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From: Tomas Vondra <[email protected]>
To: David Rowley <[email protected]>
To: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
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Cc: [email protected]
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Subject: Re: Parallel Bitmap Heap Scan reports per-worker stats in EXPLAIN ANALYZE
Date: Fri, 3 Apr 2026 21:20:16 +0200
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAApHDvo+mqzBNW3YX2EnK0P+Y=f=+2VpWXdHF477susd-bk+-A@mail.gmail.com>
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Hi,

I'm working on adding information about prefetching for scans [1], which
includes BitmapHeapScan. I realized the instrumentation added by this
thread may not be quite right, resulting in missing instrumentation for
non-parallel-aware scans in a parallel query.

A better description / explanation of the issue is posted here [2]. I've
posted a proposed fix in the following message [3], in a patch:

  v8-0002-Show-Bitmap-Heap-Scan-stats-for-non-parallel-awar.patch

I wonder if someone from this thread could review my analysis, and
confirm this is not intentional. I don't see it discussed in the thread,
so I assume no one noticed this behavior. I'd also appreciate a review
of the proposed fix, or suggestions for alternative fixes.

regards


[1]
https://www.postgresql.org/message-id/a177a6dd-240b-455a-8f25-aca0b1c08c6e%40vondra.me

[2]
https://www.postgresql.org/message-id/3bdbc70d-ad44-494a-8aab-868b5066fe8b%40vondra.me

[3]
https://www.postgresql.org/message-id/fce326bb-1210-4d48-8c97-bb3bca396eba%40vondra.me

-- 
Tomas Vondra






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