Re: BUG #17540: Prepared statement: PG switches to a generic query plan which is consistently much slower

David Rowley <dgrowleyml@gmail.com> writes:
> Anyway, I've no current plans to take the attached any further. I
> think it'll be better to pursue your NULLable-Var stuff and see if we
> can do something more generic like remove provably redundant NullTests
> from baserestrictinfo.

Yeah, I suspect that the way forward is to allow
preprocess_minmax_aggregates to do what it does now, and then
remove the IS NOT NULL clause again later when we have the
info available to let us do that in a generic way.

In any case, as you said, it's just a band-aid that happens to
help in this exact scenario.  It's not doing much for the bad
cost estimation that's the root of the problem.

            regards, tom lane