Multithreaded query onto 4 postgresql instances

Here you are my probably uncommon situation.

I have installed 4 different instances of postgresql-9.0.2 on the same
machine, on ports 5433, 5434, 5435, 5436.
On these instances I have splitted a huge database, dividing it per date
(from 1995 to 1998 on 5433, from 1999 to 2002 on 5434 and so on...).
Then I have developed a C function using libpq which creates 4 threads,
each one which query a 1/4 of the db. After that I merge the results in
one single response.

My function works fine, but I need to include it inside a postgresql
instance in order to launch it as a normal SQL query (SELECT myfunc(...);).
Why I have to do something tricky like this is long too explain...

I have read the documentation here
http://www.postgresql.org/docs/9.0/static/xfunc-sql.html#XFUNC-SQL-FUNCTIONS-RETURNING-SET,
but I'm pretty confuse and I don't know if this is the right way to
accomplish my goal.

Have you got any ideas or suggestions?

Thanks a lot!

--
Alessandro Candini

MEEO S.r.l.
Via Saragat 9
I-44122 Ferrara, Italy
Tel: +39 0532 1861501
Fax: +39 0532 1861637
http://www.meeo.it

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