On Oct 7, 2013, at 11:34, Toni Helenius <toni.helen...@syncrontech.com> wrote:
> Hi, > > yes, I'm cheating by using GUI :) (PgAdmin) Please do not top-post. Analyze is an entirely different command than Explain analyze. Analyze updates the statistics of tables, while Explain analyze tells how those statistics affect the query plan. > Here: > > "Aggregate (cost=18240.50..18240.51 rows=1 width=0) (actual > time=2911.117..2911.119 rows=1 loops=1)" > " -> Seq Scan on min1_009 (cost=0.00..18108.60 rows=52760 width=0) (actual > time=5.390..2816.274 rows=52760 loops=1)" > "Total runtime: 2912.211 ms" That article you referenced mentions pg_class.relallvisible - what value does that have for your table? Is it possible that a relatively large amount of the data in that table is not visible to other sessions, or was that perhaps the case when you last (vacuum) analyzed the table? What is the plan if you set enable_seqscan = off; in your session? Does that give any more insight? > -----Original Message----- > From: Alban Hertroys [mailto:haram...@gmail.com] > Sent: 7. lokakuuta 2013 12:31 > To: Toni Helenius > Cc: pgsql-general@postgresql.org > Subject: Re: [GENERAL] Index only select count(*) > > On Oct 7, 2013, at 11:23, Toni Helenius <toni.helen...@syncrontech.com> wrote: > >> The output of analyze: >> "Aggregate (cost=18240.50..18240.51 rows=1 width=0)" >> " -> Seq Scan on min1_009 (cost=0.00..18108.60 rows=52760 width=0)" > > That's the output of Explain, not of Explain Analyze. The latter has actual > measurements to go with the estimated costs, which gives a lot more insight. > > Alban Hertroys > -- > If you can't see the forest for the trees, cut the trees and you'll find > there is no forest. > Alban Hertroys -- If you can't see the forest for the trees, cut the trees and you'll find there is no forest. -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
