index.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

 */
Oid
index_create(Oid heapRelationId,
			 const char *indexRelationName,
			 Oid indexRelationId,
			 IndexInfo *indexInfo,
			 Oid accessMethodObjectId,
			 Oid tableSpaceId,
			 Oid *classObjectId,
			 bool primary,
			 bool isconstraint,
			 bool allow_system_table_mods,
			 bool skip_build)
{
	Relation	pg_class;
	Relation	heapRelation;
	Relation	indexRelation;
	TupleDesc	indexTupDesc;
	bool		shared_relation;
	Oid			namespaceId;
	int			i;

	pg_class = heap_open(RelationRelationId, RowExclusiveLock);

	/*
	 * Only SELECT ... FOR UPDATE/SHARE are allowed while doing this
	 */
	heapRelation = heap_open(heapRelationId, ShareLock);

	/*
	 * The index will be in the same namespace as its parent table, and is
	 * shared across databases if and only if the parent is.
	 */
	namespaceId = RelationGetNamespace(heapRelation);
	shared_relation = heapRelation->rd_rel->relisshared;

	/*
	 * check parameters
	 */
	if (indexInfo->ii_NumIndexAttrs < 1)
		elog(ERROR, "must index at least one column");

	if (!allow_system_table_mods &&
		IsSystemRelation(heapRelation) &&
		IsNormalProcessingMode())
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("user-defined indexes on system catalog tables are not supported")));

	/*
	 * We cannot allow indexing a shared relation after initdb (because
	 * there's no way to make the entry in other databases' pg_class).
	 * Unfortunately we can't distinguish initdb from a manually started
	 * standalone backend (toasting of shared rels happens after the bootstrap
	 * phase, so checking IsBootstrapProcessingMode() won't work).  However,
	 * we can at least prevent this mistake under normal multi-user operation.
	 */
	if (shared_relation && IsUnderPostmaster)
		ereport(ERROR,
				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
				 errmsg("shared indexes cannot be created after initdb")));

	if (get_relname_relid(indexRelationName, namespaceId))
		ereport(ERROR,
				(errcode(ERRCODE_DUPLICATE_TABLE),
				 errmsg("relation \"%s\" already exists",
						indexRelationName)));

	/*
	 * construct tuple descriptor for index tuples
	 */
	indexTupDesc = ConstructTupleDescriptor(heapRelation,
											indexInfo,
											classObjectId);

	/*
	 * Allocate an OID for the index, unless we were told what to use.
	 *
	 * The OID will be the relfilenode as well, so make sure it doesn't
	 * collide with either pg_class OIDs or existing physical files.
	 */
	if (!OidIsValid(indexRelationId))
		indexRelationId = GetNewRelFileNode(tableSpaceId, shared_relation,
											pg_class);

	/*
	 * create the index relation's relcache entry and physical disk file. (If
	 * we fail further down, it's the smgr's responsibility to remove the disk
	 * file again.)
	 */
	indexRelation = heap_create(indexRelationName,
								namespaceId,
								tableSpaceId,
								indexRelationId,
								indexTupDesc,
								RELKIND_INDEX,
								shared_relation,
								allow_system_table_mods);

	Assert(indexRelationId == RelationGetRelid(indexRelation));

	/*
	 * Obtain exclusive lock on it.  Although no other backends can see it
	 * until we commit, this prevents deadlock-risk complaints from lock
	 * manager in cases such as CLUSTER.
	 */
	LockRelation(indexRelation, AccessExclusiveLock);

	/*
	 * Fill in fields of the index's pg_class entry that are not set correctly
	 * by heap_create.
	 *
	 * XXX should have a cleaner way to create cataloged indexes
	 */
	indexRelation->rd_rel->relowner = heapRelation->rd_rel->relowner;
	indexRelation->rd_rel->relam = accessMethodObjectId;
	indexRelation->rd_rel->relkind = RELKIND_INDEX;
	indexRelation->rd_rel->relhasoids = false;

	/*
	 * store index's pg_class entry
	 */
	UpdateRelationRelation(pg_class, indexRelation);

	/* done with pg_class */
	heap_close(pg_class, RowExclusiveLock);

	/*
	 * now update the object id's of all the attribute tuple forms in the
	 * index relation's tuple descriptor
	 */
	InitializeAttributeOids(indexRelation,
							indexInfo->ii_NumIndexAttrs,
							indexRelationId);

	/*
	 * append ATTRIBUTE tuples for the index
	 */
	AppendAttributeTuples(indexRelation, indexInfo->ii_NumIndexAttrs);

	/* ----------------
	 *	  update pg_index
	 *	  (append INDEX tuple)
	 *
	 *	  Note that this stows away a representation of "predicate".
	 *	  (Or, could define a rule to maintain the predicate) --Nels, Feb '92
	 * ----------------
	 */
	UpdateIndexRelation(indexRelationId, heapRelationId, indexInfo,
						classObjectId, primary);

