Re: add_path optimization

disclaimer: I don't know that bit of postgresql code, in fact - this
is the first time I see it.

*** a/src/backend/optimizer/path/joinpath.c
--- b/src/backend/optimizer/path/joinpath.c
***************
*** 473,478 **** match_unsorted_outer(PlannerInfo *root,
--- 473,481 ----

if (nestjoinOK)
{
+ Path *paths[5];

I don't like the fact that you hardcoded that here. I know that you
are trying to pass on few calls in one go here, but still... ugly.

static int
compare_fuzzy_path_costs(Path *path1, Path *path2, int *startup_cost)
{
....
*startup_cost = (s == 0) ? t : s;

Why not *startup_cost = s, and let the caller decide which value it
wants to use ?
or just return both, from single call (which would ?
...

return t;
}

To be fair, I don't see compare_fuzzy_path_costs change to save too
much of time in planner.
I would myself probably convert that function into two defines/inline
funcs, but that's just me.