Re: "nice"/low priority Query

Tom Lane wrote:
> Tobias Brox  writes:
> 
>>Is there any ways to give postgresql a hint that a
>>particular SQL call should be run at lower priority?  Since every db
>>connection has a pid, I can manually run "renice" to scheduele it by the OS
>>- but of course I can't do it manually all the time.
> 
> And it won't help you anyway, because renice only affects CPU priority
> not I/O scheduling ... which, by your description, is the real problem.
> 
> I think the only thing that's likely to help much is trying to arrange
> that the "simple" queries only need to touch pages that are already in
> memory.  Some playing around with shared_buffer sizing might help.
> Also, if you're not on PG 8.0.*, an update might help.

Would it be useful to be able to re-use the vacuum_cost_xxx settings in 
8.0 for this sort of thing? I'm thinking a long-running report query 
isn't that different from a vacuum.

--
   Richard Huxton
   Archonet Ltd