Re: why partition pruning doesn't work?

David Rowley <david.rowley@2ndquadrant.com> writes:
> On 8 June 2018 at 03:43, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Maybe there's something I'm missing here, but I sort of hoped that this
>> patch would nuke all the special-case code for Params in this area.
>> Why is there any need to distinguish them from other stable expressions?

> We need to know which Params exist in the Expr as if there are no
> Params, or only external Params, then we can run-time prune during
> startup of the executor.

This does not refute my question.  Why doesn't the same logic apply
to any stable expression?  That is, ISTM a Param is a special case
of that.

            regards, tom lane