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Code review for ALTER TRIGGER RENAME patch: make better use of index,

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don't scribble on tuple returned by table scan.
This commit is contained in:
Tom Lane 2002-04-30 01:24:57 +00:00
parent 857661ba2e
commit 4c25a0655b
2 changed files with 44 additions and 48 deletions
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89
src/backend/commands/trigger.c
View File

@ -7,7 +7,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/commands/trigger.c,v 1.116 2002/04/27 03:45:02 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/commands/trigger.c,v 1.117 2002/04/30 01:24:57 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -514,8 +514,7 @@ RelationRemoveTriggers(Relation rel)
* for name conflict (within rel)
* for original trigger (if not arg)
* modify tgname in trigger tuple
* insert modified trigger in trigger catalog
* delete original trigger from trigger catalog
* update row in catalog
*/
void
renametrig(Oid relid,
@ -526,8 +525,7 @@ renametrig(Oid relid,
Relation tgrel;
HeapTuple tuple;
SysScanDesc tgscan;
ScanKeyData key;
bool found = FALSE;
ScanKeyData key[2];
Relation idescs[Num_pg_trigger_indices];
/*
@ -550,70 +548,69 @@ renametrig(Oid relid,
/*
* First pass -- look for name conflict
*/
ScanKeyEntryInitialize(&key, 0,
ScanKeyEntryInitialize(&key[0], 0,
Anum_pg_trigger_tgrelid,
F_OIDEQ,
ObjectIdGetDatum(relid));
ScanKeyEntryInitialize(&key[1], 0,
Anum_pg_trigger_tgname,
F_NAMEEQ,
PointerGetDatum(newname));
tgscan = systable_beginscan(tgrel, TriggerRelidNameIndex, true,
SnapshotNow, 1, &key);
while (HeapTupleIsValid(tuple = systable_getnext(tgscan)))
{
Form_pg_trigger pg_trigger = (Form_pg_trigger) GETSTRUCT(tuple);
if (namestrcmp(&(pg_trigger->tgname), newname) == 0)
elog(ERROR, "renametrig: trigger %s already defined on relation %s",
newname, RelationGetRelationName(targetrel));
}
SnapshotNow, 2, key);
if (HeapTupleIsValid(tuple = systable_getnext(tgscan)))
elog(ERROR, "renametrig: trigger %s already defined on relation %s",
newname, RelationGetRelationName(targetrel));
systable_endscan(tgscan);
/*
* Second pass -- look for trigger existing with oldname and update
*/
ScanKeyEntryInitialize(&key, 0,
ScanKeyEntryInitialize(&key[0], 0,
Anum_pg_trigger_tgrelid,
F_OIDEQ,
ObjectIdGetDatum(relid));
ScanKeyEntryInitialize(&key[1], 0,
Anum_pg_trigger_tgname,
F_NAMEEQ,
PointerGetDatum(oldname));
tgscan = systable_beginscan(tgrel, TriggerRelidNameIndex, true,
SnapshotNow, 1, &key);
while (HeapTupleIsValid(tuple = systable_getnext(tgscan)))
SnapshotNow, 2, key);
if (HeapTupleIsValid(tuple = systable_getnext(tgscan)))
{
Form_pg_trigger pg_trigger = (Form_pg_trigger) GETSTRUCT(tuple);
/*
* Update pg_trigger tuple with new tgname.
*/
tuple = heap_copytuple(tuple); /* need a modifiable copy */
if (namestrcmp(&(pg_trigger->tgname), oldname) == 0)
{
/*
* Update pg_trigger tuple with new tgname.
* (Scribbling on tuple is OK because it's a copy...)
*/
namestrcpy(&(pg_trigger->tgname), newname);
simple_heap_update(tgrel, &tuple->t_self, tuple);
namestrcpy(&((Form_pg_trigger) GETSTRUCT(tuple))->tgname, newname);
/*
* keep system catalog indices current
*/
CatalogOpenIndices(Num_pg_trigger_indices, Name_pg_trigger_indices, idescs);
CatalogIndexInsert(idescs, Num_pg_trigger_indices, tgrel, tuple);
CatalogCloseIndices(Num_pg_trigger_indices, idescs);
simple_heap_update(tgrel, &tuple->t_self, tuple);
/*
* Invalidate relation's relcache entry so that other
* backends (and this one too!) are sent SI message to make them
* rebuild relcache entries.
*/
CacheInvalidateRelcache(relid);
/*
* keep system catalog indices current
*/
CatalogOpenIndices(Num_pg_trigger_indices, Name_pg_trigger_indices, idescs);
CatalogIndexInsert(idescs, Num_pg_trigger_indices, tgrel, tuple);
CatalogCloseIndices(Num_pg_trigger_indices, idescs);
found = TRUE;
break;
}
/*
* Invalidate relation's relcache entry so that other backends (and
* this one too!) are sent SI message to make them rebuild relcache
* entries. (Ideally this should happen automatically...)
*/
CacheInvalidateRelcache(relid);
}
else
{
elog(ERROR, "renametrig: trigger %s not defined on relation %s",
oldname, RelationGetRelationName(targetrel));
}
systable_endscan(tgscan);
heap_close(tgrel, RowExclusiveLock);
if (!found)
elog(ERROR, "renametrig: trigger %s not defined on relation %s",
oldname, RelationGetRelationName(targetrel));
/*
* Close rel, but keep exclusive lock!
*/

3
src/include/commands/tablecmds.h
View File

@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: tablecmds.h,v 1.3 2002/04/26 19:29:47 tgl Exp $
* $Id: tablecmds.h,v 1.4 2002/04/30 01:24:52 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -15,7 +15,6 @@
#define TABLECMDS_H
#include "nodes/parsenodes.h"
#include "utils/inval.h"
extern void AlterTableAddColumn(Oid myrelid, bool inherits,
ColumnDef *colDef);