Re: Optimizing prepared statements

"Jeroen T. Vermeulen" <jtv@xs4all.nl> writes:
> On Sun, September 3, 2006 23:52, Tom Lane wrote:
>> What exactly do you mean by "optimize away a parameter"?  The way you
>> described the mechanism, there are no parameters that are "optimized
>> away", you've merely adjusted selectivity predictions using some assumed
>> values.

> I'm using "optimized away" as shorthand for "replaced with a literal
> constant in the statement definition used to generate the plan."

Ah.  I think you're confusing the spectators by using "predict" when you
should say "match".  You're looking for previously generated plans that
have assumed parameter values matching the current query --- saying that
the plan "predicts" a parameter value is just a really poor choice of
wording.
        regards, tom lane