On 10/11/07, Andrew - Supernews <andrew+nonews@xxxxxxxxxxxxx> wrote: > On 2007-10-10, Theo Kramer <theo@xxxxxxxxxxx> wrote: > > When doing a 'manual' prepare and explain analyze I get the following > > > > rascal=# prepare cq (char(12), smallint, integer) as SELECT oid, > > calllog_mainteng, calllog_phase, calllog_self FROM calllog > > WHERE calllog_mainteng = $1 > > AND calllog_phase = $2 > > AND calllog_self < $3 > > OR calllog_mainteng = $1 > > AND calllog_phase < $2 > > ORDER BY calllog_mainteng DESC, > > calllog_phase DESC, > > calllog_self DESC limit 25; > > PREPARE > > When you do this from the application, are you passing it 3 parameters, > or 5? The plan is clearly taking advantage of the fact that the two > occurrences of $1 and $2 are known to be the same value; if your app is > using some interface that uses ? placeholders rather than numbered > parameters, then the planner will not be able to make this assumption. > > Also, from the application, is the LIMIT 25 passed as a constant or is that > also a parameter? also, this looks a bit like a drilldown query, which is ordering the table on 2+ fields. if that's the case, row wise comparison is a better and faster approach. is this a converted cobol app? merlin ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
