[HACKERS] subselect bug?

[Tatsuo Ishii]

While below is ok:

select * from table_a a
    where (select data_a from table_a where id = a.id) >
          (select data_b from table_a where id = a.id);

but this fails:

select * from table_a a
    where ((select data_a from table_a where id = a.id) >
           (select data_b from table_a where id = a.id));

ERROR:  parser: parse error at or near ">"

Does anybody know why?
--
Tatsuo Ishii