Re: POC: make mxidoff 64 bits
Maxim Orlov <orlovmg@gmail.com>
From: Maxim Orlov <orlovmg@gmail.com>
To: Heikki Linnakangas <hlinnaka@iki.fi>
Cc: wenhui qiu <qiuwenhuifx@gmail.com>,
Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>,
Alexander Korotkov <aekorotkov@gmail.com>, Postgres hackers <pgsql-hackers@lists.postgresql.org>
Date: 2025-11-20T16:30:51Z
Lists: pgsql-hackers
Commits
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the thread's linked commits as JSON, with link sources.
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Fix partial read handling in pg_upgrade's multixact conversion
- ac94ce8194e5 19 (unreleased) landed
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Increase timeout in multixid_conversion upgrade test
- bd43940b02b2 19 (unreleased) landed
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Improve sanity checks on multixid members length
- ecb553ae8211 19 (unreleased) landed
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Clarify comment on multixid offset wraparound check
- 170361d7b869 14.21 landed
- b0b52b7123ae 15.16 landed
- 7d42e2367c6b 16.12 landed
- cd1a887fe9bf 17.8 landed
- 3fbad030a24d 18.2 landed
- 366dcdaf5779 19 (unreleased) landed
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Never store 0 as the nextMXact
- 87a350e1f284 19 (unreleased) landed
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Add runtime checks for bogus multixact offsets
- d4b7bde4183b 19 (unreleased) landed
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Widen MultiXactOffset to 64 bits
- bd8d9c9bdfa0 19 (unreleased) landed
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Move pg_multixact SLRU page format definitions to a separate header
- bb3b1c4f6462 19 (unreleased) landed
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Convert confusing macros in multixact.c to static inline functions
- 0099b9408e8c 17.0 landed
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Index SLRUs by 64-bit integers rather than by 32-bit integers
- 4ed8f0913bfd 17.0 cited
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Cope with possible failure of the oldest MultiXact to exist.
- b6a3444fa635 9.4.4 cited
On Wed, 19 Nov 2025 at 19:20, Heikki Linnakangas <hlinnaka@iki.fi> wrote:
>
> I think those recipes need to be adjusted for 64-bit offsets.
Yes, we need to do it.
Sorry if this is too obvious, but with 32-bit offsets, we get:
SLRU_PAGES_PER_SEGMENT * BLKSZ / sizeof(MXOff) =
32 * 8192 / 4 = 65,536 mxoff per segment.
Now, with 64-bits offsets, we should have half as much.
--
Best regards,
Maxim Orlov.