Horton

Re: POC: make mxidoff 64 bits

Maxim Orlov <orlovmg@gmail.com>

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From: Maxim Orlov <orlovmg@gmail.com>
To: Heikki Linnakangas <hlinnaka@iki.fi>
Cc: Alexander Korotkov <aekorotkov@gmail.com>, wenhui qiu <qiuwenhuifx@gmail.com>, Postgres hackers <pgsql-hackers@lists.postgresql.org>
Date: 2024-10-23T15:55:06Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Fix partial read handling in pg_upgrade's multixact conversion

  2. Increase timeout in multixid_conversion upgrade test

  3. Improve sanity checks on multixid members length

  4. Clarify comment on multixid offset wraparound check

  5. Never store 0 as the nextMXact

  6. Add runtime checks for bogus multixact offsets

  7. Widen MultiXactOffset to 64 bits

  8. Move pg_multixact SLRU page format definitions to a separate header

  9. Convert confusing macros in multixact.c to static inline functions

  10. Index SLRUs by 64-bit integers rather than by 32-bit integers

  11. Cope with possible failure of the oldest MultiXact to exist.

Attachments

After a bit of thought, I've realized that to be conservative here is the
way to go.

We can reuse a maximum of existing logic. I mean, we can remove offset
wraparound "error logic" and reuse "warning logic". But set the threshold
for "warning logic" to a much higher value. For now, I choose 2^32-1. In
other world, legit logic, in my view, here would be to trigger autovacuum
if the number of offsets (i.e. difference nextOffset - oldestOffset)
exceeds 2^32-1. PFA patch set.

-- 
Best regards,
Maxim Orlov.