On Wed, 10 Sept 2025 at 16:26, Ashutosh Bapat <ashutosh.bapat....@gmail.com> wrote: > > On Wed, Sep 10, 2025 at 4:27 AM David Rowley <dgrowle...@gmail.com> wrote: > > This seems quite separate from what's being complained about here. It > > might be beneficial to reconsider whether we should do some sort of > > sorting on startup_subpaths inside add_paths_to_append_rel(). I > > imagine that it might make some sense to sort that list so the path > > with the cheapest startup cost is first, then put the remainder of the > > list in order of cheapest total cost per tuple. I suspect that would > > result in Foreign partitions being scanned last... > > If there's LIMIT without ORDER BY, we could order the list of subpaths > by the number of rows in descending order or cost per row in ascending > order. That way there are more chances of scanning fewer partitions > quicker.
Wouldn't that amount to favouring scanning some large foreign partition over a smaller local partition? My interpretation of Andrei's "Prefer scanning local partitions to foreign ones" statement is that was what we shouldn't be doing! David
