On Sat, Jul 11, 2026 at 5:42 AM Noah Misch <[email protected]> wrote: > On Wed, Jul 16, 2025 at 12:55:44AM +0300, Alexander Korotkov wrote: > > On Wed, Jun 4, 2025 at 11:52 PM Alexander Korotkov <[email protected]> > > wrote: > > > On Wed, Jun 4, 2025 at 6:15 PM Alexander Pyhalov > > > <[email protected]> wrote: > > > > Alexander Korotkov писал(а) 2025-06-04 14:29: > > > > > On Wed, Jan 29, 2025 at 11:59 AM Maxim Orlov <[email protected]> > > > > > wrote: > > > > >> One important note here. This patch will change cast behaviour in > > > > >> case > > > > >> of local and foreign types are mismatched. > > > > >> The problem is if we cannot convert types locally, this does not mean > > > > >> that it is also true for a foreign wrapped data. > > > > >> In any case, it's up to the committer to decide whether this change > > > > >> is > > > > >> needed or not. > > > > > > > > > > I have two question regarding this aspect. > > > > > 1) Is it the same with regular type conversion? > > > > > > > > Yes, it's the same. > > > > > > > > CREATE TYPE enum_of_int_like AS enum('1', '2', '3', '4'); > > > > CREATE TABLE conversions(id int, d enum_of_int_like); > > > > CREATE FOREIGN TABLE ft_conversions (id int, d char(1)) > > > > SERVER loopback options (table_name 'conversions'); > > > > SET plan_cache_mode = force_generic_plan; > > > > PREPARE s(varchar) AS SELECT count(*) FROM ft_conversions where d=$1; > > > > EXPLAIN (VERBOSE, COSTS OFF) > > > > EXECUTE s('1'); > > > > QUERY PLAN > > > > ------------------------------------------------------------------------------------------- > > > > Foreign Scan > > > > Output: (count(*)) > > > > Relations: Aggregate on (public.ft_conversions) > > > > Remote SQL: SELECT count(*) FROM public.conversions WHERE ((d = > > > > $1::character varying)) > > > > (4 rows) > > > > > > > > EXECUTE s('1'); > > > > ERROR: operator does not exist: public.enum_of_int_like = character > > > > varying > > > > HINT: No operator matches the given name and argument types. You might > > > > need to add explicit type casts. > > > > Got it, thank you for the explanation. I thin it's fair that array > > > coercion works the same way as a regular cast. > > I agree with that principle. While the above example shows regular and array > casts aligned, Fable 5 found the attached test cases where that alignment is > absent, yielding array-specific wrong query result scenarios. This thread's > commit 62c3b4c introduced those. I think the test patch's "implicit-format > ArrayCoerceExpr" is not meaningfully a regression, because scalars have the > same problem. The other two, "pushed down although the element conversion > calls a cast" and "CoerceViaIO are pushed down", are array-specific > regressions. Scalars don't get corresponding trouble for those two. I'm also > attaching Fable 5's report. > > > I've written a commit message for this patch. I'm going to push this > > if no objections.
Thank you for catching this. The fix is attached. It ships ArrayCoerceExpr only when its element expression is RelabelType or CaseTestExpr. I propose to backpatch it to pg 19. And we can consider shipping ArrayCoerceExpr with shippable element cast functions for pg 20. ------ Regards, Alexander Korotkov Supabase
v1-0001-postgres_fdw-don-t-push-down-non-relabeling-Array.patch
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