Re: poor performance on 7.1 vs 7.0

From: Kyle <kaf(at)nwlink(dot)com>
To: pgsql-general(at)postgresql(dot)org
Subject: Re: poor performance on 7.1 vs 7.0
Date: 2001-05-08 20:21:42
Message-ID: 15096.21846.147769.743842@ip146.usw5.rb1.bel.nwlink.com
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When I profile the postmaster do the forked backends also show up in
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Tom Lane wrote:
> Kyle <kaf(at)nwlink(dot)com> writes:
> > I'm getting poor performance on 7.1 as compared to 7.0.
>
> Hm. I don't know why 7.1 might be slower for plain SELECTs (the WAL
> changes would certainly not affect that). Could you compile 7.1 for
> profiling ("make clean; make PROFILE=-pg all" in the src/backend
> subdirectory should do it) and send along a gprof table for your
> test run?
>
> > I've got a btree index on the first 16 of the data elements, and
> > explain verifies that the index is used.
>
> Simple explain doesn't prove that the index is being fully used ---
> the display doesn't distinguish how many index columns are actually
> being looked at. EXPLAIN VERBOSE output would resolve that doubt.
>
> regards, tom lane
>

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