On Nov 20, 2011, at 20:50, Phoenix Kiula <phoenix.kiula@xxxxxxxxx> wrote: > On Mon, Nov 21, 2011 at 7:26 AM, Gavin Flower > <GavinFlower@xxxxxxxxxxxxxxxxx> wrote: > >> How about having 2 indexes: one on each of ip & url_md5? Pg will combine the >> indexes as required, or will just use one if that is best. > > > > Thanks Gavin. Question: what if I have a joined index? If from a > joined index I only use the first column (say, "ip") will a joined > index still be used? > > It is cleaner to create two indexes for the two columns. Which is recommended? > An index on (a, b) can be used for queries involving only a but not for those involving only b. Neither is recommended - both have their benefits and limitations. David J. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
