From: Jim C. Nasby <jnasby@pervasive.com>
To: pgsql-performance@postgresql.org
Subject: Re: Why so slow?
Date: Thu, 4 May 2006 12:53:59 -0500
Message-ID: <20060504175359.GO97354@pervasive.com> (raw)
In-Reply-To: <20060503112219.GM31328@mathom.us>
References: <200604281043.16083@hal.medialogik.com>
<BAY101-F38A0FADC87E67C062FE5E1ADB00@phx.gbl>
<20060430100346.20f010a9.wmoran@collaborativefusion.com>
<20060502201740.GB97354@pervasive.com>
<20060502192834.6c8e9131.wmoran@collaborativefusion.com>
<20060503112219.GM31328@mathom.us>
On Wed, May 03, 2006 at 07:22:21AM -0400, Michael Stone wrote:
> On Tue, May 02, 2006 at 07:28:34PM -0400, Bill Moran wrote:
> >Reindexing is in a different class than vacuuming.
>
> Kinda, but it is in the same class as vacuum full. If vacuum neglect (or
> dramatic change in usage) has gotten you to the point of 10G of overhead
> on a 2G table you can get a dramatic speedup if you vacuum full, by
> dumping a lot of unused space. But in that case you might have a similar
s/might/will/
> amount of overhead in indices, which isn't going to go away unless you
> reindex. In either case the unused rows will be reused as needed, but if
> you know you aren't going to need the space again anytime soon you might
> need to vacuum full/reindex.
You can also do a CLUSTER on the table, which rewrites both the table
and all the indexes from scratch. But there was some kind of issue with
doing that that was fixed in HEAD, but I don't think it's been
back-ported. I also don't remember exactly what the issue was... :/
--
Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
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To: pgsql-performance@postgresql.org
Cc: jnasby@pervasive.com
Subject: Re: Why so slow?
In-Reply-To: <20060504175359.GO97354@pervasive.com>
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