From: | Bill Moran <wmoran(at)potentialtech(dot)com> |
---|---|
To: | Szymon Guz <mabewlun(at)gmail(dot)com> |
Cc: | Devrim GÜNDÜZ <devrim(at)gunduz(dot)org>, AI Rumman <rummandba(at)gmail(dot)com>, pgsql-general General <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: VACUUM FULL for performance |
Date: | 2010-10-07 13:39:58 |
Message-ID: | 20101007093958.278f3c73.wmoran@potentialtech.com |
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Lists: | pgsql-general |
In response to Szymon Guz <mabewlun(at)gmail(dot)com>:
> 2010/10/7 Devrim GÜNDÜZ <devrim(at)gunduz(dot)org>
>
> > On Thu, 2010-10-07 at 17:38 +0600, AI Rumman wrote:
> > > MayVACUUM FULL on a table improve perfromance of the system?
> >
> > No, it will make things worse.
>
> That's not true, I'd rather say that it depends. The whole performance is
> not just about the vacuum full.
My experience:
VACUUM FULL is indicated under the following conditions:
* When routine vacuum has failed for a while due to some problem, or
there are indicators that vacuuming was not being done often enough
and that table bloat has gotten out of hand.
* A major, unusual event has occurred that has cause the # of dead rows
in a table to bloat far out of what happens with normal usage.
I also recommend reindexing any table that has been VACUUM FULLed.
As everyone else has mentioned, VACUUM FULL is not a silver bullet, and
is not _guaranteed_ to improve performance. There are also very few
cases where it's a good idea to do it as routine maintenance. However,
it is a tool that is useful at times, and it's worthwhile to understand
how it works.
--
Bill Moran
http://www.potentialtech.com
http://people.collaborativefusion.com/~wmoran/
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