On Wed, 2011-06-29 at 16:39 -0400, Bill Moran wrote: > In response to Aleksey Tsalolikhin <atsaloli.t...@gmail.com>: > > > > We use the fine Bucardo check_postgres Nagios plugin, > > and it reported a "CRITICAL" level spike in database locks > > (171 locks). > > > > I looked closely at my database logs and found an even bigger spike > > just a few minutes earlier (208 locks). > > > > I saw 8 EXCLUSIVE locks on table X. All of these queries completed > > within 5 seconds. (I know that because they do not appear in my > > slow query log.) > > What manner did you use to determine this? It's not possible to have > multiple table-level EXCLUSIVE locks on a single table, since a single > table level EXCLUSIVE lock will cause other lock attempts to block. > However, it's possible to have multiple row-level EXCLUSIVE locks, 1 > per row. Did the mysterious magic that you used to determine that > there were 8 EXCLUSIVE locks tell you whether they were table level > or row level? If they're table level, then something is wrong either > with PostgreSQL or your magic. If they're row level, then that's > hardly unusual. >
You can have multiple EXCLUSIVE LOCKs on the same table, but only one will be granted. See granted column in pg_locks catalog table. -- Guillaume http://blog.guillaume.lelarge.info http://www.dalibo.com -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
