"Stephen Martin" <stephen@sealteam.demon.co.uk> writes:
> For example I have a postgres id 'www' present within my pg_shadow/pg_user.
> I recently installed a package and inadvertantly created another 'www' user.
> How can I
> 1) Ensure I canot in future create duplicate names?
There should probably be a unique index on pg_shadow's usename field,
and another one on the usesysid field (otherwise there's not a unique
map from sysids to users, which is bad since we use sysids as
referential keys in other tables).
I'm surprised this hasn't been pointed out before :-(
I'm not sure how difficult it would be to do it. Just creating
an index with CREATE INDEX will not work, because pg_shadow is
an installation-wide table and its index must be as well. There's
some routine somewhere in the backend that would have to be taught
about the index.
regards, tom lane
