cluster.c

PostgreSQL7.4.6 for Linux

	object.objectId = OIDNewHeap;
	object.objectSubId = 0;

	/*
	 * The new relation is local to our transaction and we know nothing
	 * depends on it, so DROP_RESTRICT should be OK.
	 */
	performDeletion(&object, DROP_RESTRICT);

	/* performDeletion does CommandCounterIncrement at end */

	/*
	 * Recreate each index on the relation.  We do not need
	 * CommandCounterIncrement() because rebuild_indexes does it.
	 */
	rebuild_indexes(tableOid, indexes);
}

/*
 * Create the new table that we will fill with correctly-ordered data.
 */
static Oid
make_new_heap(Oid OIDOldHeap, const char *NewName)
{
	TupleDesc	OldHeapDesc,
				tupdesc;
	Oid			OIDNewHeap;
	Relation	OldHeap;

	OldHeap = heap_open(OIDOldHeap, AccessExclusiveLock);
	OldHeapDesc = RelationGetDescr(OldHeap);

	/*
	 * Need to make a copy of the tuple descriptor, since
	 * heap_create_with_catalog modifies it.
	 */
	tupdesc = CreateTupleDescCopyConstr(OldHeapDesc);

	OIDNewHeap = heap_create_with_catalog(NewName,
										  RelationGetNamespace(OldHeap),
										  tupdesc,
										  OldHeap->rd_rel->relkind,
										  OldHeap->rd_rel->relisshared,
										  ONCOMMIT_NOOP,
										  allowSystemTableMods);

	/*
	 * Advance command counter so that the newly-created relation's
	 * catalog tuples will be visible to heap_open.
	 */
	CommandCounterIncrement();

	/*
	 * If necessary, create a TOAST table for the new relation. Note that
	 * AlterTableCreateToastTable ends with CommandCounterIncrement(), so
	 * that the TOAST table will be visible for insertion.
	 */
	AlterTableCreateToastTable(OIDNewHeap, true);

	heap_close(OldHeap, NoLock);

	return OIDNewHeap;
}

/*
 * Do the physical copying of heap data.
 */
static void
copy_heap_data(Oid OIDNewHeap, Oid OIDOldHeap, Oid OIDOldIndex)
{
	Relation	NewHeap,
				OldHeap,
				OldIndex;
	IndexScanDesc scan;
	HeapTuple	tuple;

	/*
	 * Open the relations I need. Scan through the OldHeap on the OldIndex
	 * and insert each tuple into the NewHeap.
	 */
	NewHeap = heap_open(OIDNewHeap, AccessExclusiveLock);
	OldHeap = heap_open(OIDOldHeap, AccessExclusiveLock);
	OldIndex = index_open(OIDOldIndex);

	scan = index_beginscan(OldHeap, OldIndex, SnapshotNow, 0, (ScanKey) NULL);

	while ((tuple = index_getnext(scan, ForwardScanDirection)) != NULL)
	{
		/*
		 * We must copy the tuple because heap_insert() will overwrite the
		 * commit-status fields of the tuple it's handed, and the
		 * retrieved tuple will actually be in a disk buffer!  Thus, the
		 * source relation would get trashed, which is bad news if we
		 * abort later on.	(This was a bug in releases thru 7.0)
		 *
		 * Note that the copied tuple will have the original OID, if any, so
		 * this does preserve OIDs.
		 */
		HeapTuple	copiedTuple = heap_copytuple(tuple);

		simple_heap_insert(NewHeap, copiedTuple);

		heap_freetuple(copiedTuple);

		CHECK_FOR_INTERRUPTS();
	}

	index_endscan(scan);

	index_close(OldIndex);
	heap_close(OldHeap, NoLock);
	heap_close(NewHeap, NoLock);
}

/*
 * Get the necessary info about the indexes of the relation and
 * return a list of IndexAttrs structures.
 */
static List *
get_indexattr_list(Relation OldHeap, Oid OldIndex)
{
	List	   *indexes = NIL;
	List	   *indlist;