	/*
	 * Register constraint and dependencies for the index.
	 *
	 * If the index is from a CONSTRAINT clause, construct a pg_constraint
	 * entry. The index is then linked to the constraint, which in turn is
	 * linked to the table.  If it's not a CONSTRAINT, make the dependency
	 * directly on the table.
	 *
	 * We don't need a dependency on the namespace, because there'll be an
	 * indirect dependency via our parent table.
	 *
	 * During bootstrap we can't register any dependencies, and we don't try
	 * to make a constraint either.
	 */
	if (!IsBootstrapProcessingMode())
	{
		ObjectAddress myself,
					referenced;

		myself.classId = RelationRelationId;
		myself.objectId = indexRelationId;
		myself.objectSubId = 0;

		if (isconstraint)
		{
			char		constraintType;
			Oid			conOid;

			if (primary)
				constraintType = CONSTRAINT_PRIMARY;
			else if (indexInfo->ii_Unique)
				constraintType = CONSTRAINT_UNIQUE;
			else
			{
				elog(ERROR, "constraint must be PRIMARY or UNIQUE");
				constraintType = 0;		/* keep compiler quiet */
			}

			/* Shouldn't have any expressions */
			if (indexInfo->ii_Expressions)
				elog(ERROR, "constraints can't have index expressions");

			conOid = CreateConstraintEntry(indexRelationName,
										   namespaceId,
										   constraintType,
										   false,		/* isDeferrable */
										   false,		/* isDeferred */
										   heapRelationId,
										   indexInfo->ii_KeyAttrNumbers,
										   indexInfo->ii_NumIndexAttrs,
										   InvalidOid,	/* no domain */
										   InvalidOid,	/* no foreign key */
										   NULL,
										   0,
										   ' ',
										   ' ',
										   ' ',
										   InvalidOid,	/* no associated index */
										   NULL,		/* no check constraint */
										   NULL,
										   NULL);

			referenced.classId = ConstraintRelationId;
			referenced.objectId = conOid;
			referenced.objectSubId = 0;

			recordDependencyOn(&myself, &referenced, DEPENDENCY_INTERNAL);
		}
		else
		{
			/* Create auto dependencies on simply-referenced columns */
			for (i = 0; i < indexInfo->ii_NumIndexAttrs; i++)
			{
				if (indexInfo->ii_KeyAttrNumbers[i] != 0)
				{
					referenced.classId = RelationRelationId;
					referenced.objectId = heapRelationId;
					referenced.objectSubId = indexInfo->ii_KeyAttrNumbers[i];

					recordDependencyOn(&myself, &referenced, DEPENDENCY_AUTO);
				}
			}
		}

		/* Store dependency on operator classes */
		for (i = 0; i < indexInfo->ii_NumIndexAttrs; i++)
		{
			referenced.classId = OperatorClassRelationId;
			referenced.objectId = classObjectId[i];
			referenced.objectSubId = 0;

			recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
		}

		/* Store dependencies on anything mentioned in index expressions */
		if (indexInfo->ii_Expressions)
		{
			recordDependencyOnSingleRelExpr(&myself,
										  (Node *) indexInfo->ii_Expressions,
											heapRelationId,
											DEPENDENCY_NORMAL,
											DEPENDENCY_AUTO);
		}

		/* Store dependencies on anything mentioned in predicate */
		if (indexInfo->ii_Predicate)
		{
			recordDependencyOnSingleRelExpr(&myself,
											(Node *) indexInfo->ii_Predicate,
											heapRelationId,
											DEPENDENCY_NORMAL,
											DEPENDENCY_AUTO);
		}
	}

	/*
	 * Advance the command counter so that we can see the newly-entered
	 * catalog tuples for the index.
	 */
	CommandCounterIncrement();

	/*
	 * In bootstrap mode, we have to fill in the index strategy structure with
	 * information from the catalogs.  If we aren't bootstrapping, then the
	 * relcache entry has already been rebuilt thanks to sinval update during
	 * CommandCounterIncrement.
	 */
	if (IsBootstrapProcessingMode())
		RelationInitIndexAccessInfo(indexRelation);
	else
		Assert(indexRelation->rd_indexcxt != NULL);

