Re: Fix generate_useful_gather_paths for parallel unsafe pathkeys

Hi,

I reviewed the patch series, tweaked a couple comments, added commit
messages etc. Barring objections, I'll push this in a couple days.

One thing that annoys me is that it breaks ABI because it adds two new
parameters to find_em_expr_usable_for_sorting_rel, but I don't think we
can get around that. We could assume require_parallel_safe=true, but we
still need to pass the PlannerInfo pointer.


regards

-- 
Tomas Vondra
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company