Re: VACUUM FULL for performance

In response to Szymon Guz <mabewlun@gmail.com>:

> 2010/10/7 Devrim GÜNDÜZ <devrim@gunduz.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/