SQL to list Databases, Schemas, Users and  Roles in Greenplum

-- list databases

select datname,datacl from pg_database;

-- List Schemas

select nspname from pg_catalog.pg_namespace;

-- List User Roles

select usename as username from pg_user;

 -- List Group Roles

select distinct rolname as group_role from pg_roles join pg_auth_members on (pg_roles.oid=pg_auth_members.roleid);