On Thu, Feb 1, 2024 at 10:04 AM James Coleman <jtc331@gmail.com> wrote:
I don't see any inherent reason why we must always assume that gather_grouping_paths will always result in having at least one entry in pathlist. If, for example, we've disabled incremental sort and the cheapest partial path happens to already be sorted, then I don't believe we'll add any paths. And if that happens then set_cheapest will error with the message "could not devise a query plan for the given query". So I propose we add a similar guard to this call point.
I don't believe that would happen. It seems to me that we should, at the very least, have a path which is Gather on top of the cheapest partial path (see generate_gather_paths), as long as the partially_grouped_rel has partial paths.
