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Revise mechanism for getting rid of temp tables at backend shutdown.

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Instead of grovelling through pg_class to find them, make use of the
handy dandy dependency mechanism: just delete everything that depends
on our temp schema.  Unlike the pg_class scan, the dependency mechanism
is smart enough to delete things in an order that doesn't fall foul of
any dependency restrictions.  Fixes problem reported by David Heggie:
a temp table with a serial column may cause a backend FATAL exit at
shutdown time, if it chances to try to delete the temp sequence first.
This commit is contained in:
Tom Lane
2003-02-07 01:33:06 +00:00
parent 00f1a41ab2
commit 3acf422316
3 changed files with 157 additions and 88 deletions
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56
src/backend/catalog/namespace.c
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@@ -13,21 +13,17 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/catalog/namespace.c,v 1.45 2003/01/12 18:19:37 petere Exp $
* $Header: /cvsroot/pgsql/src/backend/catalog/namespace.c,v 1.46 2003/02/07 01:33:06 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/heapam.h"
#include "access/xact.h"
#include "catalog/catalog.h"
#include "catalog/catname.h"
#include "catalog/dependency.h"
#include "catalog/heap.h"
#include "catalog/namespace.h"
#include "catalog/pg_conversion.h"
#include "catalog/pg_inherits.h"
#include "catalog/pg_namespace.h"
#include "catalog/pg_opclass.h"
#include "catalog/pg_operator.h"
@@ -42,10 +38,9 @@
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/catcache.h"
#include "utils/fmgroids.h"
#include "utils/guc.h"
#include "utils/inval.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/syscache.h"
@@ -1691,50 +1686,19 @@ AtEOXact_Namespace(bool isCommit)
static void
RemoveTempRelations(Oid tempNamespaceId)
{
Relation pgclass;
HeapScanDesc scan;
HeapTuple tuple;
ScanKeyData key;
ObjectAddress object;
/*
* Scan pg_class to find all the relations in the target namespace.
* Ignore indexes, though, on the assumption that they'll go away when
* their tables are deleted.
*
* NOTE: if there are deletion constraints between temp relations, then
* our CASCADE delete call may cause as-yet-unvisited objects to go
* away. This is okay because we are using SnapshotNow; when the scan
* does reach those pg_class tuples, they'll be ignored as already
* deleted.
* We want to get rid of everything in the target namespace, but not
* the namespace itself (deleting it only to recreate it later would be
* a waste of cycles). We do this by finding everything that has a
* dependency on the namespace.
*/
ScanKeyEntryInitialize(&key, 0x0,
Anum_pg_class_relnamespace,
F_OIDEQ,
ObjectIdGetDatum(tempNamespaceId));
object.classId = get_system_catalog_relid(NamespaceRelationName);
object.objectId = tempNamespaceId;
object.objectSubId = 0;
pgclass = heap_openr(RelationRelationName, AccessShareLock);
scan = heap_beginscan(pgclass, SnapshotNow, 1, &key);
while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
{
switch (((Form_pg_class) GETSTRUCT(tuple))->relkind)
{
case RELKIND_RELATION:
case RELKIND_SEQUENCE:
case RELKIND_VIEW:
object.classId = RelOid_pg_class;
object.objectId = HeapTupleGetOid(tuple);
object.objectSubId = 0;
performDeletion(&object, DROP_CASCADE);
break;
default:
break;
}
}
heap_endscan(scan);
heap_close(pgclass, AccessShareLock);
deleteWhatDependsOn(&object);
}
/*