On Wed, 2 Dec 2015 09:31:44 -0800 Christophe Pettus <x...@thebuild.com> wrote: > > On Dec 2, 2015, at 9:25 AM, Bill Moran <wmo...@potentialtech.com> wrote: > > > No. See the section on row level locks here: > > http://www.postgresql.org/docs/9.4/static/explicit-locking.html > > That wasn't quite my question. I'm familiar with the row-level locking and > the locking messages in general, but this message implies there is such a > thing as an AccessExclusiveLock on a tuple, which is new to me. I wasn't > able to produce this message experimentally doing various combinations of > UPDATE statements and SELECT FOR UPDATEs, or even with explicit LOCK ACCESS > EXCLUSIVE MODE, thus the question.
First off, that documentation page _does_ answer your question. Secondly, there is a config setting: log_lock_waits, which is disabled by default. The message won't appear if that is off, so if you're testing on a different install than where the incident happened, that could be part of the problem. Finally, the following sequence triggers the message: create table test1 (data int); insert into test1 values (1); Connection 1: begin; select * from test1 where data = 1 for update; Connection 2: select * from test1 where data = 1 for update; Then wait for a little while and the message will be logged. -- Bill Moran -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
