SQL query to find top 5 users having more rows/data in table

Question

Dear experts,
OS = HP-UX
Database = Oracle 9.2.0.8
AC users = 600
Ex:-
select * from all_users where username like 'AC%';
AC_1
AC_2
AC_3
AC_4
AC_5
AC_6
AC_.
AC_.
AC_.
AC_600
Each AC user having same tables INCOMING, OUTGOING
Now i need to find top 5 users having more rows/data in INCOMING , OUTGOING tables. I tried this:
SQL>conn AC_1/pwd
select 'select count(*) from '||table_name||';' from user_tables;
But i get max counts info only for this AC_1 user , however, i need top 5 users having more rows/max counts query.
Thank you,

Answer 1

source : oracle forums
May be , this one.. not tested though.
Before doing this you need to have select_catalog_role
WITH tmp
     AS (SELECT owner,
                table_name,
                TO_NUMBER (
                   EXTRACTVALUE (
                      xmltype (
                         DBMS_XMLGEN.getxml (
                            'select /*+ PARALLEL*/ count(*) c from '
                            || table_name)),
                      '/ROWSET/ROW/C'))
                   Cnt
           FROM dba_tables
          WHERE 1 = 1 AND table_name IN ('INCOMING', 'OUTGOING')),
     tmp1
     AS (SELECT a.*,
                MAX (cnt)
                   OVER (PARTITION BY a.table_name ORDER BY a.cnt DESC)
                   maxcnt
           FROM tmp a)
SELECT DISTINCT a.*
  FROM tmp a, tmp1 b
WHERE a.cnt = b.maxcnt AND a.table_name = b.table_name;