On Tue, 23 Jul 2002, Daryl Herzmann wrote: > > >On Tue, 23 Jul 2002, Daryl Herzmann wrote: > > > >> snet=# explain analyze select * from t2002_06 WHERE station = 'SAMI4'; > >> NOTICE: QUERY PLAN: > >> > >> Seq Scan on t2002_06 (cost=0.00..35379.69 rows=34979 width=47) (actual > >> time=67.89..3734.93 rows=38146 loops=1) > >> Total runtime: 3748.33 msec > >> > >> EXPLAIN > >> > >> snet=# set enable_seqscan=off; > >> SET VARIABLE > >> snet=# explain analyze select * from t2002_06 WHERE station = 'SAMI4'; > >> NOTICE: QUERY PLAN: > >> > >> Index Scan using t2002_06_station_idx on t2002_06 (cost=0.00..132124.96 > >> rows=34979 width=47) (actual time=72.03..298.85 rows=38146 loops=1) > >> Total runtime: 317.76 msec > > > >Looks like the estimated cost is way divorced from reality. Is the > >34979 row estimate even realistic and how well ordered is the table > >(actually output from pg_statistic would be good as well :) ). > > Thanks for the help! I am not sure if I can answer your questions. I will > try :) > > I believe the row estimate is realistic based on this value. > > snet=# select count(*) from t2002_06 WHERE station = 'SAMI4'; > count > ------- > 38146
> I am really sorry, but I don't know what to output from pg_statistic. I > searched around on the Internet and was not sure what to send you from > this table. Sorry :( Right... sorry about that... select * from pg_statistic where starelid=(select oid from pg_class where relname='t2002_06'; ---------------------------(end of broadcast)--------------------------- TIP 6: Have you searched our list archives? http://archives.postgresql.org
