Re: GiST indexes and concurrency (tsearch2)

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