Hello! I have this table: create table test ( s1 varchar(255), s2 varchar(255), i1 integer, i2 integer, ... over 100 other fields ); table contains over 8 million records there's these indexes: create index is1 on test (s1); create index is2 on test (s2); create index ii1 on test (i1); create index ii2 on test (i2); create index ii3 on test (i1, i2); and then i run this query: select * from ( select * from test where is1 = 'aa' or is2 = 'aa' ) where is1 = 1 or (is1 = 1 and is2 = 1) or (is1 = 2 and is2 = 2) or (is1 = 3 and is2 = 3) where part of outer query can have different count of "or (is1 = N and is2 = M)" expressions, lets name this number X. When X is low planner chooses index scan using is1 and is2, then BitmapAnd that with index scan using ii1, ii2 or ii3. But when X is big enough (> 15) planner chooses seqscan and filter on i1, i2, s1, s2. Seqscan is very slow and I want to avoid it. Subquery is very fast and i don't know why postgres chooses that plan. I know I can set enable_seqscan = off. Is there other ways to enforce index usage? postgres pg_class have right estimate of rowcount. -- A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail? -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
