Old pg_clog files

Hi,

v8.4.17

http://www.postgresql-archive.org/pg-clog-questions-td2080911.html

According to this old thread,  doing a VACUUM on every table in the 
postgres, template1 and TAPd databases should remove old pg_clog files.

postgres=# SELECT datname, age(datfrozenxid) FROM pg_database;
   datname  |    age
-----------+-----------
template1 |   9951058
template0 |   9814761
postgres  | 163406258
TAPd      | 179543997
(4 rows)


However, while about 40 of them have been deleted, 183 still exist. What did 
I do wrong?

Thanks

-- 
World Peace Through Nuclear Pacification