Heikki Linnakangas <heikki.linnakan...@enterprisedb.com> writes: > On 21.12.2010 21:25, Jesper Krogh wrote: >> Or is a Bitmap Heap Scan simply 3 times faster than a Seq-scan for >> visibillity-testing?
> It certainly shouldn't be. >> What have I missed in the logic? > Perhaps you have a lot of empty space or dead tuples that don't match > the query in the table, which the sequential scan has to grovel through, > but the bitmap scan skips? What does EXPLAIN ANALYZE of both queries say? Another possibility is that the seqscan is slowed by trying to operate in a limited number of buffers (the buffer strategy stuff). regards, tom lane -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers