On Thu, Jun 11, 2026 at 6:51 PM Junwang Zhao <[email protected]> wrote: > On Thu, Jun 11, 2026 at 5:05 PM Amit Langote <[email protected]> wrote: > > > > On Thu, Jun 11, 2026 at 5:18 PM Junwang Zhao <[email protected]> wrote: > > > I only reviewed and applied patch 0001 on my local machine, and it > > > successfully fixed the crash. > > > > > > One minor comment: > > > > > > + if (fpentry->flushing) > > > + { > > > + ri_FastPathCheck(riinfo, fk_rel, newslot); > > > + return; > > > + } > > > > > > Would it be worth wrapping the condition with unlikely()? It seems > > > this branch is expected to be false in most cases, not a strong > > > opinion though. > > > > Good idea. Will do. > > > > Are you planning to look at 0002? > > I just applied 0002 and ran the regression successfully. > > I have one trivial comment, subXact abort doesn't NULL the > ri_fastpath_cache, so I think the following comment of > RI_FastPathEntry should be polished accordingly by removing the > `SubXactCallback`. > > * ri_FastPathEndBatch(); on abort, ResourceOwner releases the cached > * relations and the XactCallback/SubXactCallback NULL the static cache pointer > * to prevent any subsequent access.
Thanks for the review. Yes, I missed that. I've updated the patches to address your comments and did some other polishing. -- Thanks, Amit Langote
From 00e3f4ff89b3c533899eb996be4e98e3ee82c63c Mon Sep 17 00:00:00 2001 From: Amit Langote <[email protected]> Date: Wed, 10 Jun 2026 21:11:10 +0900 Subject: [PATCH v3 2/2] Confine RI fast-path batching to the top transaction level The FK fast-path batching added in b7b27eb41a5 buffers rows in a transaction-lived cache (ri_fastpath_cache) keyed by constraint OID. Running user-defined cast and equality functions during a batch flush, together with the cache's lifetime and iteration, exposed two defects reachable by an unprivileged table owner. First, on subtransaction abort ri_FastPathSubXactCallback discarded the entire cache. An entry's batch holds rows buffered by the enclosing transaction, not just the aborting subxact -- the cache is keyed by constraint, so a single entry can mix rows from multiple subxact levels. An internal subxact abort during after-trigger firing (e.g. a PL/pgSQL BEGIN ... EXCEPTION block) therefore dropped buffered rows of the outer transaction without running their FK checks, letting orphan rows commit behind a constraint that still reported itself valid. The discard also left relations opened by the batch unclosed, producing "resource was not closed" warnings. Second, ri_FastPathEndBatch flushes by iterating the cache with hash_seq_search. If flush-time user code inserts into a different fast-path FK table, a new entry is added to the cache mid-scan; it may land in a bucket the scan has already passed and never be reached, and ri_FastPathTeardown then destroys the cache without flushing it, silently dropping that check. Cleanly unwinding the cache on subxact abort would require tracking the originating subxact of each buffered row, since rows from different levels share an entry (the cache is keyed by constraint) and deferred constraints cannot be flushed early at a subxact boundary. Rather than add that bookkeeping, confine batching to the top transaction level: in RI_FKey_check, when GetCurrentTransactionNestLevel() > 1, use the per-row fast path (ri_FastPathCheck) instead of buffering. Rows checked inside a subtransaction are then verified immediately and roll back cleanly with their subtransaction, and the cache only ever holds top-level rows. With the cache confined to the top level, a subtransaction abort has nothing of its own to discard, so ri_FastPathSubXactCallback is removed along with its registration. For the second defect, add a cache-wide flag (ri_fastpath_flushing) set while ri_FastPathEndBatch iterates the cache. A re-entrant FK check arriving while the flag is set takes the per-row path rather than adding an entry to the cache being scanned, so no entry can be missed and torn down unflushed. The flag is cleared in a PG_FINALLY so a flush that throws (a reported violation or an error from user code) does not leave it stuck. As defensive insurance it is also cleared in ri_FastPathXactCallback() at transaction end. The per-row fast path still bypasses SPI and stays well ahead of the pre-19 SPI-based check. A fuller fix that preserves batching across subtransactions -- whether by tracking the originating subxact of each buffered row or by per-subxact