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? -- Andrew, Supernews http://www.supernews.com - individual and corporate NNTP services ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
