On Thu, 19 Sep 2002, Rajesh Kumar Mallah. wrote: > I am trying to improve a query to use existing indexes but facing diffculty. > > > Looks like 'between' amd '>=' are not using indexes althoug > and < does. > all my application code uses between and i am sure it use to work fine > at one point of time. > > > regds > mallah. > > SQL TRANSCRIPT: > >====================================================================================== > > tradein_clients=> explain select list_id from eyp_rfi a where generated > >'2002-08-13' and generated < '2002-09-19' ; > NOTICE: QUERY PLAN: > > Index Scan using eyp_rfi_date on eyp_rfi a (cost=0.00..15796.97 rows=4150 width=4) > > EXPLAIN > tradein_clients=> explain select list_id from eyp_rfi a where generated >= >'2002-08-13' and generated < '2002-09-19' ; > NOTICE: QUERY PLAN: > > Seq Scan on eyp_rfi a (cost=0.00..17923.81 rows=5061 width=4)
Given how close the two results are (and the fact that they differ by 900 rows), have you tried using set enable_seqscan=off and seeing what explain gives you for the second query? My guess is that it'll have an estimated cost greater than the 17923.81 it's estimating from the sequence scan. ---------------------------(end of broadcast)--------------------------- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