	/* Ask the relcache to produce a list of the indexes of the old rel */
	foreach(indlist, RelationGetIndexList(OldHeap))
	{
		Oid			indexOID = lfirsto(indlist);
		Relation	oldIndex;
		IndexAttrs *attrs;

		oldIndex = index_open(indexOID);

		attrs = (IndexAttrs *) palloc(sizeof(IndexAttrs));
		attrs->indexOID = indexOID;
		attrs->indexName = pstrdup(NameStr(oldIndex->rd_rel->relname));
		attrs->accessMethodOID = oldIndex->rd_rel->relam;
		attrs->indexInfo = BuildIndexInfo(oldIndex);
		attrs->classOID = (Oid *)
			palloc(sizeof(Oid) * attrs->indexInfo->ii_NumIndexAttrs);
		memcpy(attrs->classOID, oldIndex->rd_index->indclass,
			   sizeof(Oid) * attrs->indexInfo->ii_NumIndexAttrs);
		/* We adjust the isclustered attribute to correct new state */
		attrs->isclustered = (indexOID == OldIndex);

		index_close(oldIndex);

		/*
		 * Cons the gathered data into the list.  We do not care about
		 * ordering, and this is more efficient than append.
		 */
		indexes = lcons(attrs, indexes);
	}

	return indexes;
}

/*
 * Create new indexes and swap the filenodes with old indexes.	Then drop
 * the new index (carrying the old index filenode along).
 */
static void
rebuild_indexes(Oid OIDOldHeap, List *indexes)
{
	List	   *elem;

	foreach(elem, indexes)
	{
		IndexAttrs *attrs = (IndexAttrs *) lfirst(elem);
		Oid			newIndexOID;
		char		newIndexName[NAMEDATALEN];
		ObjectAddress object;
		Form_pg_index index;
		HeapTuple	tuple;
		Relation	pg_index;

		/* Create the new index under a temporary name */
		snprintf(newIndexName, sizeof(newIndexName),
				 "pg_temp_%u", attrs->indexOID);

		/*
		 * The new index will have primary and constraint status set to
		 * false, but since we will only use its filenode it doesn't
		 * matter: after the filenode swap the index will keep the
		 * constraint status of the old index.
		 */
		newIndexOID = index_create(OIDOldHeap, newIndexName,
								attrs->indexInfo, attrs->accessMethodOID,
								   attrs->classOID, false,
								   false, allowSystemTableMods);
		CommandCounterIncrement();

		/* Swap the filenodes. */
		swap_relfilenodes(attrs->indexOID, newIndexOID);

		CommandCounterIncrement();

		/*
		 * Make sure that indisclustered is correct: it should be set only
		 * for the index we just clustered on.
		 */
		pg_index = heap_openr(IndexRelationName, RowExclusiveLock);
		tuple = SearchSysCacheCopy(INDEXRELID,
								   ObjectIdGetDatum(attrs->indexOID),
								   0, 0, 0);
		if (!HeapTupleIsValid(tuple))
			elog(ERROR, "cache lookup failed for index %u", attrs->indexOID);
		index = (Form_pg_index) GETSTRUCT(tuple);
		if (index->indisclustered != attrs->isclustered)
		{
			index->indisclustered = attrs->isclustered;
			simple_heap_update(pg_index, &tuple->t_self, tuple);
			CatalogUpdateIndexes(pg_index, tuple);
		}
		heap_freetuple(tuple);
		heap_close(pg_index, RowExclusiveLock);

		/* Destroy new index with old filenode */
		object.classId = RelOid_pg_class;
		object.objectId = newIndexOID;
		object.objectSubId = 0;

		/*
		 * The relation is local to our transaction and we know nothing
		 * depends on it, so DROP_RESTRICT should be OK.
		 */
		performDeletion(&object, DROP_RESTRICT);

