istrat.c

关系型数据库 Postgresql 6.5.2

/*-------------------------------------------------------------------------
 *
 * istrat.c
 *	  index scan strategy manipulation code and index strategy manipulation
 *	  operator code.
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /usr/local/cvsroot/pgsql/src/backend/access/index/istrat.c,v 1.33.2.2 1999/08/02 05:56:39 scrappy Exp $
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include "access/heapam.h"
#include "access/istrat.h"
#include "catalog/catname.h"
#include "catalog/pg_amop.h"
#include "catalog/pg_amproc.h"
#include "catalog/pg_index.h"
#include "catalog/pg_operator.h"
#include "miscadmin.h"
#include "utils/syscache.h"

#ifdef USE_ASSERT_CHECKING
static bool StrategyEvaluationIsValid(StrategyEvaluation evaluation);
static bool StrategyExpressionIsValid(StrategyExpression expression,
						  StrategyNumber maxStrategy);
static ScanKey StrategyMapGetScanKeyEntry(StrategyMap map,
						   StrategyNumber strategyNumber);
static bool StrategyOperatorIsValid(StrategyOperator operator,
						StrategyNumber maxStrategy);
static bool StrategyTermIsValid(StrategyTerm term,
					StrategyNumber maxStrategy);

#endif


/* ----------------------------------------------------------------
 *				   misc strategy support routines
 * ----------------------------------------------------------------
 */

/*
 *		StrategyNumberIsValid
 *		StrategyNumberIsInBounds
 *		StrategyMapIsValid
 *		StrategyTransformMapIsValid
 *		IndexStrategyIsValid
 *
 *				... are now macros in istrat.h -cim 4/27/91
 */

/*
 * StrategyMapGetScanKeyEntry
 *		Returns a scan key entry of a index strategy mapping member.
 *
 * Note:
 *		Assumes that the index strategy mapping is valid.
 *		Assumes that the index strategy number is valid.
 *		Bounds checking should be done outside this routine.
 */
static ScanKey
StrategyMapGetScanKeyEntry(StrategyMap map,
						   StrategyNumber strategyNumber)
{
	Assert(StrategyMapIsValid(map));
	Assert(StrategyNumberIsValid(strategyNumber));
	return &map->entry[strategyNumber - 1];
}

/*
 * IndexStrategyGetStrategyMap
 *		Returns an index strategy mapping of an index strategy.
 *
 * Note:
 *		Assumes that the index strategy is valid.
 *		Assumes that the number of index strategies is valid.
 *		Bounds checking should be done outside this routine.
 */
StrategyMap
IndexStrategyGetStrategyMap(IndexStrategy indexStrategy,
							StrategyNumber maxStrategyNum,
							AttrNumber attrNum)
{
	Assert(IndexStrategyIsValid(indexStrategy));
	Assert(StrategyNumberIsValid(maxStrategyNum));
	Assert(AttributeNumberIsValid(attrNum));

	maxStrategyNum = AMStrategies(maxStrategyNum);		/* XXX */
	return &indexStrategy->strategyMapData[maxStrategyNum * (attrNum - 1)];
}

/*
 * AttributeNumberGetIndexStrategySize
 *		Computes the size of an index strategy.
 */
Size
AttributeNumberGetIndexStrategySize(AttrNumber maxAttributeNumber,
									StrategyNumber maxStrategyNumber)
{
	maxStrategyNumber = AMStrategies(maxStrategyNumber);		/* XXX */
	return maxAttributeNumber * maxStrategyNumber * sizeof(ScanKeyData);
}

#ifdef USE_ASSERT_CHECKING
/*
 * StrategyTransformMapIsValid is now a macro in istrat.h -cim 4/27/91
 */

/* ----------------
 *		StrategyOperatorIsValid
 * ----------------
 */
static bool
StrategyOperatorIsValid(StrategyOperator operator,
						StrategyNumber maxStrategy)
{
	return (bool)
	(PointerIsValid(operator) &&
	 StrategyNumberIsInBounds(operator->strategy, maxStrategy) &&
	 !(operator->flags & ~(SK_NEGATE | SK_COMMUTE)));
}

/* ----------------
 *		StrategyTermIsValid
 * ----------------
 */
static bool
StrategyTermIsValid(StrategyTerm term,
					StrategyNumber maxStrategy)
{
	Index		index;

	if (!PointerIsValid(term) || term->degree == 0)
		return false;

	for (index = 0; index < term->degree; index += 1)
	{
		if (!StrategyOperatorIsValid(&term->operatorData[index],
									 maxStrategy))
			return false;
	}

	return true;
}

/* ----------------
 *		StrategyExpressionIsValid
 * ----------------
 */
static bool
StrategyExpressionIsValid(StrategyExpression expression,
						  StrategyNumber maxStrategy)
{
	StrategyTerm *termP;

	if (!PointerIsValid(expression))
		return true;

	if (!StrategyTermIsValid(expression->term[0], maxStrategy))
		return false;

	termP = &expression->term[1];
	while (StrategyTermIsValid(*termP, maxStrategy))
		termP += 1;

