Horton

Avoid division-by-zero when calculating autovacuum MXID score.

Nathan Bossart <nathan@postgresql.org>

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Commit: 1f2297b548794a0fec502a9fc70c9970d96b09c4
Author: Nathan Bossart <nathan@postgresql.org>
Date: 2026-06-18T15:18:25Z
Releases: 19 (unreleased) 
Avoid division-by-zero when calculating autovacuum MXID score.

In some cases, effective_multixact_freeze_max_age can be 0, which
presents a division-by-zero hazard for the multixact ID age score
calculation.  To fix, bump it to 1 in that case so that we use the
multixact ID age as the score.  While at it, also document that
this component score scales due to high multixact member space
usage.

Reported-by: Masahiko Sawada <sawada.mshk@gmail.com>
Author: Sami Imseih <samimseih@gmail.com>
Reviewed-by: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Discussion: https://postgr.es/m/CAD21AoC6nKeYAjTvJ9dmBea03GZK9222h_O%3DONmcVuxfyO88Bg%40mail.gmail.com

Files

PathChange+/−
doc/src/sgml/maintenance.sgml modified +4 −2
src/backend/postmaster/autovacuum.c modified +8 −3

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