Re: ANALYZE locks pg_listener in EXCLUSIVE for long time?

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Philip Warner <pjw(at)rhyme(dot)com(dot)au>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: ANALYZE locks pg_listener in EXCLUSIVE for long time?
Date: 2004-05-03 03:13:04
Message-ID: 200405030313.i433D4M13962@candle.pha.pa.us
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Tom Lane wrote:
> Philip Warner <pjw(at)rhyme(dot)com(dot)au> writes:
> > Does this mean that ANALYZE will take an exclusive lock on pg_listener
> > until the ANALYZE finishes? Or is there some other cause?
>
> ANALYZE does not take an exclusive lock on anything. However, the
> async.c functions want AccessExclusiveLock on pg_listener, so they
> quite possibly would get blocked by ANALYZE's not-so-exclusive lock.
>
> Possibly we could reduce the strength of the lock taken by the async.c
> functions ... I haven't thought hard about it. The long-term answer is
> certainly a wholesale rewrite of the listen/notify mechanism.

Gavin was working on it a while ago but I am not sure how far he got.

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