I'm using PostgreSQL 8.3. Is it normal that plans using a scan on a partial unique index estimate that much more than one row is returned?
Eg. I see: -> Bitmap Index Scan on tmp_idx_oss_archive_object_id_current (cost=0.00..3.12 rows=4189 width=0) where the tmp_idx_oss_archive_object_id_current index is a partial unique index. The estimated row count would be correct for the whole table but obviously not for the part covered by the unique index. This happens to be a problem in this case because then the planner prefers a sequence scan on a table joined to this one and a hash join to an index scan and a nested loop join. Which takes hundreds of milliseconds instead of one, so setting enable_hashjoin to false increases performance immensely. -- Michał Politowski Talking has been known to lead to communication if practiced carelessly. -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
