"Vyacheslav Kalinin" <vka@xxxxxxxx> writes: > [ poor estimation for ] > select * > from cities > where ( ficity_id in ( > select ficity_id from cities_name_words > where fsword like 'novgorod%' > union > select ficity_id from cities_name_ru_words > where fsword like 'novgorod%' > ) > or lower(fsname) like 'novgorod%' > or lower(fsname_ru) like 'novgorod%' > ) When you have an IN at the top level of WHERE, it's flattened into a kind of JOIN, and there's reasonably decent estimation of the selectivity. Unfortunately, when it's down inside an OR-clause like this, all those smarts go out the window and it's just treated as a generic subplan condition, with 0.5 estimated selectivity IIRC. Improving that would be nice but it's not high on anyone's to-do list. You might get better results if you combine three separate queries with UNION. 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
