Re: BUG #4120: ERROR: cache lookup failed for function 0

"Pedro Gimeno" <pgsql-002(at)personal(dot)formauri(dot)es> writes:
> I have an application running under Windows (tried both with XP and 2000)
> which when run, gets the server to a point in which every comparison of
> varchar < varchar gives the above error:

> postgres=# select ''::varchar < ''::varchar;
> ERROR: cache lookup failed for function 0

Interesting. The symptom sounds vaguely familiar, though I can't find
any relevant-looking CVS log entries right now. I'd suggest updating to
8.2.7 before you spend much time looking at this. If it's still there
in 8.2.7, probably the most productive thing is to work on extracting
a reproducible test case to send in. I'd suggest approaching that by
turning on log_statement to get a trace of everything the application
does up to the failure, and then (assuming you can duplicate the failure
by running that script) trimming it down to eliminate any private
information.

regards, tom lane