Re: psql: Add role's membership options to the \du+ command

Thank you for all valuable comments. I can now continue working on the
patch.
Here's what I plan to do in the next version.

Changes for \du & \dg commands
* showing distinct roles in the "Member of" column
* explicit order for list of roles
* no changes for extended mode (\du+)

New meta-command \drg
* showing info from pg_auth_members based on a query:

SELECT r.rolname role, m.rolname member,
       pg_catalog.concat_ws(', ',
           CASE WHEN pam.admin_option THEN 'ADMIN' END,
           CASE WHEN pam.inherit_option THEN 'INHERIT' END,
           CASE WHEN pam.set_option THEN 'SET' END
       ) AS options,
       g.rolname grantor
FROM pg_catalog.pg_auth_members pam
     JOIN pg_catalog.pg_roles r ON (pam.roleid = r.oid)
     JOIN pg_catalog.pg_roles m ON (pam.member = m.oid)
     JOIN pg_catalog.pg_roles g ON (pam.grantor = g.oid)
WHERE r.rolname !~ '^pg_'
ORDER BY role, member, grantor;
       role       |      member      |       options |     grantor
------------------+------------------+---------------------+------------------
 regress_du_role0 | regress_du_admin | ADMIN, INHERIT, SET | postgres
 regress_du_role0 | regress_du_role1 | ADMIN, INHERIT, SET |
regress_du_admin
 regress_du_role0 | regress_du_role1 | INHERIT | regress_du_role1
 regress_du_role0 | regress_du_role1 | SET | regress_du_role2
 regress_du_role0 | regress_du_role2 | ADMIN | regress_du_admin
 regress_du_role0 | regress_du_role2 | INHERIT, SET | regress_du_role1
 regress_du_role0 | regress_du_role2 | | regress_du_role2
 regress_du_role1 | regress_du_admin | ADMIN, INHERIT, SET | postgres
 regress_du_role1 | regress_du_role2 | ADMIN, SET | regress_du_admin
 regress_du_role2 | regress_du_admin | ADMIN, INHERIT, SET | postgres
(10 rows)

Notes
* The name of the new command. It's a good name, if not for the history.
There are two commands showing the same information about roles: \du and
\dr.
The addition of \drg may be misinterpreted: if there is \drg, then there
is also \dug.
Maybe it's time to think about deprecating of the \du command and leave
only \dg in the next versions?

* 'empty'. I suggest thinking about forbidding the situation with empty
options.
If we prohibit them, the issue will be resolved automatically.

* The new meta-command will also make sense for versions <16.
The ADMIN OPTION is available in all supported versions.

* The new meta-command will not show all roles. It will only show the
roles included in other roles.
To show all roles you need to add an outer join between pg_roles and
pg_auth_members.
But all columns except "role" will be left blank. Is it worth doing this?

--
Pavel Luzanov
Postgres Professional: https://postgrespro.com