From: "Greg Sabino Mullane" <greg@turnstep.com>
To: pgsql-general@postgresql.org
Cc: bruce@momjian.us
CC: bruce@momjian.us
Subject: Re: Index bloat of 4x
In-Reply-To: <20070117093223.bcdb302e.wmoran@collaborativefusion.com>
Date: Wed, 17 Jan 2007 16:42:20 -0000
Message-ID: <19dcd19103d2e8b6656dac44879e2fcb@biglumber.com>


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> Today I decided to run reindex during a slow period, and was shocked to
> find the database size drop from 165M to 30M.  Keep in mind that the
> 165M is after vacuum full.  So, apparently, there was 135M of index bloat?
> That seems a little excessive to me, especially when the docs claim that
> reindexing is usually not necessary.

For what its worth, I've seen far worse.

> I guess my question is whether or not this is expected.  It's obviously
> not a good thing -- I've noticed that shared buffer usage has dropped
> dramatically as well (from 28,000 to 7000).  I hadn't expected index
> bloat of this magnitude, and I'm concerned about when the database hits
> 2 or 3 G in size and has 12G just in indexes that take hours to rebuild.

Regular reindexing is so inexpensive compared to vacuum, I recommend
adding it in as part of your regular maintenance. At the very least, it's
unlikely to ever be that severe again unless you don't reindex for an
equally long period of time.

Come to think of it, an auto-reindex option might be nice in core someday.
TODO item?

- --
Greg Sabino Mullane greg@turnstep.com
PGP Key: 0x14964AC8 200701171129
http://biglumber.com/x/web?pk=2529DF6AB8F79407E94445B4BC9B906714964AC8
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