On Mon, Aug 31, 2026 at 5:57 PM Amit Langote <[email protected]> wrote: > On Sat, Aug 29, 2026 at 8:06 PM Ayush Tiwari > <[email protected]> wrote: > > On Thu, 27 Aug 2026 at 18:11, Amit Langote <[email protected]> wrote: > >> On Wed, Aug 26, 2026 at 10:25 PM Amit Langote <[email protected]> > >> wrote: > >> > On Sat, Aug 22, 2026 at 4:43 PM Amit Langote <[email protected]> > >> > wrote: > >> > > Pushed and closed the item. > >> > > >> > Ayush Tiwari reported another hole in the per-firing-cycle fix to me > >> > off-list. Here is his reproducer: > >> > > >> > CREATE TABLE pk (id int PRIMARY KEY); > >> > INSERT INTO pk VALUES (1); > >> > > >> > CREATE TABLE fk ( > >> > a int REFERENCES pk (id), > >> > b int CONSTRAINT fk_deferred REFERENCES pk (id) > >> > DEFERRABLE INITIALLY DEFERRED); > >> > > >> > CREATE FUNCTION check_now() RETURNS trigger LANGUAGE plpgsql AS $$ > >> > BEGIN > >> > BEGIN > >> > SET CONSTRAINTS fk_deferred IMMEDIATE; > >> > EXCEPTION WHEN foreign_key_violation THEN > >> > RAISE NOTICE 'caught by SET CONSTRAINTS'; > >> > END; > >> > RETURN NEW; > >> > END$$; > >> > > >> > -- Name sorts after the RI trigger, so column a is already batched. > >> > CREATE TRIGGER zz_check_now AFTER INSERT ON fk > >> > FOR EACH ROW EXECUTE FUNCTION check_now(); > >> > > >> > BEGIN; > >> > INSERT INTO fk VALUES (1, 999); > >> > > >> > On the current master with my fixes from last week, an > >> > assertion-enabled build produces: > >> > > >> > CREATE TABLE > >> > INSERT 0 1 > >> > CREATE TABLE > >> > CREATE FUNCTION > >> > CREATE TRIGGER > >> > BEGIN > >> > WARNING: resource was not closed: relation "pk_pkey" > >> > WARNING: resource was not closed: relation "pk" > >> > WARNING: resource was not closed: TupleDesc 0xffff812677f0 (16392,-1) > >> > WARNING: resource was not closed: TupleDesc 0xffff81270500 (16386,-1) > >> > server closed the connection unexpectedly > >> > This probably means the server terminated abnormally > >> > before or while processing the request. > >> > The connection to the server was lost. > >> > > >> > The relevant part of the backtrace is: > >> > > >> > #3 ExceptionalCondition (conditionName="false", > >> > fileName="../src/backend/utils/adt/ri_triggers.c", lineNumber=4543) > >> > #4 AtEOSubXact_RI (isCommit=true, mySubid=2, parentSubid=1) > >> > at ../src/backend/utils/adt/ri_triggers.c:4543 > >> > #5 CommitSubTransaction () > >> > at ../src/backend/access/transam/xact.c:5247 > >> > #6 ReleaseCurrentSubTransaction () > >> > at ../src/backend/access/transam/xact.c:4836 > >> > #7 exec_stmt_block (...) > >> > at ../src/pl/plpgsql/src/pl_exec.c:1859 > >> > > >> > SET CONSTRAINTS ... IMMEDIATE starts a nested firing cycle without > >> > opening a new query level, so keying the cache by constraint OID and > >> > query depth does not distinguish this cycle from the enclosing one. > >> > > >> > I am preparing a patch that uses firing depth, gives the SET > >> > CONSTRAINTS cycle its own callback list, and removes stale entries on > >> > either subtransaction commit or abort. I will post it shortly. > >> > >> Here is that patch. > >> > >> One thing missing from my report: the crash wasn't the worst of it. > >> The nested cycle's batch was never flushed, so SET CONSTRAINTS ... > >> IMMEDIATE returned success for a constraint it hadn't checked, and > >> the orphan row reached commit. > >> > >> I'm not proposing to commit this yet. I'm