On Wed, 2022-12-21 at 15:24 +0100, Karsten Hilbert wrote: > I managed to drop the "special" collations default, C, and > POSIX with OIDs 100, 950, 951. > > Is there a way to recreate them (short of restoring a backup) > ? Naive attempts with create collation do not seem to work > out. I would definitely go for the backup, but here is how you can create these three rows in PostgreSQL v15: INSERT INTO pg_collation (oid, collname, collnamespace, collowner, collprovider, collisdeterministic, collencoding, collcollate, collctype) VALUES (100, 'default', 11, 10, 'd', TRUE, -1, NULL, NULL), (950, 'C', 11, 10, 'c', TRUE, -1, 'C', 'C'), (951, 'POSIX', 11, 10, 'c', TRUE, -1, 'POSIX', 'POSIX'); Yours, Laurenz Albe