Re: Index-only scans

Greg Stark <gsstark@mit.edu> wrote: 
> On Mon, Jul 13, 2009 at 7:04 PM, Kevin
> Grittner<Kevin.Grittner@wicourts.gov> wrote:
>> As far as our production queries go, based on our experience with
>> several other products against this schema, this is the area where
>> the biggest performance gains remain to be realized.
> 
> 
> There's a logical fallacy implicit in this statement. Namely that
> all potential performance gains out there are already implemented by
> other products :)
No, I'm basing it on having tested our application software with
various DBMS products and obtained benchmark timings.  PostgreSQL was
faster overall than products to which I compared it, but there were a
few standout slow queries under PostgreSQL.  When reviewing the plans
under the different products, the absence of particular optimizations
within PostgreSQL, present in the other products, became apparent.  I
don't base my observations on academic theory or speculation, even if
licensing agreements rarely allow me to share the supporting detail.
-Kevin