		/* performDeletion does CommandCounterIncrement() at its end */
	}
}

/*
 * Swap the relfilenodes for two given relations.
 *
 * Also swap any TOAST links, so that the toast data moves along with
 * the main-table data.
 */
static void
swap_relfilenodes(Oid r1, Oid r2)
{
	Relation	relRelation,
				rel;
	HeapTuple	reltup1,
				reltup2;
	Form_pg_class relform1,
				relform2;
	Oid			swaptemp;
	int			i;
	CatalogIndexState indstate;

	/* We need writable copies of both pg_class tuples. */
	relRelation = heap_openr(RelationRelationName, RowExclusiveLock);

	reltup1 = SearchSysCacheCopy(RELOID,
								 ObjectIdGetDatum(r1),
								 0, 0, 0);
	if (!HeapTupleIsValid(reltup1))
		elog(ERROR, "cache lookup failed for relation %u", r1);
	relform1 = (Form_pg_class) GETSTRUCT(reltup1);

	reltup2 = SearchSysCacheCopy(RELOID,
								 ObjectIdGetDatum(r2),
								 0, 0, 0);
	if (!HeapTupleIsValid(reltup2))
		elog(ERROR, "cache lookup failed for relation %u", r2);
	relform2 = (Form_pg_class) GETSTRUCT(reltup2);

	/*
	 * The buffer manager gets confused if we swap relfilenodes for
	 * relations that are not both local or non-local to this transaction.
	 * Flush the buffers on both relations so the buffer manager can
	 * forget about'em.  (XXX this might not be necessary anymore?)
	 */
	rel = relation_open(r1, NoLock);
	i = FlushRelationBuffers(rel, 0);
	if (i < 0)
		elog(ERROR, "FlushRelationBuffers returned %d", i);
	relation_close(rel, NoLock);

	rel = relation_open(r2, NoLock);
	i = FlushRelationBuffers(rel, 0);
	if (i < 0)
		elog(ERROR, "FlushRelationBuffers returned %d", i);
	relation_close(rel, NoLock);

	/*
	 * Actually swap the filenode and TOAST fields in the two tuples
	 */
	swaptemp = relform1->relfilenode;
	relform1->relfilenode = relform2->relfilenode;
	relform2->relfilenode = swaptemp;

	swaptemp = relform1->reltoastrelid;
	relform1->reltoastrelid = relform2->reltoastrelid;
	relform2->reltoastrelid = swaptemp;

	/* we should not swap reltoastidxid */

	/* swap size statistics too, since new rel has freshly-updated stats */
	{
		int4		swap_pages;
		float4		swap_tuples;

		swap_pages = relform1->relpages;
		relform1->relpages = relform2->relpages;
		relform2->relpages = swap_pages;

		swap_tuples = relform1->reltuples;
		relform1->reltuples = relform2->reltuples;
		relform2->reltuples = swap_tuples;
	}

	/* Update the tuples in pg_class */
	simple_heap_update(relRelation, &reltup1->t_self, reltup1);
	simple_heap_update(relRelation, &reltup2->t_self, reltup2);

	/* Keep system catalogs current */
	indstate = CatalogOpenIndexes(relRelation);
	CatalogIndexInsert(indstate, reltup1);
	CatalogIndexInsert(indstate, reltup2);
	CatalogCloseIndexes(indstate);

	/*
	 * If we have toast tables associated with the relations being
	 * swapped, change their dependency links to re-associate them with
	 * their new owning relations.	Otherwise the wrong one will get
	 * dropped ...
	 *
	 * NOTE: it is possible that only one table has a toast table; this can
	 * happen in CLUSTER if there were dropped columns in the old table.
	 *
	 * NOTE: at present, a TOAST table's only dependency is the one on its
	 * owning table.  If more are ever created, we'd need to use something
	 * more selective than deleteDependencyRecordsFor() to get rid of only
	 * the link we want.
	 */
	if (relform1->reltoastrelid || relform2->reltoastrelid)
	{
		ObjectAddress baseobject,
					toastobject;
		long		count;

