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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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14
src/backend/commands/tablecmds.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.148 2005/03/20 22:00:52 tgl Exp $
* $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.149 2005/03/23 07:44:57 neilc Exp $
*
*-------------------------------------------------------------------------
*/
@ -3829,13 +3829,13 @@ ATAddForeignKeyConstraint(AlteredTableInfo *tab, Relation rel,
Oid constrOid;
/*
* Grab an exclusive lock on the pk table, so that someone doesn't
* delete rows out from under us. (Although a lesser lock would do for
* that purpose, we'll need exclusive lock anyway to add triggers to
* the pk table; trying to start with a lesser lock will just create a
* risk of deadlock.)
* Grab a lock on the pk table, so that someone doesn't delete
* rows out from under us. We will eventually need to add triggers
* to the table, at which point we'll need to an ExclusiveLock --
* therefore we grab an ExclusiveLock now to prevent possible
* deadlock.
*/
pkrel = heap_openrv(fkconstraint->pktable, AccessExclusiveLock);
pkrel = heap_openrv(fkconstraint->pktable, ExclusiveLock);
/*
* Validity and permissions checks