Re: Log messages regarding automatic vacuum and exclusive locks

On Tue, Apr 23, 2013 at 8:50 AM, <jonesd(at)xmission(dot)com> wrote:
> Good morning. I'm seeing several of the following log messages each morning
> (for example, there were five this morning, spaced approximately one minute
> apart, with the closest interval between messages being 44 seconds).
> They're occurring during a daily cycle of deleting all rows from a table and
> then repopulating it from another database; the first message came

If all the rows are deleted from the table every time to repopulate it
later, I would suggest using TRUNCATE table_name; instead DELETE FROM
table_name. TRUNCATE does not left any free space in the table so
autovacuum will have nothing to do with it.

> LOG: automatic vacuum of table "x.y.z": could not (re)acquire exclusive
> lock for truncate scan

Hence you will not get this messages and BTW it will be faster.

>
> I'm using default settings for autovacuum, with server version 9.2.4.
>
> Some other smaller tables produce the same messages during the same process,
> but apparently less frequently.
>
> Any thoughts on the cause? Chapters 18 and 23 of the documentation provided
> some hints, but nothing conclusive.
>
>
> Thanks in advance,
>
> Dominic Jones
>
>
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Kind regards,
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Database and Software Consultant

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