From: Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
To: pgsql-performance@postgresql.org
Subject: Re: Autovacuum Issue
Date: Fri, 02 Dec 2011 11:35:20 +1300
Message-ID: <4ED80128.80600@catalyst.net.nz> (raw)
In-Reply-To: <CA+TgmobPwvrHXgBYHPcY9jFpaTumGaMHi-vMTm5hFLVxircQGw@mail.gmail.com>
References: <CA+-36iH+UgRP+hhZSOScUtMGTutFtepDNY-E7C_tvubWhbfcjw@mail.gmail.com>
<CA+TgmobPwvrHXgBYHPcY9jFpaTumGaMHi-vMTm5hFLVxircQGw@mail.gmail.com>
On 02/12/11 07:18, Robert Haas wrote:
>
> And also please share your views on my decision about disable autovacuum for
> my application. I am planning to run vacuum command daily on that small
> table which has frequent updates.
> Sounds like a bad plan.
>
If the table has frequent updates vacuuming once a day will not control
space bloat from dead rows... so your small table's storage will become
a very large (even though there are only a few undeleted rows), and
performance will become terrible.
I would suggest tuning autovacuum to wakeup more frequently (c.f
autovacuum_naptime parameter), so your small table stays small.
Also you didn't mention what version of Postgres you are running. In 8.4
and later vacuum (hence autovacuum) is much smarter about finding dead
rows to clean up, and should have less impact. You can also control the
load autovacuum puts on your system (c.f autovacuum_vacuum_cost_delay
parameter).
regards
Mark
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To: pgsql-performance@postgresql.org
Cc: mark.kirkwood@catalyst.net.nz
Subject: Re: Autovacuum Issue
In-Reply-To: <4ED80128.80600@catalyst.net.nz>
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