	/*
	 * If this is bootstrap (initdb) time, then we don't actually fill in the
	 * index yet.  We'll be creating more indexes and classes later, so we
	 * delay filling them in until just before we're done with bootstrapping.
	 * Similarly, if the caller specified skip_build then filling the index is
	 * delayed till later (ALTER TABLE can save work in some cases with this).
	 * Otherwise, we call the AM routine that constructs the index.
	 *
	 * In normal processing mode, the heap and index relations are closed, but
	 * we continue to hold the ShareLock on the heap and the exclusive lock on
	 * the index that we acquired above, until end of transaction.
	 */
	if (IsBootstrapProcessingMode())
	{
		index_register(heapRelationId, indexRelationId, indexInfo);
		/* XXX shouldn't we close the heap and index rels here? */
	}
	else if (skip_build)
	{
		/* caller is responsible for filling the index later on */
		relation_close(indexRelation, NoLock);
		heap_close(heapRelation, NoLock);
	}
	else
	{
		index_build(heapRelation, indexRelation, indexInfo);
		/* index_build closes the passed rels */
	}

	return indexRelationId;
}

/*
 *		index_drop
 *
 * NOTE: this routine should now only be called through performDeletion(),
 * else associated dependencies won't be cleaned up.
 */
void
index_drop(Oid indexId)
{
	Oid			heapId;
	Relation	userHeapRelation;
	Relation	userIndexRelation;
	Relation	indexRelation;
	HeapTuple	tuple;
	bool		hasexprs;

	/*
	 * To drop an index safely, we must grab exclusive lock on its parent
	 * table; otherwise there could be other backends using the index!
	 * Exclusive lock on the index alone is insufficient because another
	 * backend might be in the midst of devising a query plan that will use
	 * the index.  The parser and planner take care to hold an appropriate
	 * lock on the parent table while working, but having them hold locks on
	 * all the indexes too seems overly expensive.	We do grab exclusive lock
	 * on the index too, just to be safe. Both locks must be held till end of
	 * transaction, else other backends will still see this index in pg_index.
	 */
	heapId = IndexGetRelation(indexId);
	userHeapRelation = heap_open(heapId, AccessExclusiveLock);

	userIndexRelation = index_open(indexId);
	LockRelation(userIndexRelation, AccessExclusiveLock);

	/*
	 * Schedule physical removal of the file
	 */
	RelationOpenSmgr(userIndexRelation);
	smgrscheduleunlink(userIndexRelation->rd_smgr,
					   userIndexRelation->rd_istemp);

	/*
	 * Close and flush the index's relcache entry, to ensure relcache doesn't
	 * try to rebuild it while we're deleting catalog entries. We keep the
	 * lock though.
	 */
	index_close(userIndexRelation);

	RelationForgetRelation(indexId);

	/*
	 * fix INDEX relation, and check for expressional index
	 */
	indexRelation = heap_open(IndexRelationId, RowExclusiveLock);

	tuple = SearchSysCache(INDEXRELID,
						   ObjectIdGetDatum(indexId),
						   0, 0, 0);
	if (!HeapTupleIsValid(tuple))
		elog(ERROR, "cache lookup failed for index %u", indexId);

	hasexprs = !heap_attisnull(tuple, Anum_pg_index_indexprs);

	simple_heap_delete(indexRelation, &tuple->t_self);

	ReleaseSysCache(tuple);
	heap_close(indexRelation, RowExclusiveLock);

	/*
	 * if it has any expression columns, we might have stored statistics about
	 * them.
	 */
	if (hasexprs)
		RemoveStatistics(indexId, 0);

	/*
	 * fix ATTRIBUTE relation
	 */
	DeleteAttributeTuples(indexId);

	/*
	 * fix RELATION relation
	 */
	DeleteRelationTuple(indexId);

	/*
	 * We are presently too lazy to attempt to compute the new correct value
	 * of relhasindex (the next VACUUM will fix it if necessary). So there is
	 * no need to update the pg_class tuple for the owning relation. But we
	 * must send out a shared-cache-inval notice on the owning relation to
	 * ensure other backends update their relcache lists of indexes.
	 */
	CacheInvalidateRelcache(userHeapRelation);

	/*
	 * Close owning rel, but keep lock
	 */
	heap_close(userHeapRelation, NoLock);
}

/* ----------------------------------------------------------------
 *						index_build support
 * ----------------------------------------------------------------
 */

/* ----------------
 *		BuildIndexInfo
 *			Construct an IndexInfo record for an open index
 *
 * IndexInfo stores the information about the index that's needed by
 * FormIndexDatum, which is used for both index_build() and later insertion
 * of individual index tuples.	Normally we build an IndexInfo for an index
 * just once per command, and then use it for (potentially) many tuples.
 * ----------------
 */
IndexInfo *
BuildIndexInfo(Relation index)
{
	IndexInfo  *ii = makeNode(IndexInfo);
	Form_pg_index indexStruct = index->rd_index;
	int			i;
	int			numKeys;

	/* check the number of keys, and copy attr numbers into the IndexInfo */
	numKeys = indexStruct->indnatts;
	if (numKeys < 1 || numKeys > INDEX_MAX_KEYS)
		elog(ERROR, "invalid indnatts %d for index %u",
			 numKeys, RelationGetRelid(index));
	ii->ii_NumIndexAttrs = numKeys;
	for (i = 0; i < numKeys; i++)
		ii->ii_KeyAttrNumbers[i] = indexStruct->indkey.values[i];

	/* fetch any expressions needed for expressional indexes */
	ii->ii_Expressions = RelationGetIndexExpressions(index);