On 7/11/06, Alvaro Herrera <alvherre@commandprompt.com> wrote:
> Guido Neitzer wrote:
> > On 11.07.2006, at 19:36 Uhr, Merlin Moncure wrote:
> > It is not, as prepared statements have the problem that they are only
> > optimized once and very generically and without actual knowledge of
> > the parameter content, this is just useless.
> >
> > I had the problem a few months ago, where my app server plugin and
> > the jdbc driver used prepared statements for selecting stuff from the
> > database. Most of the time, indexes weren't used at all, so
> > PostgreSQL performance was the worst I've ever seen in this environment.
>
> I'm pretty excited about this idea of yours on how to fix this problem.
> Does it involve the histogram at all?
I've thought for a long time the best way to handle this problem is to
allow supplying a hint for any parameter. For example, I like to
paramterize the limit statement whicih is actually pretty neat but the
planner (iirc) assumes 10% and so resorts to seqscan/bitmapscan in
these cases.
Merlin
