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base repository: postgresql-cfbot/postgresql
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  • 2 commits
  • 6 files changed
  • 2 contributors

Commits on Aug 10, 2025

  1. Add pg_get_multixact_stats() SQL function for monitoring multixact usage 

    This patch adds pg_get_multixact_stats(), a SQL-callable function that returns
multixact statistics to aid in monitoring wraparound risk and vacuum behavior.
It reports:

multixacts: the number of multixact IDs created since the oldest one still needed
members: the number of multixact member entries that currently exist
oldest_multixact: the oldest multixact ID still needed by any database

The function modifies ReadMultiXactCounts() to expose the oldestMultiXactId and
returns all three values in a composite record. This allows users to monitor
multixact usage and identify potential wraparound issues, particularly useful
when combined with pg_get_multixact_members() to investigate specific multixacts.

Usage:
SELECT * FROM pg_get_multixact_stats();

Documentation is added to:
- "Transaction ID and Snapshot Information Functions" section in func.sgml
- "Multixacts and Wraparound" section in maintenance.sgml
  (routine-vacuuming.html#VACUUM-FOR-MULTIXACT-WRAPAROUND)

Isolation tests are added to verify:
- Initial state with zero multixacts
- multixact creation with overlapping shared locks
- Correct counting of multixacts and members
- Proper tracking of oldest multixact ID

Author: Naga Appani <[email protected]>
Reviewed-by: Ashutosh Bapat <[email protected]>
Reviewed-by: Michael Paquier <[email protected]>
Discussion: https://www.postgresql.org/message-id/flat/CAM2BeoX%2BRasKfG6W8w4qYZZz4BnhyEQMA_y5cEDnKEY_z8o9Czg%40mail.gmail.com
    Naga Appani authored and Commitfest Bot committed Aug 10, 2025
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  2. [CF 5811] v3 - Expose internal MultiXact member count function for ef… 

    …ficient monitoring

This branch was automatically generated by a robot using patches from an
email thread registered at:

https://commitfest.postgresql.org/patch/5811

The branch will be overwritten each time a new patch version is posted to
the thread, and also periodically to check for bitrot caused by changes
on the master branch.

Patch(es): https://www.postgresql.org/message-id/CA+QeY+D_npapLjsu0UZ-pgRGLwqx0GjAmRL_a+R9UOB7jgY=_Q@mail.gmail.com
Author(s): Naga Appani
    Commitfest Bot committed Aug 10, 2025
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