From: | Neil Conway <neilc(at)samurai(dot)com> |
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To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Marinos Yannikos <mjy(at)geizhals(dot)at>, Oleg Bartunov <oleg(at)sai(dot)msu(dot)su>, pgsql-performance(at)postgresql(dot)org |
Subject: | Re: GiST indexes and concurrency (tsearch2) |
Date: | 2005-02-10 01:13:03 |
Message-ID: | 1107997983.1286.132.camel@localhost.localdomain |
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Lists: | pgsql-performance |
On Sat, 2005-02-05 at 14:42 -0500, Tom Lane wrote:
> Marinos Yannikos <mjy(at)geizhals(dot)at> writes:
> > Some more things I tried:
>
> You might try the attached patch (which I just applied to HEAD).
> It cuts down the number of acquisitions of the BufMgrLock by merging
> adjacent bufmgr calls during a GIST index search.
I'm not sure it will help much either, but there is more low-hanging
fruit in this area: GiST currently does a ReadBuffer() for each tuple
produced by the index scan, which is grossly inefficient. I recently
applied a patch to change rtree to keep a pin on the scan's current
buffer in between invocations of the index scan API (which is how btree
and hash already work), and it improved performance by about 10%
(according to contrib/rtree_gist's benchmark). I've made similar changes
for GiST, but unfortunately it is part of a larger GiST improvement
patch that I haven't had a chance to commit to 8.1 yet:
http://archives.postgresql.org/pgsql-patches/2004-11/msg00144.php
I'll try and get this cleaned up for application to HEAD next week.
-Neil
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