Cost based SELECT/UPDATE

Hi, ppl

Is there any way to do SELECTs with different priorities?

Once a month I need to do some complex reports on table with over 7
billion rows, which implies several nested SELECTS and grouping (query
runs over 20 minutes on P4/2.4GHz). Concurrently, there are over 50
processes updating tables in the same database, including table being
SELECTed to do monthly report. The issue is that response time for
these 50 processes is very important unlike for report generation, and
time spent by these processes while report running is unacceptable for
my production environment (response time grows from 1-3 seconds up to
1-2 minutes).

Is there any way to give different priorities to different
queries/transactions, as it's done for VACUUMing (vacuum_cost_*
options in config file)?

--
Leonid Safronie
DIAS-RIPE