duplicate key value violates unique constraint pg_class_relname_nsp_index

[4kimov]

I got the following error in Postgres when starting up 2 instances, both running the same new migration in parallel (one succeeded, one didn't). The migration itself is a simple CREATE TABLE IF NOT EXISTS ... Of course restarting the failed instance was not a problem and the error was not there anymore. This was the error:

Execution Error: error returned from database: duplicate key value violates unique constraint "pg_class_relname_nsp_index"

The docs mention atomic migrations for Postgres, but is it possible that this might not be enough?

Someone else is using pg_advisory_xact_lock here to fix that issue: https://stackoverflow.com/questions/74261789/postgres-create-table-if-not-exists-%E2%87%92-23505

I couldn't find any similar question in issues, has anybody stumbled on this?