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Revert changes to CREATE TRIGGER and ALTER TABLE ADD FOREIGN KEY locking,

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per request from Tom.
This commit is contained in:
Neil Conway 2005-03-24 00:03:26 +00:00
parent 8abba63859
commit 50ce8ab9fc
3 changed files with 13 additions and 21 deletions
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9
doc/src/sgml/mvcc.sgml
View File

@ -1,5 +1,5 @@
<!-- <!--
$PostgreSQL: pgsql/doc/src/sgml/mvcc.sgml,v 2.48 2005/03/23 07:44:56 neilc Exp $ $PostgreSQL: pgsql/doc/src/sgml/mvcc.sgml,v 2.49 2005/03/24 00:03:18 neilc Exp $
--> -->
<chapter id="mvcc"> <chapter id="mvcc">
@ -677,10 +677,9 @@ SELECT SUM(value) FROM mytab WHERE class = 2;
</para> </para>
<para> <para>
Acquired by <command>CREATE TRIGGER</command> and This lock mode is not automatically acquired on user tables by any
<command>ALTER TABLE ADD FOREIGN KEY</command>. This lock <productname>PostgreSQL</productname> command. However it is
mode can also be acquired on certain system catalogs in some acquired on certain system catalogs in some operations.
operations.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>

14
src/backend/commands/tablecmds.c
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@ -8,7 +8,7 @@
* *
* *
* IDENTIFICATION * IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.149 2005/03/23 07:44:57 neilc Exp $ * $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.150 2005/03/24 00:03:22 neilc Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -3829,13 +3829,13 @@ ATAddForeignKeyConstraint(AlteredTableInfo *tab, Relation rel,
Oid constrOid; Oid constrOid;
/* /*
* Grab a lock on the pk table, so that someone doesn't delete * Grab an exclusive lock on the pk table, so that someone doesn't
* rows out from under us. We will eventually need to add triggers * delete rows out from under us. (Although a lesser lock would do for
* to the table, at which point we'll need to an ExclusiveLock -- * that purpose, we'll need exclusive lock anyway to add triggers to
* therefore we grab an ExclusiveLock now to prevent possible * the pk table; trying to start with a lesser lock will just create a
* deadlock. * risk of deadlock.)
*/ */
pkrel = heap_openrv(fkconstraint->pktable, ExclusiveLock); pkrel = heap_openrv(fkconstraint->pktable, AccessExclusiveLock);
/* /*
* Validity and permissions checks * Validity and permissions checks

11
src/backend/commands/trigger.c
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1994, Regents of the University of California * Portions Copyright (c) 1994, Regents of the University of California
* *
* IDENTIFICATION * IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.179 2005/03/23 07:44:57 neilc Exp $ * $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.180 2005/03/24 00:03:26 neilc Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -87,14 +87,7 @@ CreateTrigger(CreateTrigStmt *stmt, bool forConstraint)
ObjectAddress myself, ObjectAddress myself,
referenced; 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) if (stmt->constrrel != NULL)
constrrelid = RangeVarGetRelid(stmt->constrrel, false); constrrelid = RangeVarGetRelid(stmt->constrrel, false);