index.c

来自「PostgreSQL7.4.6 for Linux」· C语言 代码 · 共 1,784 行 · 第 1/4 页

	/* update the indexes on pg_index */
	CatalogUpdateIndexes(pg_index, tuple);

	/*
	 * close the relation and free the tuple
	 */
	heap_close(pg_index, RowExclusiveLock);
	heap_freetuple(tuple);
}


/* ----------------------------------------------------------------
 *		index_create
 *
 * Returns OID of the created index.
 * ----------------------------------------------------------------
 */
Oid
index_create(Oid heapRelationId,
			 const char *indexRelationName,
			 IndexInfo *indexInfo,
			 Oid accessMethodObjectId,
			 Oid *classObjectId,
			 bool primary,
			 bool isconstraint,
			 bool allow_system_table_mods)
{
	Relation	heapRelation;
	Relation	indexRelation;
	TupleDesc	indexTupDesc;
	bool		shared_relation;
	Oid			namespaceId;
	Oid			indexoid;
	int			i;

	/*
	 * Only SELECT ... FOR UPDATE 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.	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);

	/*
	 * 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,
								indexTupDesc,
								shared_relation,
								true,
								allow_system_table_mods);

	/* Fetch the relation OID assigned by heap_create */
	indexoid = 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 = GetUserId();
	indexRelation->rd_rel->relam = accessMethodObjectId;
	indexRelation->rd_rel->relkind = RELKIND_INDEX;
	indexRelation->rd_rel->relhasoids = false;

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

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

	/*
	 * 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(indexoid, 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 = RelOid_pg_class;
		myself.objectId = indexoid;
		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 = get_system_catalog_relid(ConstraintRelationName);
			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 = RelOid_pg_class;
					referenced.objectId = heapRelationId;
					referenced.objectSubId = indexInfo->ii_KeyAttrNumbers[i];

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

		/* Store dependency on operator classes */
		referenced.classId = get_system_catalog_relid(OperatorClassRelationName);
		for (i = 0; i < indexInfo->ii_NumIndexAttrs; i++)
		{
			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);
		}
	}

	/*
	 * Fill in the index strategy structure with information from the
	 * catalogs.  First we must advance the command counter so that we
	 * will see the newly-entered index catalog tuples.
	 */
	CommandCounterIncrement();

	RelationInitIndexAccessInfo(indexRelation);

	/*
	 * 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.  Otherwise, we call the routine that constructs the
	 * index.
	 *
	 * In normal processing mode, the heap and index relations are closed by
	 * index_build() --- 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, indexoid, indexInfo);
		/* XXX shouldn't we close the heap and index rels here? */
	}
	else
		index_build(heapRelation, indexRelation, indexInfo);

	return indexoid;
}

/*
 *		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;
	int			i;

	Assert(OidIsValid(indexId));

	/*
	 * 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 complex.	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);

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

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

	/*
	 * fix INDEX relation
	 */
	indexRelation = heap_openr(IndexRelationName, RowExclusiveLock);

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

	simple_heap_delete(indexRelation, &tuple->t_self);

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

	/*
	 * flush buffer cache and physically remove the file
	 */
	i = FlushRelationBuffers(userIndexRelation, (BlockNumber) 0);
	if (i < 0)
		elog(ERROR, "FlushRelationBuffers returned %d", i);

	smgrunlink(DEFAULT_SMGR, userIndexRelation);

	/*
	 * 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(heapId);

	/*
	 * Close rels, but keep locks
	 */
	index_close(userIndexRelation);
	heap_close(userHeapRelation, NoLock);

	RelationForgetRelation(indexId);
}

/* ----------------------------------------------------------------
 *						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[i];

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

	/* fetch index predicate if any */
	ii->ii_Predicate = RelationGetIndexPredicate(index);
	ii->ii_PredicateState = NIL;

	/* other info */
	ii->ii_Unique = indexStruct->indisunique;

	return ii;
}

/* ----------------
 *		FormIndexDatum
 *			Construct Datum[] and nullv[] arrays for a new index tuple.
 *
 *	indexInfo		Info about the index
 *	heapTuple		Heap tuple for which we must prepare an index entry
 *	heapDescriptor	tupledesc for heap tuple
 *	estate			executor state for evaluating any index expressions
 *	datum			Array of index Datums (output area)
 *	nullv			Array of is-null indicators (output area)
 *
 * When there are no index expressions, estate may be NULL.  Otherwise it
 * must be supplied, *and* the ecxt_scantuple slot of its per-tuple expr
 * context must point to the heap tuple passed in.
 *
 * For largely historical reasons, we don't actually call index_formtuple()