Problem with complex query

Hello!

Query:

SELECT DISTINCT p.subsec_id  FROM central cn, shops sh, districts d, positions p     WHERE cn.shop_id = sh.shop_id AND
sh.distr_id= d.distr_id     AND   d.city_id = %d AND cn.pos_id = p.pos_id     AND   cn.date_i >= current_date - '7
days'::timespan

While running postgres slowly eats all swap space (30 Meg) and aborts:

pqReadData() -- backend closed the channel unexpectedly.       This probably means the backend terminated abnormally
beforeor
 
while processing the request.
  Is it I just have not enough memory or bug?

Oleg.
----    Oleg Broytmann     http://members.xoom.com/phd2/     phd2@earthling.net          Programmers don't die, they
justGOSUB without RETURN.