Postmaster hogs CPU

When I run an query (that I have identified as expensive, and non-critical), I
would like to be able to take its priority down a few notches to allow the
standard every-day tasks of the DB to run unhindered. As it stands, postmasters
elbow each other out for processor time, and it seems like one expensive query
can bring other DB functions to a crawl.

Hardware : Dual P4 Xeon 2.8GHz; 1 GB RAM; ULTRA320 RAID 10 with an ext3
filesystem
PostgreSQL 7.4.2

What can be done to allow for smarter preemption? Could I do anything at the OS
level to throttle that particular postmaster's process? I'm running (IMO) a
balanced config, but there's always room for improvement. Its that oddball
query that comes around once every so often that causes the problem.

CG




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