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pg_trigger's index on tgrelid is replaced by a unique index on

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(tgrelid, tgname).  This provides an additional check on trigger name
uniqueness per-table (which was already enforced by the code anyway).
With this change, RelationBuildTriggers will read the triggers in
order by tgname, since it's scanning using this index.  Since a
predictable trigger ordering has been requested for some time, document
this behavior as a feature.  Also document that rules fire in name
order, since yesterday's changes to pg_rewrite indexing cause that too.
This commit is contained in:
Tom Lane
2002-04-19 16:36:08 +00:00
parent 87d00363cb
commit 201737168c
11 changed files with 230 additions and 172 deletions
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23
src/backend/commands/comment.c
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@ -7,7 +7,7 @@
* Copyright (c) 1999-2001, PostgreSQL Global Development Group
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/commands/comment.c,v 1.42 2002/04/18 20:01:09 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/commands/comment.c,v 1.43 2002/04/19 16:36:08 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -753,7 +753,7 @@ CommentTrigger(List *qualname, char *comment)
Relation pg_trigger,
relation;
HeapTuple triggertuple;
HeapScanDesc scan;
SysScanDesc scan;
ScanKeyData entry[2];
Oid oid;
@ -774,17 +774,22 @@ CommentTrigger(List *qualname, char *comment)
elog(ERROR, "you are not permitted to comment on trigger '%s' for relation '%s'",
trigname, RelationGetRelationName(relation));
/* Fetch the trigger oid from pg_trigger */
/*
* Fetch the trigger tuple from pg_trigger. There can be only one
* because of the unique index.
*/
pg_trigger = heap_openr(TriggerRelationName, AccessShareLock);
ScanKeyEntryInitialize(&entry[0], 0x0, Anum_pg_trigger_tgrelid,
ScanKeyEntryInitialize(&entry[0], 0x0,
Anum_pg_trigger_tgrelid,
F_OIDEQ,
ObjectIdGetDatum(RelationGetRelid(relation)));
ScanKeyEntryInitialize(&entry[1], 0x0, Anum_pg_trigger_tgname,
ScanKeyEntryInitialize(&entry[1], 0x0,
Anum_pg_trigger_tgname,
F_NAMEEQ,
CStringGetDatum(trigname));
scan = heap_beginscan(pg_trigger, 0, SnapshotNow, 2, entry);
triggertuple = heap_getnext(scan, 0);
scan = systable_beginscan(pg_trigger, TriggerRelidNameIndex, true,
SnapshotNow, 2, entry);
triggertuple = systable_getnext(scan);
/* If no trigger exists for the relation specified, notify user */
@ -794,7 +799,7 @@ CommentTrigger(List *qualname, char *comment)
oid = triggertuple->t_data->t_oid;
heap_endscan(scan);
systable_endscan(scan);
/* Create the comments with the pg_trigger oid */