Hello Amit,
Thank you for your help. You are right, it work fine with PostgreSQL 9.2. *Ghislain ROUVIGNAC* 2013/6/6 Amit Kapila <amit.kap...@huawei.com> > > On Thursday, June 06, 2013 1:56 PM Ghislain ROUVIGNAC wrote: > > Hello, > > > > We have a strange issue related to a prepared statement. > > > > We have two equals queries where the sole difference is in the limit. > > - The first is hard coded with limit 500. > > - The second is prepared with limit $1 ($1 is bound to 500). > > > > PostgreSQL give us two different plans with a huge execution time for the > prepared query: > > It can generate different plan for prepared query, because optimizer uses > default selectivity in case of bound parameters (in your case limit $1). > > > > We met the same behaviour with both : > > - PostgreSQL 8.4.8 on Windows 2008 (Prod) > > - PostgreSQL 8.4.8 and 8.4.17 on Windows 7 (Dev) > > From PostgreSQL 9.2, it generates plan for prepared query during execution > (Execute command) as well. > So I think you will not face this problem in PostgreSQL 9.2 and above. > > With Regards, > Amit Kapila. > >
