Re: ANALYZE locks pg_listener in EXCLUSIVE for long time?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Philip Warner <pjw(at)rhyme(dot)com(dot)au>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: ANALYZE locks pg_listener in EXCLUSIVE for long time?
Date: 2004-05-03 04:54:22
Message-ID: 5028.1083560062@sss.pgh.pa.us
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Philip Warner <pjw(at)rhyme(dot)com(dot)au> writes:
> At 02:33 PM 3/05/2004, Tom Lane wrote:
>> Could you dig a little deeper and see where the problem really is?

> I thought I had 8-(.

> The result of a 'select * from pg_locks where not granted' was a bunch of
> locks on the pg_listener relation, and no others. Only one process had a
> lock on that relation, and it was an ANALYZE command.

I don't believe any of this. In the first place, if you're not using
LISTEN/NOTIFY then there's no reason for any backend to try to take out
an AccessExclusive lock on pg_listener (which is the only kind that would
be blocked by ANALYZE's measly AccessShareLock). In the second place,
an ANALYZE on a zero-page relation cannot conceivably take half an hour,
unless it's in turn being blocked by something else.

Please dig deeper.

regards, tom lane

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