Malcolm McLean wrote:
Richard Huxton wrote:
Malcolm McLean wrote:
I tested this theory by stopping java applications that were
connected
to the database and all other connections that were using
transactions
and the full vacuum was still unable to remove the dead rows.
What I'm still wondering about, is why the dead row count rises
incredibly high, then all of a sudden drops to 0 again when the java
apps never stop running.
Are you certain there's no open transaction? Perhaps keep an eye on
SELECT * FROM pg_stat_activity - there might be something you don't
know
about.
Okay, I just stopped all java processes again and all pg_stat_activity
returned were IDLE's and no IDLE in transactions. The strange this is
that a cluster command removes the dead rows, and this can only be run
when all the java apps have been stopped.
Well, both cluster and vacuum full will require a lock on the table. But
they're more or less doing the same thing, so why the one should work
and the other not I don't know.
If it was the autovacuum interfering, I'd expect a lock failure.
I doubt autovacuum is interfering, I think it is the process that is
clearing the dead rows. If that is the case, then why is only autovacuum
able to clear them and not a manual vacuum.
Makes no sense to me - autovacuum has no magic about it, it just runs
vacuum.
You've got the permissions to vacuum the table, otherwise you'd get an
error. You've checked for transactions in pg_stat_activity. Don't see
how it's worth checking pg_locks if you don't have any transactions.
This one's puzzling me.
I've had a quick look at the release notes for 8.1.x and can't see
anything obvious on this issue, but it might be worth upgrading to 8.1.8
to see if that just makes it go away.
--
Richard Huxton
Archonet Ltd
