> > On Oct 7, 2013, at 11:34, Toni Helenius > > <Toni.Helenius@xxxxxxxxxxxxxxx> > > 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? > > Hmm, yes I didn't check these before. > SELECT pg_class.relname, pg_class.relallvisible, pg_class.relpages FROM > pg_class where pg_class.relname = 'min1_009'; > "min1_009";0;17581 > > So no pages are visible? How come? They should be? The schema I'm on > has GRANT ALL ON SCHEMA "SERIES" TO public; Hmm, I was able to get an index-only scan and get all pages to be visible by doing the VACUUM in the same session. Running VACUUM from PgAdmin GUI didn't have any effect. This did the trick: VACUUM "SERIES".min1_009; EXPLAIN ANALYZE SELECT count(*) FROM "SERIES".min1_009; But I'm still confused about this, do I need to log in on the database with the login I use and manually do the vacuum? Because auto-vacuum doesn't update the visibility maps for that user or session or something? Should auto-vacuum do this? > > 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:haramrae@xxxxxxxxx] > > > Sent: 7. lokakuuta 2013 12:31 > > > To: Toni Helenius > > > Cc: pgsql-general@xxxxxxxxxxxxxx > > > Subject: Re: Index only select count(*) > > > > > > On Oct 7, 2013, at 11:23, Toni Helenius > > <Toni.Helenius@xxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxx) To > make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-general -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
