The combination index works great. Would adding the combination index guarantee that the optimizer will choose that index for these kind of queries involving the columns in the combination. I verified a couple of times and it picked the right index. Just wanted to make sure it does that consistently. On Tue, Jun 22, 2010 at 7:01 PM, Tom Lane <tgl@xxxxxxxxxxxxx> wrote: > Alvaro Herrera <alvherre@xxxxxxxxxxxxxxxxx> writes: >> Excerpts from Anj Adu's message of mar jun 22 17:44:39 -0400 2010: >>> This query seems unreasonable slow on a well-indexed table (13 million >>> rows). Separate indexes are present on guardid_id , from_num and >>> targetprt columns. > >> Maybe you need to vacuum or reindex? > > Rethinking the set of indexes is probably a more appropriate suggestion. > Separate indexes aren't usefully combinable for a case like this --- in > principle the thing could do a BitmapAnd, but the startup time would be > pretty horrid, and the LIMIT 1 is discouraging it from trying that. > If this is an important case to optimize then you need a 3-column index. > > regards, tom lane > -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
