Horton

Re: Doc fix of aggressive vacuum threshold for multixact members storage

Sami Imseih <samimseih@gmail.com>

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From: Sami Imseih <samimseih@gmail.com>
To: Alex Friedman <alexf01@gmail.com>
Cc: pgsql-hackers@lists.postgresql.org
Date: 2025-02-04T19:23:28Z
Lists: pgsql-hackers

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I confirmed the 20GB value as is described here [1].
8k page can hold 409 member groups and each
member group can hold 4 members, thus
(2^32/(409 *4))*8192 = 20GB.

I also fixed whitespace issues in v3.

This is ready-for-committer In my opinion.

Regards,

Sami

[1] https://github.com/postgres/postgres/blob/HEAD/src/backend/access/transam/multixact.c#L131-L137

Commits

  1. Doc: correct aggressive vacuum threshold for multixact members storage

  2. docs: clarify new aggressive vacuum mode for multi-xacts

  3. Increase threshold for multixact member emergency autovac to 50%.