assessing whether the > >> batching layer holds up under a test harness and will give the RMT my > >> assessment by Monday on whether to keep it in v19. If the batching > >> layer is reverted from v19, this patch is master-only, assuming it's > >> ok for master to keep the layer in its current form. If it stays, it > >> belongs in both branches. I'm happy to commit and backpatch sooner if > >> that's preferred for the open item. > > > > > > Thanks for the patch. I'm aware that you are still testing this but wanted > > to > > add that I do see a problem when ALTER TABLE ... ADD FORIEGN KEY > > is run from an AFTER trigger. > > Thanks for the report. > > > I tried such a case in a non-cassert build, with RLS forcing the existing > > rows > > to be checked one at a time. The command appeared to succeed and the > > constraint was marked valid, even though the table still contained an orphan > > row. I also saw warnings about relation and TupleDesc resources not being > > closed. > > > > The reproducer I used was: > > > > CREATE ROLE fp_alter_role; > > CREATE TABLE fp_alter_pk (id int PRIMARY KEY); > > INSERT INTO fp_alter_pk VALUES (1); > > ALTER TABLE fp_alter_pk ENABLE ROW LEVEL SECURITY; > > CREATE POLICY fp_alter_pk_all ON fp_alter_pk USING (true); > > GRANT REFERENCES, SELECT ON fp_alter_pk TO fp_alter_role; > > > > CREATE TABLE fp_alter_fk (a int); > > INSERT INTO fp_alter_fk VALUES (1), (999); > > ALTER TABLE fp_alter_fk OWNER TO fp_alter_role; > > > > CREATE TABLE fp_alter_outer (a int); > > ALTER TABLE fp_alter_outer OWNER TO fp_alter_role; > > > > CREATE FUNCTION fp_alter_from_trigger() RETURNS trigger > > LANGUAGE plpgsql AS $$ > > BEGIN > > BEGIN > > EXECUTE 'ALTER TABLE fp_alter_fk ADD CONSTRAINT ' > > 'fp_alter_bad_fk FOREIGN KEY (a) ' > > 'REFERENCES fp_alter_pk(id)'; > > EXCEPTION WHEN others THEN > > RAISE; > > END; > > RETURN NEW; > > END > > $$; > > > > CREATE TRIGGER fp_alter_trg > > AFTER INSERT ON fp_alter_outer > > FOR EACH ROW EXECUTE FUNCTION fp_alter_from_trigger(); > > > > SET ROLE fp_alter_role; > > INSERT INTO fp_alter_outer VALUES (1); > > RESET ROLE; > > > > SELECT conname, convalidated > > FROM pg_constraint > > WHERE conname = 'fp_alter_bad_fk'; > > TABLE fp_alter_fk; > > > > Could the validation calls be joining the outer trigger's batch because > > AfterTriggerIsActive() is true, and then be removed by AtEOSubXact_RI() > > before > > they are checked? The validation path sets trig.tgoid to InvalidOid, so > > would > > it make sense to use that to keep these calls on the non-batched path? > > Your diagnosis is correct; tgoid would work. Though, I'd rather make > the caller state that explicitly instead of gleaning it from > trigger.c-internal state, which is what I should have done originally. > Add a allow_batch parameter to RI_FKey_check() and new validation > function called from ALTER TABLE code, instead of RI_FKey_check_ins(), > which calls RI_FKey_check() with 'false' for allow_batch. Attached > 0001 does that and also contains your test case. 0002 unchanged.
Added a separate open item for this, so there are two for 0001 and 0002, resp. Fixed by 0001 (just added): RI fast-path batching wrongly used by ALTER TABLE inside a trigger Commit: b7b27eb41a5 Owner: Amit Langote Fixed by 0002: RI fast-path batching fails during nested SET CONSTRAINTS Commit: 6fc2a486417d Owner: Amit Langote -- Thanks, Amit Langote
