Description

From #10718 :

Perhaps instead of a warning that should be made to abort startup unless a new setting corrup_my_db_silently_on_libc_update: true is set.

We're fine going with this approach to at least help people avoid silent corruption... details tbd.

We should probably also add the commands needed to drop the broken data from a DB to https://matrix-org.github.io/synapse/latest/postgres.html#fixing-incorrect-collate-or-ctype and also add:

We should also probably link to information on how Glibc collation changes can break PostgreSQL. E.g., https://wiki.postgresql.org/wiki/Locale_data_changes

Steps to reproduce

• have DB use wrong locale
• update libc with locale change
• notice corrupt DB

Version information

• Version: seen e.g. on 1.41.0, but bug exists before and after

• Install method: any

• Platform: Linux glibc