		/* Delete old dependencies */
		if (relform1->reltoastrelid)
		{
			count = deleteDependencyRecordsFor(RelOid_pg_class,
											   relform1->reltoastrelid);
			if (count != 1)
				elog(ERROR, "expected one dependency record for TOAST table, found %ld",
					 count);
		}
		if (relform2->reltoastrelid)
		{
			count = deleteDependencyRecordsFor(RelOid_pg_class,
											   relform2->reltoastrelid);
			if (count != 1)
				elog(ERROR, "expected one dependency record for TOAST table, found %ld",
					 count);
		}

		/* Register new dependencies */
		baseobject.classId = RelOid_pg_class;
		baseobject.objectSubId = 0;
		toastobject.classId = RelOid_pg_class;
		toastobject.objectSubId = 0;

		if (relform1->reltoastrelid)
		{
			baseobject.objectId = r1;
			toastobject.objectId = relform1->reltoastrelid;
			recordDependencyOn(&toastobject, &baseobject, DEPENDENCY_INTERNAL);
		}

		if (relform2->reltoastrelid)
		{
			baseobject.objectId = r2;
			toastobject.objectId = relform2->reltoastrelid;
			recordDependencyOn(&toastobject, &baseobject, DEPENDENCY_INTERNAL);
		}
	}

	/*
	 * Blow away the old relcache entries now.	We need this kluge because
	 * relcache.c indexes relcache entries by rd_node as well as OID. It
	 * will get confused if it is asked to (re)build an entry with a new
	 * rd_node value when there is still another entry laying about with
	 * that same rd_node value.  (Fortunately, since one of the entries is
	 * local in our transaction, it's sufficient to clear out our own
	 * relcache this way; the problem cannot arise for other backends when
	 * they see our update on the non-local relation.)
	 */
	RelationForgetRelation(r1);
	RelationForgetRelation(r2);

	/* Clean up. */
	heap_freetuple(reltup1);
	heap_freetuple(reltup2);

	heap_close(relRelation, RowExclusiveLock);
}

/*
 * Get a list of tables that the current user owns and
 * have indisclustered set.  Return the list in a List * of rvsToCluster
 * with the tableOid and the indexOid on which the table is already
 * clustered.
 */
static List *
get_tables_to_cluster(MemoryContext cluster_context)
{
	Relation	indRelation;
	HeapScanDesc scan;
	ScanKeyData entry;
	HeapTuple	indexTuple;
	Form_pg_index index;
	MemoryContext old_context;
	RelToCluster *rvtc;
	List	   *rvs = NIL;

	/*
	 * Get all indexes that have indisclustered set and are owned by
	 * appropriate user. System relations or nailed-in relations cannot
	 * ever have indisclustered set, because CLUSTER will refuse to set it
	 * when called with one of them as argument.
	 */
	indRelation = relation_openr(IndexRelationName, AccessShareLock);
	ScanKeyEntryInitialize(&entry, 0,
						   Anum_pg_index_indisclustered,
						   F_BOOLEQ,
						   BoolGetDatum(true));
	scan = heap_beginscan(indRelation, SnapshotNow, 1, &entry);
	while ((indexTuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
	{
		index = (Form_pg_index) GETSTRUCT(indexTuple);

		if (!pg_class_ownercheck(index->indrelid, GetUserId()))
			continue;

		/*
		 * We have to build the list in a different memory context so it
		 * will survive the cross-transaction processing
		 */
		old_context = MemoryContextSwitchTo(cluster_context);

		rvtc = (RelToCluster *) palloc(sizeof(RelToCluster));
		rvtc->tableOid = index->indrelid;
		rvtc->indexOid = index->indexrelid;
		rvs = lcons(rvtc, rvs);

		MemoryContextSwitchTo(old_context);
	}
	heap_endscan(scan);

	relation_close(indRelation, AccessShareLock);

	return rvs;
}