Dba_tab_privs vs all_tab_privs

Question

If we query all_tab_privs (as user SYSTEM) for a particular SCHEMA we get a different set of privs (just SELECT) than when we query dba_tab_privs (SELECT and INSERT, UPDATE) for the same OWNER.objects...why would that be?

Answer 1

Well they are almost identical, with some difference in underlying query.
DBA_TAB_PRIVS
select ue.name, u.name, o.name, ur.name, tpm.name,
       decode(mod(oa.option$,2), 1, 'YES', 'NO'),
       decode(bitand(oa.option$,2), 2, 'YES', 'NO')
from sys.objauth$ oa, sys.obj$ o, sys.user$ u, sys.user$ ur, sys.user$ ue,
     table_privilege_map tpm
where oa.obj# = o.obj#
  and oa.grantor# = ur.user#
  and oa.grantee# = ue.user#
  and oa.col# is null
  and oa.privilege# = tpm.privilege
  and u.user# = o.owner#ALL_TAB_PRIVS
select ur.name, ue.name, u.name, o.name, tpm.name,
       decode(mod(oa.option$,2), 1, 'YES', 'NO'),
       decode(bitand(oa.option$,2), 2, 'YES', 'NO')
from sys.objauth$ oa, sys.obj$ o, sys.user$ u, sys.user$ ur, sys.user$ ue,
     table_privilege_map tpm
where oa.obj# = o.obj#
  and oa.grantor# = ur.user#
  and oa.grantee# = ue.user#
  and oa.col# is null
  and u.user# = o.owner#
  and oa.privilege# = tpm.privilege
  and (oa.grantor# = userenv('SCHEMAID') or
       oa.grantee# in (select kzsrorol from x$kzsro) or
       o.owner# = userenv('SCHEMAID'))