From: Justin Pryzby <pryzby@telsasoft.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
To: Jeff Janes <jeff.janes@gmail.com>
Cc: Mike Schanne <mschanne@kns.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: autovacuum locking question
Date: Fri, 6 Dec 2019 11:49:34 -0600
Message-ID: <20191206174934.GR2082@telsasoft.com> (raw)
In-Reply-To: <CAMkU=1wmmOvKGC+_QqHBE=nM=nqPBq=DJrX8Sk3CeQ+krAcEkA@mail.gmail.com> <26221.1575589746@sss.pgh.pa.us>
On Thu, Dec 05, 2019 at 06:49:06PM -0500, Tom Lane wrote:
> The only part that would get canceled in response to somebody taking a
> non-exclusive lock is the last step, which is truncation of unused blocks at
> the end of the table; that requires an exclusive lock.
On Thu, Dec 05, 2019 at 06:55:02PM -0500, Jeff Janes wrote:
> If the vacuum finds a lot of empty pages at the end of the table, it will
> try to truncate them and takes a strong lock to do so.
Should the exclusive lock bit be documented ?
https://www.postgresql.org/docs/12/explicit-locking.html
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To: pgsql-performance@postgresql.org
Cc: pryzby@telsasoft.com, tgl@sss.pgh.pa.us, jeff.janes@gmail.com, mschanne@kns.com
Subject: Re: autovacuum locking question
In-Reply-To: <20191206174934.GR2082@telsasoft.com>
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