Re: Hash join on int takes 8..114 seconds

From: "Andrus" <kobruleht2(at)hot(dot)ee>
To: "Richard Huxton" <dev(at)archonet(dot)com>, "PFC" <lists(at)peufeu(dot)com>
Cc: <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Hash join on int takes 8..114 seconds
Date: 2008-11-21 19:10:21
Message-ID: 8D7F64CF7F614E13AC554D6CF86F39B2@andrusnotebook
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>> How to vacuum full pg_shdepend automatically so that other users can
>> work at same time ?
>
> Your table is horribly bloated.
> You must use VACUUM FULL + REINDEX (as superuser) on it, however
> unfortunately, it is blocking.
> Therefore, you should wait for sunday night to do this, when noone will
> notice.

Shops are closed late night for a short time, including sunday night.
This time may be shorter than time required to complete VACUUM command.

I discovered vacuum_cost_delay=2000 option. Will this remove blocking issue
and allow vacuum full to work ?

> Meanwhile, you can always VACUUM it (as superuser) and REINDEX it.

I expect that autovacuum does this automatically.

> And while you're at it, VACUUM FULL + reindex the entire database.
> To avoid such annoyances in the future, you should ensure that autovacuum
> runs properly ; you should investigate this. If you use a cron'ed VACUUM
> that does not run as superuser, then it will not be able to VACUUM the
> system catalogs, and the problem will come back.

autovacuum is turned on in postgresql.conf file
log file shows a lot of messages every day that database is vacuumed.
I assume that it is running as user postgres.

I do'nt understand how autovacuum can avoid this: it does not perform vacuum
full so pg_shdepend ja my tables become
bloated again and again.

Andrus.

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