Re: Incorrect result of bitmap heap scan.

From: Peter Geoghegan <pg(at)bowt(dot)ie>
To: Andres Freund <andres(at)anarazel(dot)de>
Cc: Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com>, Andrew Dunstan <andrew(at)dunslane(dot)net>, Melanie Plageman <melanieplageman(at)gmail(dot)com>, Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, Konstantin Knizhnik <knizhnik(at)garret(dot)ru>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, Alexander Kuzmenkov <akuzmenkov(at)timescale(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Heikki Linnakangas <hlinnaka(at)iki(dot)fi>
Subject: Re: Incorrect result of bitmap heap scan.
Date: 2024-12-02 20:59:36
Message-ID: CAH2-WznOtpQ=Pb7cO2ppigR+UDpTTuRUmiND042mwM1P3pdLNw@mail.gmail.com
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On Mon, Dec 2, 2024 at 3:56 PM Peter Geoghegan <pg(at)bowt(dot)ie> wrote:
> I took what you wrote, and repurposed it to prove my old theory about
> GiST index-only scans being broken due to the lack of an appropriate
> interlock against concurrent TID recycling. See the attached patch.

BTW, if you change the test case to use the default B-Tree index AM
(by removing "USING GIST"), you'll see that VACUUM blocks on acquiring
a cleanup lock (and so the test just times out). The problem is that
GiST VACUUM just doesn't care about cleanup locks/TID recycling safety
-- though clearly it should.

--
Peter Geoghegan

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