Вот что  я получил  используя предложенную в предыдуш\щем посте команду(psql - самая крутая из консольных утилитт- оракловый sqlpus  нервно курит бамбук isql от sybase, firebird - фтопку - там рулят  толстопопые тормозные GUI)
=# \dg
********* QUERY **********
SELECT g.groname AS "Group name",
  g.grosysid AS "Group ID"
FROM pg_catalog.pg_group g
ORDER BY  1 ;
**************************

    List of groups
 Group name | Group ID 
------------+----------
 ahtungi    |       103 
 dolboebi   |       104 
 kozli      |       101 
 pidorasi   |       100 
 vomuchki   |       102 
( 5  rows)

=# \du
********* QUERY **********
SELECT u.usename AS "User name",
  u.usesysid AS "User ID",
  CASE WHEN u.usesuper AND u.usecreatedb THEN CAST('superuser, create database' AS pg_catalog.text)
       WHEN u.usesuper THEN CAST('superuser' AS pg_catalog.text)
       WHEN u.usecreatedb THEN CAST('create database' AS pg_catalog.text)
       ELSE CAST('' AS pg_catalog.text)
  END AS "Attributes",
  ARRAY(SELECT g.groname FROM pg_catalog.pg_group g WHERE u.usesysid = ANY(g.grolist)) as "Groups"
FROM pg_catalog.pg_user u
ORDER BY  1 ;
**************************

                             List of users
 User name | User ID |         Attributes         |       Groups       
-----------+---------+----------------------------+--------------------
 p1        |      101  |                            | {ahtungi,dolboebi}
 p2        |      102  |                            | {ahtungi,dolboebi}
 p3        |      103  |                            | {kozli}
 p4        |      104  |                            | {pidorasi}
 p5        |      105  |                            | {pidorasi}
 p6        |      106  |                            | 
 p7        |      107  |                            | 
 p8        |      108  |                            | 
 postgres  |        1  | superuser, create database | 
 
=# SELECT u.usename AS "User name",
  u.usesysid AS "User ID",
  ARRAY(SELECT g.groname FROM pg_catalog.pg_group g WHERE u.usesysid = ANY(g.grolist)) as "Groups"
FROM pg_catalog.pg_user u
 where 'dolboebi' in (SELECT g.groname FROM pg_catalog.pg_group g WHERE u.usesysid = ANY(g.grolist)) 
ORDER BY  1 ;
 User name | User ID |       Groups       
-----------+---------+--------------------
 p1        |      101  | {ahtungi,dolboebi}
 p2        |      102  | {ahtungi,dolboebi}
( 2  rows)

=# SELECT u.usename AS "User name",
  u.usesysid AS "User ID",
  ARRAY(SELECT g.groname FROM pg_catalog.pg_group g WHERE u.usesysid = ANY(g.grolist)) as "Groups"
FROM pg_catalog.pg_user u
 where 'pidorasi' in (SELECT g.groname FROM pg_catalog.pg_group g WHERE u.usesysid = ANY(g.grolist)) 
ORDER BY  1 ;

 User name | User ID |   Groups   
-----------+---------+------------
 p4        |      104  | {pidorasi}
 p5        |      105  | {pidorasi}
( 2  rows)
[/fixed]