Stephan Szabo <sszabo@megazone23.bigpanda.com> writes:
>> statistic ( n_distinct in particular) records for one of my columns,
>> greatly under calculated it saying:
>> 49726, but in reality 33409816.
>> is it any way how I can improve that?
> You might see if raising the statistics target with ALTER TABLE ALTER
> COLUMN followed by an analyze helps getting reasonable values any. Maybe
> try a few thousand?
That seems like a big jump, considering the default is only 10. Try
setting it to 100 (then re-ANALYZE, then check the plan). If that
doesn't work, try more. I'd be interested to see what it takes to
get the estimate closer to reality.
regards, tom lane