Steffn <steffn(at)gmx(dot)at> writes:
> Thanks for your reply. Yes, thats also my suspicion. But what library to
> include?
There is no library to include --- you need to be building *your* code
as a library that can be loaded into the Postgres backend, which will
supply the missing function. This is somewhat platform-specific and
frankly I'd suggest using pgxs rather than puzzling it out for yourself.
See
http://www.postgresql.org/docs/8.3/static/xfunc-c.html#XFUNC-C-PGXS
regards, tom lane