"Shane Wright" <shane.wright@xxxxxxxxxxxxxxxxxxxx> writes: > Tom, >> You need to >> look into what the estimated vs actual rowcounts are for just the >> two-column condition (ie, where nid = something AND iid1 = something). > Improving the accuracy of the cost estimates is exactly what I'm trying > to achieve, so far I've tried.... > - increasing the statistics target to the maximum setting with SET > STATISTICS 1000 on columns rid, nid and iid1 of answers, then > re-vacuuming I hope you meant re-analyzing. > emystery=# explain analyse select * FROM ecos_answers WHERE > nid=253869913 AND iid1=535292129; > QUERY PLAN > ------------------------------------------------------------------------ > ------------------------------------------------------------------------ > --- > Index Scan using index_ecos_answers_nidiid1 on ecos_answers > (cost=0.00..114.14 rows=1 width=60) (actual time=0.206..2398.645 > rows=21891 loops=1) > Index Cond: ((nid = 253869913) AND (iid1 = 535292129)) > Total runtime: 2424.769 ms > (3 rows) Well, here's the problem all right: 1 row estimated vs 21891 actual. Is there something odd about the joint distribution of these two columns? regards, tom lane -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
