Re: FETCH FIRST clause WITH TIES option

Tomas Vondra <tomas.vondra@2ndquadrant.com> writes:
> I've tried to fix the merge conflict (essentially by moving some of the
> code to adjust_limit_rows_costs(), but I'm wondering if the code added to
> create_limit_path is actually correct
> ...
> Firstly, this seriously needs some comment explaining why we do this.

I've not looked at this patch, but TBH I wonder why it is touching
planner rowcount estimation at all.  I find it doubtful either that
a correction for WITH TIES would be significant in most use-cases,
or that we could estimate it accurately if it was significant.
It certainly doesn't seem like something that needs to be messed
with in v1 of the feature.

            regards, tom lane