Re: Trouble using plpgsql after 8.0 install

Aaron Craig <mercutio(at)pobox(dot)com> writes:
> I get this result:
> ERROR: could not load library "/usr/lib/pgsql/plpgsql.so":
> /usr/lib/pgsql/plpgsql.so: undefined symbol: PG_exception_stack

This sounds like you are trying to load a newer plpgsql.so into an older
backend. In the context of the update process you describe, I can't
help wondering if you remembered to stop the old postmaster and start a
new one. You could still be talking to the running old postmaster
despite having deleted all its executable files from underneath it.

(Recent RPMs include an auto postmaster stop when uninstalling the server
package, but that wasn't always there.)

Note that another important step missing from your description was
dumping the old database so you could load it into the new postmaster.
It'd be a good idea to run pg_dumpall before trying to shut down the
old postmaster --- I'm not 100% sure that will work, but if it does,
it will save you having to reinstall the old RPMs in order to dump your
data.

regards, tom lane