| From: | Justin Pryzby <pryzby(at)telsasoft(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> |
| Cc: | Mike Schanne <mschanne(at)kns(dot)com>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: autovacuum locking question |
| Date: | 2019-12-06 17:49:34 |
| Message-ID: | 20191206174934.GR2082@telsasoft.com |
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| Thread: | |
| Lists: | pgsql-performance |
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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