Corrupted DB? could not open file pg_clog/####

Looking at archives seem to indicate missing pg_clog files is some form
of row or page corruption.

In an old thread from back in 2003 Tom Lane recommended
(http://tinyurl.com/jushf):

>>If you want to try to narrow down where the corruption is, you can
>>experiment with commands like
>>select ctid,* from big_table offset N limit 1;

Is that still a valid suggestion?
How do I know the possible maximun value for offset to try for each table?

If I have logs turned on.. at which level will the eror show? I am only
aware of the problem, because an application connected to postgrseql had the
errors in it's logs, but not seeing anything in the postgresql logs
themselves.

Just tried a pg_dump and got the
could not open file "pg_clog/0000"
error.

The file pg_clog/0000 is missing.
Looking at another thread (http://tinyurl.com/feyye) I see that the file can
be created as 256K worth of zeroes. If I do this.. will operations resume
normally? Is there a way to tell if any data was lost?