of the predicate to forms that
 * indxpath.c could do something with.	However, that seems overly
 * restrictive.  One useful application of partial indexes is to apply
 * a UNIQUE constraint across a subset of a table, and in that scenario
 * any evaluatable predicate will work.  So accept any predicate here
 * (except ones requiring a plan), and let indxpath.c fend for itself.
 */
static void
CheckPredicate(List *predList)
{
	/*
	 * We don't currently support generation of an actual query plan for a
	 * predicate, only simple scalar expressions; hence these
	 * restrictions.
	 */
	if (contain_subplans((Node *) predList))
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("cannot use subquery in index predicate")));
	if (contain_agg_clause((Node *) predList))
		ereport(ERROR,
				(errcode(ERRCODE_GROUPING_ERROR),
				 errmsg("cannot use aggregate in index predicate")));

	/*
	 * A predicate using mutable functions is probably wrong, for the same
	 * reasons that we don't allow an index expression to use one.
	 */
	if (contain_mutable_functions((Node *) predList))
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
		errmsg("functions in index predicate must be marked IMMUTABLE")));
}

static void
ComputeIndexAttrs(IndexInfo *indexInfo,
				  Oid *classOidP,
				  List *attList,	/* list of IndexElem's */
				  Oid relId,
				  char *accessMethodName,
				  Oid accessMethodId)
{
	List	   *rest;
	int			attn = 0;

	/*
	 * process attributeList
	 */
	foreach(rest, attList)
	{
		IndexElem  *attribute = (IndexElem *) lfirst(rest);
		Oid			atttype;

		if (attribute->name != NULL)
		{
			/* Simple index attribute */
			HeapTuple	atttuple;
			Form_pg_attribute attform;

			Assert(attribute->expr == NULL);
			atttuple = SearchSysCacheAttName(relId, attribute->name);
			if (!HeapTupleIsValid(atttuple))
				ereport(ERROR,
						(errcode(ERRCODE_UNDEFINED_COLUMN),
						 errmsg("column \"%s\" does not exist",
								attribute->name)));
			attform = (Form_pg_attribute) GETSTRUCT(atttuple);
			indexInfo->ii_KeyAttrNumbers[attn] = attform->attnum;
			atttype = attform->atttypid;
			ReleaseSysCache(atttuple);
		}
		else if (attribute->expr && IsA(attribute->expr, Var))
		{
			/* Tricky tricky, he wrote (column) ... treat as simple attr */
			Var		   *var = (Var *) attribute->expr;

			indexInfo->ii_KeyAttrNumbers[attn] = var->varattno;
			atttype = get_atttype(relId, var->varattno);
		}
		else
		{
			/* Index expression */
			Assert(attribute->expr != NULL);
			indexInfo->ii_KeyAttrNumbers[attn] = 0;		/* marks expression */
			indexInfo->ii_Expressions = lappend(indexInfo->ii_Expressions,
												attribute->expr);
			atttype = exprType(attribute->expr);

			/*
			 * We don't currently support generation of an actual query
			 * plan for an index expression, only simple scalar
			 * expressions; hence these restrictions.
			 */
			if (contain_subplans(attribute->expr))
				ereport(ERROR,
						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				   errmsg("cannot use subquery in index expression")));
			if (contain_agg_clause(attribute->expr))
				ereport(ERROR,
						(errcode(ERRCODE_GROUPING_ERROR),
					errmsg("cannot use aggregate function in index expression")));

			/*
			 * A expression using mutable functions is probably wrong,
			 * since if you aren't going to get the same result for the
			 * same data every time, it's not clear what the index entries
			 * mean at all.
			 */
			if (contain_mutable_functions(attribute->expr))
				ereport(ERROR,
						(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
						 errmsg("functions in index expression must be marked IMMUTABLE")));
		}

		classOidP[attn] = GetIndexOpClass(attribute->opclass,
										  atttype,
										  accessMethodName,