Re: EXPLAIN: showing ReadStream / prefetch stats

From: Melanie Plageman <melanieplageman(at)gmail(dot)com>
To: Tomas Vondra <tomas(at)vondra(dot)me>
Cc: Andres Freund <andres(at)anarazel(dot)de>, Lukas Fittl <lukas(at)fittl(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: EXPLAIN: showing ReadStream / prefetch stats
Date: 2026-04-06 20:33:16
Message-ID: CAAKRu_b1R+syKRvKc+wD1H7jX8QUFWcWQw7HtC48XeGdBRuU0w@mail.gmail.com
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On Mon, Apr 6, 2026 at 12:50 PM Melanie Plageman
<melanieplageman(at)gmail(dot)com> wrote:
>
> I cleaned up the first patch in the set that refactors index-only and
> index scan to use this pattern and realized that I wasn't sure what to
> do about the duplication between index-only and index scans for these
> functions.

I changed my mind about the duplication: I think it's fine because
there just aren't that many lines of code. Attached v10 has a
preparatory commit that adds an assert-only check to shm_toc_insert()
to make sure the key hasn't already been inserted. I thought it would
be helpful since many of the magic numbers for parallel executor
communication are spread around.

- Melanie

Attachment Content-Type Size
v10-0001-Assert-no-duplicate-keys-in-shm_toc_insert.patch text/x-patch 1.1 KB
v10-0002-Allocate-separate-DSM-chunk-for-parallel-Index-O.patch text/x-patch 22.9 KB

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