PG Bug reporting form <noreply@postgresql.org> writes:
> Like I said I can't have a database with another db_name and
> username
Sure you can. The bootstrap superuser account's name is set by
initdb [1]. It's true that you can't change the initial set of
database names (postgres, template0, template1), but you can
create more databases within the installation [2].
If you're really stubborn you can delete or rename the postgres
database, but you might regret it. A lot of client tools assume
that as the default database-to-connect-to. I don't recommend
deleting or renaming template0 or template1 under any
circumstances [3].
regards, tom lane
[1] https://www.postgresql.org/docs/current/app-initdb.html
[2] https://www.postgresql.org/docs/current/manage-ag-createdb.html
[3] https://www.postgresql.org/docs/current/manage-ag-templatedbs.html