From: Tom Lane <tgl@sss.pgh.pa.us>
To: Nikhil Shetty <nikhil.dba04@gmail.com>
cc: Pgsql-admin <pgsql-admin@lists.postgresql.org>
Subject: Re: Modify Bootstrap user ID
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Comments: In-reply-to Nikhil Shetty <nikhil.dba04@gmail.com>
	message dated "Wed, 21 Feb 2024 23:47:30 +0530"
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Date: Wed, 21 Feb 2024 13:39:18 -0500
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Nikhil Shetty <nikhil.dba04@gmail.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