Good morning, long time reader, first time writer. Where I currently work my colleagues used libc collations before I arrived. While using libc collations, they stumbled upon the collation update problem after SLES updates (15.4 to 15.5) (collation version difference for database and operating system) (paraphrased, don't have the english message at the hand). For an easy solution I suggested to switch to ICU collations. While documenting the problem for older systems I realized that I did not know enough about the problem to document why ICU collations would solve this problem. After reading https://www.postgresql.org/docs/17/collation.html this is how I understand it: When initdb creates a cluster the OS available collations are copied to the database as database objects, listable using select * from pg_collation; Now, an OS collation update as part of the OS update will change the collations available on the OS level, but not the collations that the database uses. Is my understanding correct then in that this way the database collations never change, unless a manual intervention reinitialises the collations and reindexes the database (or appropriate indexes)? How does that process compare to other RDBMS? Are regular collation updates deemed unnecessary for long running database installations? Or do you people have maintenance workflows that incorporate regular collation updates to the databases? Thanks, Thomas
