Horton

Re: Incorrect result of bitmap heap scan.

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Matthias van de Meent <boekewurm+postgres@gmail.com>
Cc: vignesh C <vignesh21@gmail.com>, Peter Geoghegan <pg@bowt.ie>, Tom Lane <tgl@sss.pgh.pa.us>, Andrew Dunstan <andrew@dunslane.net>, Melanie Plageman <melanieplageman@gmail.com>, Thomas Munro <thomas.munro@gmail.com>, Konstantin Knizhnik <knizhnik@garret.ru>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Alexander Kuzmenkov <akuzmenkov@timescale.com>
Date: 2025-03-17T17:18:55Z
Lists: pgsql-hackers 
Hi,

On 2025-03-17 16:17:03 +0100, Matthias van de Meent wrote:
> As I understand it, Andres agrees that the feature is unsalvageable in
> backbranches ("don't think there's a realistic way to fix it"). Andres
> then continues to elaborate that even if the feature were salvageable,
> it wouldn't contain much of the current code.

Correct.


> My patch removes the feature altogether in master and disables the
> feature in the backbranches in the patches that were built against the
> backbranches, which seems to match Andres' comments.

Agreed.


> @vignesh, could you elaborate on what about Andres' comments I need to
> address in my patch?

I don't think there are any...

Greetings,

Andres Freund

Commits

  1. Add test for HeapBitmapScan's broken skip_fetch optimization

  2. Remove HeapBitmapScan's skip_fetch optimization

  3. Allow bitmap scans to operate as index-only scans when possible.