Re: Modify Bootstrap user ID

Nikhil Shetty <nikhil(dot)dba04(at)gmail(dot)com> writes:
> We want to upgrade a postgres v13 database to v16. but the bootstrap user
> used to initialise the database for both are different
> Can we update the bootstrap user for v13 ? like assign oid as 10 in
> pg_authid?

Do not try to change role OIDs --- you will certainly miss some
places where the OID appears. You can rename it though.

You might have tried this:

regression=# alter user postgres rename to pgsql;
ERROR: session user cannot be renamed

but it's easy to get around that:

regression=# create user joe superuser;
CREATE ROLE
regression=# \c - joe
You are now connected to database "regression" as user "joe".
regression=# alter user postgres rename to pgsql;
ALTER ROLE
regression=# \c - pgsql
You are now connected to database "regression" as user "pgsql".
regression=# drop user joe;
DROP ROLE

regards, tom lane