cache stacks merged into the parent on commit -- is left for a future release. The subtransaction-abort case is covered by a new regression test. The mid-scan cross-table case depends on hash bucket placement and so is not reliably reproducible in a portable test, but the flag prevents it by construction. Reported-by: Nikolay Samokhvalov <[email protected]> Reviewed-by: Nikolay Samokhvalov <[email protected]> Reviewed-by: Ayush Tiwari <[email protected]> Discussion: https://postgr.es/m/CAM527d9exRCdWrhJOnAxk_vACg7sr_yPoaJp_+uCFY0qP8v=aw@mail.gmail.com --- src/backend/utils/adt/ri_triggers.c | 86 +++++++++++++++-------- src/test/regress/expected/foreign_key.out | 24 +++++++ src/test/regress/sql/foreign_key.sql | 23 ++++++ 3 files changed, 105 insertions(+), 28 deletions(-) diff --git a/src/backend/utils/adt/ri_triggers.c b/src/backend/utils/adt/ri_triggers.c index 917a544c32b..06e7728c45d 100644 --- a/src/backend/utils/adt/ri_triggers.c +++ b/src/backend/utils/adt/ri_triggers.c @@ -228,8 +228,8 @@ typedef struct RI_CompareHashEntry * relations are held open with locks for the transaction duration, preventing * relcache invalidation. The entry itself is torn down at batch end by * ri_FastPathEndBatch(); on abort, ResourceOwner releases the cached - * relations and the XactCallback/SubXactCallback NULL the static cache pointer - * to prevent any subsequent access. + * relations and the XactCallback NULLs the static cache pointer to prevent + * any subsequent access. */ typedef struct RI_FastPathEntry { @@ -267,6 +267,7 @@ static dclist_head ri_constraint_cache_valid_list; static HTAB *ri_fastpath_cache = NULL; static bool ri_fastpath_callback_registered = false; +static bool ri_fastpath_flushing = false; /* * Local function prototypes @@ -469,14 +470,30 @@ RI_FKey_check(TriggerData *trigdata) */ if (ri_fastpath_is_applicable(riinfo)) { - if (AfterTriggerIsActive()) + if (AfterTriggerIsActive() && + GetCurrentTransactionNestLevel() == 1 && + !ri_fastpath_flushing) { /* Batched path: buffer and probe in groups */ ri_FastPathBatchAdd(riinfo, fk_rel, newslot); } else { - /* ALTER TABLE validation: per-row, no cache */ + /* + * Per-row path, used when batching is not safe or not applicable: + * + * - ALTER TABLE validation, where no after-trigger firing is + * active; + * + * - any FK check inside a subtransaction, since the batch cache + * is confined to the top transaction level (it cannot be cleanly + * unwound on subxact abort); + * + * - a re-entrant check from user cast/operator code running + * during a batch flush, since adding a cache entry while + * ri_FastPathEndBatch is iterating the cache could leave it + * unflushed. + */ ri_FastPathCheck(riinfo, fk_rel, newslot); } return PointerGetDatum(NULL); @@ -4181,19 +4198,41 @@ ri_FastPathEndBatch(void *arg) if (ri_fastpath_cache == NULL) return; - /* Flush any partial batches -- can throw ERROR */ - hash_seq_init(&status, ri_fastpath_cache); - while ((entry = hash_seq_search(&status)) != NULL) + /* + * Set a flag for the duration of the scan so that any FK check triggered + * by user cast or operator code during a flush takes the per-row path + * instead of adding a new entry to the cache we are iterating. A new + * entry could land in an already-scanned bucket and then be torn down + * unflushed below. + * + * The flush can throw ERROR (a reported constraint violation, or an error + * from the user code it runs). In that case ri_FastPathTeardown below is + * skipped; the ResourceOwner and the transaction-end callback handle + * resource cleanup on the abort path. The PG_FINALLY only resets the + * flag and deliberately does not attempt teardown. + */ + Assert(!ri_fastpath_flushing); + ri_fastpath_flushing = true; + PG_TRY(); { - if (entry->batch_count > 0) + hash_seq_init(&status, ri_fastpath_cache); + while ((entry = hash_seq_search(&status)) != NULL) { - Relation fk_rel = table_open(entry->fk_relid, AccessShareLock); - RI_ConstraintInfo *riinfo = ri_LoadConstraintInfo(entry->conoid); + if (entry->batch_count > 0) + { + Relation fk_rel = table_open(entry->fk_relid, AccessShareLock); + RI_ConstraintInfo *riinfo = ri_LoadConstraintInfo(entry->conoid); - ri_FastPathBatchFlush(entry, fk_rel, riinfo); - table_close(fk_rel, NoLock); + ri_FastPathBatchFlush(entry, fk_rel, riinfo); + table_close(fk_rel, NoLock); + } } } + PG_FINALLY(); + { + ri_fastpath_flushing = false; + } + PG_END_TRY(); ri_FastPathTeardown(); } @@ -4245,22 +4284,14 @@ ri_FastPathXactCallback(XactEvent