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Adjust CREATE TRIGGER and ALTER TABLE ... ADD FOREIGN KEY to acquire

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ExclusiveLock rather than AccessExclusiveLock. This will allow concurrent
SELECT queries to proceed on the table. Per discussion with Andrew at
SuperNews.
This commit is contained in:
Neil Conway
2005-03-23 07:44:57 +00:00
parent ac323044cf
commit f30c76ce8d
3 changed files with 21 additions and 13 deletions
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11
src/backend/commands/trigger.c
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.178 2005/03/20 23:40:24 neilc Exp $
* $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.179 2005/03/23 07:44:57 neilc Exp $
*
*-------------------------------------------------------------------------
*/
@ -87,7 +87,14 @@ CreateTrigger(CreateTrigStmt *stmt, bool forConstraint)
ObjectAddress myself,
referenced;
rel = heap_openrv(stmt->relation, AccessExclusiveLock);
/*
* We need to prevent concurrent CREATE TRIGGER commands, as well
* as concurrent table modifications (INSERT, DELETE, UPDATE), so
* acquire an ExclusiveLock -- it should be fine to allow SELECTs
* to proceed. We could perhaps acquire ShareRowExclusiveLock, but
* there seems little gain in allowing SELECT FOR UPDATE.
*/
rel = heap_openrv(stmt->relation, ExclusiveLock);
if (stmt->constrrel != NULL)
constrrelid = RangeVarGetRelid(stmt->constrrel, false);