Index: doc/src/sgml/mvcc.sgml
===================================================================
RCS file: /var/lib/cvs/pgsql/doc/src/sgml/mvcc.sgml,v
retrieving revision 2.47
diff -c -r2.47 mvcc.sgml
*** doc/src/sgml/mvcc.sgml	26 Feb 2005 18:37:17 -0000	2.47
--- doc/src/sgml/mvcc.sgml	23 Mar 2005 00:46:36 -0000
***************
*** 654,661 ****
  	</para>
  
  	<para>
!          This lock mode is not automatically acquired by any
!          <productname>PostgreSQL</productname> command.
  	</para>
         </listitem>
        </varlistentry>
--- 654,661 ----
  	</para>
  
  	<para>
!      Acquired by <command>CREATE TRIGGER</command> and <command>ALTER
!      TABLE ADD FOREIGN KEY</command>.
  	</para>
         </listitem>
        </varlistentry>
Index: src/backend/commands/tablecmds.c
===================================================================
RCS file: /var/lib/cvs/pgsql/src/backend/commands/tablecmds.c,v
retrieving revision 1.148
diff -c -r1.148 tablecmds.c
*** src/backend/commands/tablecmds.c	20 Mar 2005 22:00:52 -0000	1.148
--- src/backend/commands/tablecmds.c	23 Mar 2005 00:49:08 -0000
***************
*** 3829,3841 ****
  	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.)
  	 */
! 	pkrel = heap_openrv(fkconstraint->pktable, AccessExclusiveLock);
  
  	/*
  	 * Validity and permissions checks
--- 3829,3839 ----
  	Oid			constrOid;
  
  	/*
! 	 * Grab a lock on the pk table, so that someone doesn't delete
! 	 * rows out from under us; ShareRowExclusive should be good
! 	 * enough.
  	 */
! 	pkrel = heap_openrv(fkconstraint->pktable, ShareRowExclusiveLock);
  
  	/*
  	 * Validity and permissions checks
Index: src/backend/commands/trigger.c
===================================================================
RCS file: /var/lib/cvs/pgsql/src/backend/commands/trigger.c,v
retrieving revision 1.178
diff -c -r1.178 trigger.c
*** src/backend/commands/trigger.c	20 Mar 2005 23:40:24 -0000	1.178
--- src/backend/commands/trigger.c	23 Mar 2005 00:49:53 -0000
***************
*** 87,93 ****
  	ObjectAddress myself,
  				referenced;
  
! 	rel = heap_openrv(stmt->relation, AccessExclusiveLock);
  
  	if (stmt->constrrel != NULL)
  		constrrelid = RangeVarGetRelid(stmt->constrrel, false);
--- 87,98 ----
  	ObjectAddress myself,
  				referenced;
  
!     /*
!      * We need to prevent concurrent CREATE TRIGGER commands, as well
!      * as concurrent table modifications (INSERT, DELETE, UPDATE), so
!      * ShareRowExclusive is sufficient.
!      */
! 	rel = heap_openrv(stmt->relation, ShareRowExclusiveLock);
  
  	if (stmt->constrrel != NULL)
  		constrrelid = RangeVarGetRelid(stmt->constrrel, false);