Re: Incorrect result of bitmap heap scan.

From: Andres Freund <andres(at)anarazel(dot)de>
To: "Core Studios Inc(dot)" <corestudiosinc(at)gmail(dot)com>
Cc: Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com>, Peter Geoghegan <pg(at)bowt(dot)ie>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, 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>
Subject: Re: Incorrect result of bitmap heap scan.
Date: 2025-09-16 15:25:14
Message-ID: 3pv2uqpgchv4x23q6h6r7rwsh5kkybnq4a3vrrhgko3pmoeabh@ruh77u5xms4w
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Hi,

On 2025-09-16 15:55:49 +0300, Core Studios Inc. wrote:
> Following up to correct my previous email: the query plan did not really
> change - we see Bitmap Heap Scans even before the upgrade. Therefore, the
> query plan doesn't seem to have changed after the upgrade.
>
> However after the upgrade it seems that those queries are doing more disk IO
> (increased index_blocks_read in that table).

Without the query + plan I can't judge whether the query could even have
benefited from the, fairly narrow, optimization...

Greetings,

Andres

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