How to control memory usage of postgresql - Mailing list pgsql-novice

Hi,
I have a postgreSQL database running and sometime ago there was a small
problem, some query running inside the server was onsuming too much
memory, so the server (a DEBIAN LINUX) became out of memory.
 To solve that, the server must drop all queries that start using a lot
of memory, before the server get out of memory again, how can I do that?

Thanks in advance,
Andre.