Chris <dmagick@xxxxxxxxx> writes: > Robert James wrote: >> Hi. I'm seeing some weird behavior in Postgres. I'm running read only >> queries (SELECT that is - no UPDATE or DELETE or INSERT is happening at >> all). I can run one rather complicated query and the results come >> back... eventually. Likewise with another. But, when I run both >> queries at the same time, Postgres seems to ground to a halt. > They're probably not blocking each other but more likely you're > exhausting your servers resources. If they return "eventually" > individually, then running both at the same time will take at least > "eventually x2". It could be a lot more than x2. If the two queries together eat enough RAM to drive the machine into swapping, where it didn't swap while doing one at a time, the slowdown could be orders of magnitude. Watching vmstat output might be informative --- it would at least give an idea if the bottleneck is CPU, I/O, or swap. regards, tom lane -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