	return (bool)
		(!PointerIsValid(*termP));
}

/* ----------------
 *		StrategyEvaluationIsValid
 * ----------------
 */
static bool
StrategyEvaluationIsValid(StrategyEvaluation evaluation)
{
	Index		index;

	if (!PointerIsValid(evaluation) ||
		!StrategyNumberIsValid(evaluation->maxStrategy) ||
		!StrategyTransformMapIsValid(evaluation->negateTransform) ||
		!StrategyTransformMapIsValid(evaluation->commuteTransform) ||
		!StrategyTransformMapIsValid(evaluation->negateCommuteTransform))
	{

		return false;
	}

	for (index = 0; index < evaluation->maxStrategy; index += 1)
	{
		if (!StrategyExpressionIsValid(evaluation->expression[index],
									   evaluation->maxStrategy))
		{

			return false;
		}
	}
	return true;
}

#endif

/* ----------------
 *		StrategyTermEvaluate
 * ----------------
 */
static bool
StrategyTermEvaluate(StrategyTerm term,
					 StrategyMap map,
					 Datum left,
					 Datum right)
{
	Index		index;
	long		tmpres = 0;
	bool		result = 0;
	StrategyOperator operator;
	ScanKey		entry;

	for (index = 0, operator = &term->operatorData[0];
		 index < term->degree; index += 1, operator += 1)
	{

		entry = &map->entry[operator->strategy - 1];

		Assert(RegProcedureIsValid(entry->sk_procedure));

		switch (operator->flags ^ entry->sk_flags)
		{
			case 0x0:
				tmpres = (long) FMGR_PTR2(&entry->sk_func,
										  left, right);
				break;

			case SK_NEGATE:
				tmpres = (long) !FMGR_PTR2(&entry->sk_func,
										   left, right);
				break;

			case SK_COMMUTE:
				tmpres = (long) FMGR_PTR2(&entry->sk_func,
										  right, left);
				break;

			case SK_NEGATE | SK_COMMUTE:
				tmpres = (long) !FMGR_PTR2(&entry->sk_func,
										   right, left);
				break;

			default:
				elog(FATAL, "StrategyTermEvaluate: impossible case %d",
					 operator->flags ^ entry->sk_flags);
		}

		result = (bool) tmpres;
		if (!result)
			return result;
	}

	return result;
}


/* ----------------
 *		RelationGetStrategy
 * ----------------
 */
StrategyNumber
RelationGetStrategy(Relation relation,
					AttrNumber attributeNumber,
					StrategyEvaluation evaluation,
					RegProcedure procedure)
{
	StrategyNumber strategy;
	StrategyMap strategyMap;
	ScanKey		entry;
	Index		index;
	int			numattrs;

	Assert(RelationIsValid(relation));
	numattrs = RelationGetNumberOfAttributes(relation);

	Assert(relation->rd_rel->relkind == RELKIND_INDEX); /* XXX use accessor */
	Assert(AttributeNumberIsValid(attributeNumber));
	Assert((attributeNumber >= 1) && (attributeNumber < 1 + numattrs));

	Assert(StrategyEvaluationIsValid(evaluation));
	Assert(RegProcedureIsValid(procedure));

	strategyMap = IndexStrategyGetStrategyMap(RelationGetIndexStrategy(relation),
											  evaluation->maxStrategy,
											  attributeNumber);

	/* get a strategy number for the procedure ignoring flags for now */
	for (index = 0; index < evaluation->maxStrategy; index += 1)
	{
		if (strategyMap->entry[index].sk_procedure == procedure)
			break;
	}

	if (index == evaluation->maxStrategy)
		return InvalidStrategy;

	strategy = 1 + index;
	entry = StrategyMapGetScanKeyEntry(strategyMap, strategy);

	Assert(!(entry->sk_flags & ~(SK_NEGATE | SK_COMMUTE)));

	switch (entry->sk_flags & (SK_NEGATE | SK_COMMUTE))
	{
		case 0x0:
			return strategy;

		case SK_NEGATE:
			strategy = evaluation->negateTransform->strategy[strategy - 1];
			break;

		case SK_COMMUTE:
			strategy = evaluation->commuteTransform->strategy[strategy - 1];
			break;

		case SK_NEGATE | SK_COMMUTE:
			strategy = evaluation->negateCommuteTransform->strategy[strategy - 1];
			break;

		default:
			elog(FATAL, "RelationGetStrategy: impossible case %d", entry->sk_flags);
	}


	if (!StrategyNumberIsInBounds(strategy, evaluation->maxStrategy))
	{
		if (!StrategyNumberIsValid(strategy))
			elog(ERROR, "RelationGetStrategy: corrupted evaluation");
	}

	return strategy;
}

/* ----------------
 *		RelationInvokeStrategy
 * ----------------
 */
bool							/* XXX someday, this may return Datum */
RelationInvokeStrategy(Relation relation,
					   StrategyEvaluation evaluation,
					   AttrNumber attributeNumber,
					   StrategyNumber strategy,
					   Datum left,
					   Datum right)
{
	StrategyNumber newStrategy;
	StrategyMap strategyMap;
	ScanKey		entry;
	StrategyTermData termData;
	int			numattrs;