On Wed, Nov 16, 2011 at 7:42 PM, Tory M Blue <tmblue@xxxxxxxxx> wrote: > On Wed, Nov 16, 2011 at 6:27 PM, Tomas Vondra <tv@xxxxxxxx> wrote: >> On 17 Listopad 2011, 2:57, Scott Marlowe wrote: >>> On Wed, Nov 16, 2011 at 4:59 PM, Tomas Vondra <tv@xxxxxxxx> wrote: >>> >>>> But you're right - you're not bound by I/O (although I don't know what >>>> are >>>> those 15% - iowait, util or what?). The COUNT(DISTINCT) has to actually >>>> keep all the distinct values to determine which are actually distinct. >>> >>> Actually I meant to comment on this, he is IO bound. Look at % Util, >>> it's at 99 or 100. >>> >>> Also, if you have 16 cores and look at something like vmstat you'll >>> see 6% wait state. That 6% represents one CPU core waiting for IO, >>> the other cores will add up the rest to 100%. >> >> Aaaah, I keep forgetting about this and I somehow ignored the iostat >> results too. Yes, he's obviously IO bound. > > I'm not so sure on the io-bound. Been battling/reading about it all > day. 1 CPU is pegged at 100%, but the disk is not. If I do something Look here in iostat: > Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s > avgrq-sz avgqu-sz await svctm %util > sda 0.00 3.50 3060.00 2.00 49224.00 20.00 > 16.08 2.21 0.76 0.33 99.95 See that last column, it's % utilization. Once it hits 100% you are anywhere from pretty close to IO bound to right on past it. I agree with the previous poster, you should roll these up ahead of time into a materialized view for fast reporting. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
