> One coincidence is that we started seeing the first symptoms of this
> around the same time as libicu was updated with a security patch.
> However, postgres hasn’t been restarted and doesn’t reference the
> new version in its process maps. Plus state groups are integers
> anyway. We also use the C locale, not ICU.
Sounds as if you are hit by locale changes:
https://wiki.postgresql.org/wiki/Locale_data_changes
I think you will need to upgrade to prevent future problems like that:
Postgres 15 introduced some mechanisms to track and validate version discrepancies after an OS update.
Postgres 17 added a "built-in" collation provider which is independent of glibc
