On Mon, Sep 22, 2008 at 2:40 PM, Sabin Coanda <sabin.coanda@xxxxxxxxxxxxx> wrote: > Hi there, > > I am still concerned about this problem, because there is a big differences > between the two cases, and I don't know how to identify the problem. Can > anybody help me, please ? Sure, first step, if you can provide the following: pg version os and version output of explain analyze of each query (one good query, one bad) In the meantime, make sure you've vacuum analyzed your db.