On Sun, May 19, 2013 at 8:44 PM, Greg Smith <greg@xxxxxxxxxxxxxxx> wrote: > On 5/13/13 6:36 PM, Mike McCann wrote: >> >> stoqs_march2013_s=# explain analyze select * from >> stoqs_measuredparameter order by datavalue; >> >> QUERY PLAN >> >> ------------------------------------------------------------------------------------------------------------------------------------------ >> Sort (cost=422106.15..430560.68 rows=3381814 width=20) (actual >> time=2503.078..2937.130 rows=3381814 loops=1) >> Sort Key: datavalue >> Sort Method: quicksort Memory: 362509kB >> -> Seq Scan on stoqs_measuredparameter (cost=0.00..55359.14 >> rows=3381814 width=20) (actual time=0.016..335.745 rows=3381814 >> loops=1) >> Total runtime: 3094.601 ms >> (5 rows) >> >> I tried changing random_page_cost to from 4 to 1 and saw no change. > > > Have you tried putting an index by datavalue on this table? Once you've > done that, then changing random_page_cost will make using that index look > less expensive. Sorting chews through a good bit of CPU time, and that's > where all of your runtime is being spent at--once you increase work_mem up > very high that is. This++ plus cluster on that index if you can. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
