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Re: 8.3devel slower than 8.2 under read-only load

From: Simon Riggs <simon(at)2ndquadrant(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Guillaume Smet <guillaume(dot)smet(at)gmail(dot)com>, Gregory Stark <stark(at)enterprisedb(dot)com>, "Jonah H(dot) Harris" <jonah(dot)harris(at)gmail(dot)com>, Greg Smith <gsmith(at)gregsmith(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: 8.3devel slower than 8.2 under read-only load
Date: 2007-11-26 16:58:57
Message-ID: 1196096337.4246.778.camel@ebony.site (view raw or flat)
Thread:
Lists: pgsql-hackers
On Mon, 2007-11-26 at 09:55 -0500, Tom Lane wrote:
> Simon Riggs <simon(at)2ndquadrant(dot)com> writes:
> > But I think there must be an action that we can take for 8.3 and that
> > much runtime should not be given away easily. ISTM that we can win back
> > the losses Guillaume has identified, plus gain a little more even.
> 
> Perhaps some sanity could be restored to this discussion by pointing out
> that the 2007-01-01 code *also* clocks in at 37% spent in
> oper_select_candidate.  IOW it's been like this for a very long time.
> I'm not interested in destabilizing 8.3 with panicky last-minute patches.

I think this is worth taking action on, IMHO.

I've written up my suggestion as a 5 line patch, with measured
performance improvement of about 40% for the varchar case. 

It isn't a great long term fix, but I don't want to delay 8.3 either
with the full fix.

-- 
  Simon Riggs
  2ndQuadrant  http://www.2ndQuadrant.com


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