postgresql query to show the groups of a user

If I create a user in a group, like:

create role user_1 login inherit in role group_1开发者_如何学Python;

later, with which query could I retrieve to which group(s) a user belongs to?

Just to give a copy&pastable solution - On PostgreSQL (tested 8.4 and 9.3) you can do:

select rolname from pg_user
join pg_auth_members on (pg_user.usesysid=pg_auth_members.member)
join pg_roles on (pg_roles.oid=pg_auth_members.roleid)
where
pg_user.usename='USERNAME';

where USERNAME is the name of the login role you are interested in.

From the psql command line:

\dg

or

\du

Check pg_roles, pg_authid and pg_auth_members to get the details about roles.