2013/12/18 kolsze...@gmail.com <kolsze...@gmail.com> > Thanx for your answer > > My example is trivial because i want to show strange (for me) postgres > behavior with dealing with primary keys (extreme example), in real > situation > user put search condition e.g. "Panas" and this generates query > ... > where gd.other_code like 'Panas%' OR g.code like 'Panas%' > .. > > both columns has very good indexes and selectivity for "like 'Panas%'" ... > > I have experience from Oracle with this type of queries, and Oracle have no > problem with it, > executes select on index on other_code from gd and join g > in next step executes select on index on code from g and join gd > and this two results are connected in last step (like union) > very fast on minimal cost > > and in my opinion read whole huge tables only for 10 rows in result where > conditions are very good ... is strange > > Maybe index is not in good form
try to build index with varchar_pattern_ops flag http://postgres.cz/wiki/PostgreSQL_SQL_Tricks_I#LIKE_optimalization CREATE INDEX like_index ON people(surname varchar_pattern_ops); Regards Pavel Stehule > > > > > > > > > -- > View this message in context: > http://postgresql.1045698.n5.nabble.com/Problem-with-slow-query-with-WHERE-conditions-with-OR-clause-on-primary-keys-tp5782803p5783927.html > Sent from the PostgreSQL - performance mailing list archive at Nabble.com. > > > -- > Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-performance >
