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

[Francisco Reyes <lists(at)stringsutils(dot)com>]

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?