"Kevin Grittner" <kevin.gritt...@wicourts.gov> wrote: <> p...@elbrief.de> wrote: > >> insert into bla ( a , b ) >> select a , a >> from generate_series( 1 , 1000000 ) as a ( a ) ; > >> explain analyze select * from bla >> where b > 990000 order by a limit 10 ; >> [uses index on b and has a long run time] > > The problem is that PostgreSQL doesn't have any sense of the > correlation between columns a and b (i.e., they are always equal) A belated thought on this -- you went right from your load to running queries without leaving any time for autovacuum to kick in and generate statistics. I recommend that somewhere after you insert the data and before you run your selects, you run: VACUUM ANALYZE bla; This will get you to something which more closely resembles a "steady state" environment. -Kevin
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