Alvaro Herrera wrote: > That's not a problem because it's just a limit. It won't cause out of > memory or anything. Ah, I see. Well, it's nice to have caught that anyway, I suppose. > The problem with work_mem is that the system may request that much > memory for every Sort step. Each query may have more than one of those, > and each backend can be serving more than one query at a time. So those > 200000 you have quickly turn into the gigabytes and consume the whole of > your RAM. > > If a Sort step requires more than work_mem for its work, it will go to > disk -- but in a much faster way than what the kernel is able to do with > swap. So whenever you are trading work_mem for swap, you are losing big > time. You should decrease that figure. Thanks for that bit of advice, Alvaro. I did not know that a work_mem is allocated for each sort step. I will try lowering work_mem gradually until it impacts performance. Though even if this fixes my problem, I'm still bothered by swap never being used. (Not that I expect you to come up with a magic answer for me.) Thank you, Mark
