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help / color / mirror / Atom feedFrom: David Geier <[email protected]>
To: Melanie Plageman <[email protected]>
To: Tomas Vondra <[email protected]>
Cc: David Rowley <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
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Cc: [email protected]
Subject: Re: Parallel Bitmap Heap Scan reports per-worker stats in EXPLAIN ANALYZE
Date: Thu, 16 Apr 2026 08:49:58 +0200
Message-ID: <[email protected]> (raw)
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Hi Tomas!
On 05.04.2026 20:27, Melanie Plageman wrote:
> On Fri, Apr 3, 2026 at 3:20 PM Tomas Vondra <[email protected]> wrote:
>>
>> 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 haven't spent a lot of time looking through the code and your patch
but I'm wondering why we're not rather missing a
ExecBitmapIndexScanInstrumentEstimate(), rather than calling
ExecBitmapIndexScanEstimate() also in the !parallel_aware case. All
other scans do it this way, so why do it differently for Bitmap Index Scan?
>> 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.
>
> I can't imagine this was intentional.
Agreed.
--
David Geier
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Subject: Re: Parallel Bitmap Heap Scan reports per-worker stats in EXPLAIN ANALYZE
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