I have had similar troubles, related to oid overflow. I had to modify pg_dump 
to properly cast queries that contain oids. This is against 7.1.3 source. The 
patch was hacked quickly, in order to get a corrupted database reloaded, and 
this while I was traveling in another country... so it is far from perfect but 
saved my database(s). It also fixes other oid-related troubles of pg_dump.

See attached file.

Daniel

>>>Brian Fujito said:
 > Thanks for your input--
 > 
 > I've tried both ways:
 > 
 > createlang/droplang from the command line as user postgres
 > 
 > and:
 > 
 > CREATE FUNCTION plpgsql_call_handler () RETURNS OPAQUE AS
 >         '/usr/lib/pgsql/plpgsql.so' LANGUAGE 'C';
 > 
 > CREATE TRUSTED PROCEDURAL LANGUAGE 'plpgsql'
 >         HANDLER plpgsql_call_handler
 >           LANCOMPILER 'PL/pgSQL';
 >        
 > I'm using pg_dump (not pg_dumpall) on the specific database on which
 > I created the language.
 > 
 > I realize 7.0.3 is ancient (same with 7.1)... I just don't have the
 > time to deal with an upgrade quite yet.  Soon enough :)  In the mean
 > time, a stop-gap solution would definitely be appreciated.
 > 
 > Thank you,
 > Brian
 > 
 > 
 > On Mon, 2002-12-09 at 14:28, Tom Lane wrote:
 > > Brian Fujito <brian@lightsource.com> writes:
 > > > I'm running postgres-7.0.3 on RH7.1 using RedHat RPMs.
 > > > I recently added plpgsql as a language to one of my databases, 
 > > > and now when I try to do a pg_dump, I get:
 > > 
 > > > "dumpProcLangs(): handler procedure for language plpgsql not found"
 > > 
 > > > If I drop the language, pg_dump works fine, but if I add it back (and
 > > > even if I restart postgres), I get the same error.
 > > 
 > > What exactly are you doing to drop and re-add the language?  I should
 > > think CREATE LANGUAGE would fail if the handler proc isn't there.
 > > 
 > > (Also, are you doing pg_dump or pg_dumpall?  If the latter, maybe the
 > > failure is occurring in a different database than the one you are
 > > changing.)
 > > 
 > > But having said that, 7.0.3 is ancient history ... you really are
 > > overdue for an upgrade.  With my Red Hat fedora on, I'd say the same
 > > about your choice of OS version too.
 > > 
 > > 			regards, tom lane
 > 
 > 
 > 
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Tue, 10 Dec 2002 09:06:17 +0200
Daniel Kalchev <daniel@digsys.bg>
Re: "dumpProcLangs(): handler procedure for language 