Date: Tue, 13 Jun 2006 16:54:19 -0500
From: "Jim C. Nasby" <jnasby@pervasive.com>
To: Shaun Thomas <sthomas@leapfrogonline.com>
Cc: pgsql-performance@postgresql.org, Tom Lane <tgl@sss.pgh.pa.us>
Subject: Re: Confirmation of bad query plan generated by 7.4
Message-ID: <20060613215418.GI34196@pervasive.com>
References: <9119.1150222168@sss.pgh.pa.us>
	<448EDFC4.8F27.00A9.0@leapfrogonline.com>
	<20060613211347.GB34196@pervasive.com>
	<448EE95D.8F27.00A9.0@leapfrogonline.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <448EE95D.8F27.00A9.0@leapfrogonline.com>
User-Agent: Mutt/1.5.11

On Tue, Jun 13, 2006 at 04:35:41PM -0500, Shaun Thomas wrote:
> >>> On 6/13/2006 at 4:13 PM, "Jim C. Nasby" <jnasby@pervasive.com>
> wrote:
> 
> 
> > Is there some compelling reason to stick with 7.4? In my experience
> > you'll see around double (+100%) the performance going to 8.1...
> 
> Not really.  We *really* want to upgrade, but we're in the middle of
> buying the new machine right now.  There's also the issue of migrating
> 37GB of data which I don't look forward to, considering we'll need to
> set up a slony replication for the entire thing to avoid the hours 
> of downtime necessary for a full dump/restore.
 
As long as the master isn't very heavily loaded it shouldn't be that big
a deal to do so...

> > What's your stats target set to for that table?
> 
> Not sure what you mean by that.  It's just that this table has 27M
> rows
> extending over 4 years, and I'm not quite sure how to hint to that.
> An index scan for a few days would be a tiny fraction of the entire
> table, so PG being insistent on the sequence scans was confusing the
> hell
> out of me.

What's the output of
SELECT attname, attstattarget
    FROM pg_attribute
    WHERE attrelid='table_name'::regclass AND attnum >= 0;
and
SHOW default_statistics_target;

?
-- 
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