Re: Remove some redundant set_cheapest() calls

On Wed, Mar 27, 2024 at 4:06 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Richard Guo <guofenglinux(at)gmail(dot)com> writes:
> > I happened to notice that the set_cheapest() calls in functions
> > set_namedtuplestore_pathlist() and set_result_pathlist() are redundant,
> > as we've centralized the set_cheapest() calls in set_rel_pathlist().
>
> > Attached is a trivial patch to remove these calls.
>
> Agreed, and pushed.

Thanks for pushing!

> > BTW, I suspect that the set_cheapest() call in set_dummy_rel_pathlist()
> > is also redundant. The comment there says "This is redundant when we're
> > called from set_rel_size(), but not when called from elsewhere". I
> > doubt it. The other places where it is called are set_append_rel_size()
> > and set_subquery_pathlist(), both being called from set_rel_size(). So
> > set_cheapest() would ultimately be called in set_rel_pathlist().
>
> I'm less convinced about changing this. I'd rather keep it consistent
> with mark_dummy_rel.

Hm, I wonder if we should revise the comment there that states "but not
when called from elsewhere", as it does not seem to be true.

Thanks
Richard