event, void *arg) */ ri_fastpath_cache = NULL; ri_fastpath_callback_registered = false; -} -static void -ri_FastPathSubXactCallback(SubXactEvent event, SubTransactionId mySubid, - SubTransactionId parentSubid, void *arg) -{ - if (event == SUBXACT_EVENT_ABORT_SUB) - { - /* - * ResourceOwner already released relations. NULL the static pointers - * so the still-registered batch callback becomes a no-op for the rest - * of this transaction. - */ - ri_fastpath_cache = NULL; - ri_fastpath_callback_registered = false; - } + /* + * Also clear the in-flush flag. ri_FastPathEndBatch() already clears it + * via PG_FINALLY, so this is just defensive: it keeps a stale flag from + * surviving into the next transaction should any future path leave it + * set. + */ + ri_fastpath_flushing = false; } /* @@ -4287,7 +4318,6 @@ ri_FastPathGetEntry(const RI_ConstraintInfo *riinfo, Relation fk_rel) if (!ri_fastpath_xact_callback_registered) { RegisterXactCallback(ri_FastPathXactCallback, NULL); - RegisterSubXactCallback(ri_FastPathSubXactCallback, NULL); ri_fastpath_xact_callback_registered = true; } diff --git a/src/test/regress/expected/foreign_key.out b/src/test/regress/expected/foreign_key.out index e08dff99f03..e1563144d4c 100644 --- a/src/test/regress/expected/foreign_key.out +++ b/src/test/regress/expected/foreign_key.out @@ -3768,3 +3768,27 @@ SELECT count(*), max(a) FROM fp_reentry_fk2; -- 64 rows, max 1 (1 row) DROP TABLE fp_reentry_fk2, fp_reentry_pk2; +-- Subtransaction abort during after-trigger firing must not drop FK checks +-- for rows buffered earlier in the same statement. Batching is confined to +-- the top transaction level and the buffered batch is no longer discarded on +-- subxact abort, so the violating rows are detected. +CREATE TABLE fp_subxact_pk (id int PRIMARY KEY); +INSERT INTO fp_subxact_pk SELECT g FROM generate_series(1, 10) g; +CREATE TABLE fp_subxact_fk (a int, tag text); +ALTER TABLE fp_subxact_fk ADD CONSTRAINT fp_subxact_fk_fkey + FOREIGN KEY (a) REFERENCES fp_subxact_pk (id); +CREATE FUNCTION fp_abort_subxact() RETURNS trigger LANGUAGE plpgsql AS $$ +BEGIN + IF NEW.tag = 'boom' THEN + BEGIN PERFORM 1/0; EXCEPTION WHEN division_by_zero THEN NULL; END; + END IF; + RETURN NEW; +END$$; +CREATE TRIGGER fp_subxact_trg AFTER INSERT ON fp_subxact_fk + FOR EACH ROW EXECUTE FUNCTION fp_abort_subxact(); +INSERT INTO fp_subxact_fk VALUES (999, 'bad'), (0, 'boom'), (1, 'ok'); +ERROR: insert or update on table "fp_subxact_fk" violates foreign key constraint "fp_subxact_fk_fkey" +DETAIL: Key (a)=(999) is not present in table "fp_subxact_pk". +DROP TRIGGER fp_subxact_trg ON fp_subxact_fk; +DROP FUNCTION fp_abort_subxact(); +DROP TABLE fp_subxact_fk, fp_subxact_pk; diff --git a/src/test/regress/sql/foreign_key.sql b/src/test/regress/sql/foreign_key.sql index 87381194f41..abeb85965b9 100644 --- a/src/test/regress/sql/foreign_key.sql +++ b/src/test/regress/sql/foreign_key.sql @@ -2726,3 +2726,26 @@ BEGIN END$$; SELECT count(*), max(a) FROM fp_reentry_fk2; -- 64 rows, max 1 DROP TABLE fp_reentry_fk2, fp_reentry_pk2; + +-- Subtransaction abort during after-trigger firing must not drop FK checks +-- for rows buffered earlier in the same statement. Batching is confined to +-- the top transaction level and the buffered batch is no longer discarded on +-- subxact abort, so the violating rows are detected. +CREATE TABLE fp_subxact_pk (id int PRIMARY KEY); +INSERT INTO fp_subxact_pk SELECT g FROM generate_series(1, 10) g; +CREATE TABLE fp_subxact_fk (a int, tag text); +ALTER TABLE fp_subxact_fk ADD CONSTRAINT fp_subxact_fk_fkey + FOREIGN KEY (a) REFERENCES fp_subxact_pk (id); +CREATE FUNCTION fp_abort_subxact() RETURNS trigger LANGUAGE plpgsql AS $$ +BEGIN + IF NEW.tag = 'boom' THEN + BEGIN PERFORM 1/0; EXCEPTION WHEN division_by_zero THEN NULL; END; + END IF; + RETURN NEW; +END$$; +CREATE TRIGGER fp_subxact_trg AFTER INSERT ON fp_subxact_fk + FOR EACH ROW EXECUTE FUNCTION fp_abort_subxact(); +INSERT INTO fp_subxact_fk VALUES (999, 'bad'), (0, 'boom'), (1, 'ok'); +DROP TRIGGER fp_subxact_trg ON fp_subxact_fk; +DROP FUNCTION fp_abort_subxact(); +DROP TABLE fp_subxact_fk, fp_subxact_pk; -- 2.47.3
From 9a078d0f332f96d8e16040558ddb22daaf199778 Mon Sep 17 00:00:00 2001 From: Amit Langote <[email protected]> Date: Wed, 10 Jun 2026 21:07:09 +0900 Subject: [PATCH v3 1/2] Fix out-of-bounds write in RI fast-path batch on re-entry The FK fast-path batching added in b7b27eb41a5 wrote the incoming row into the batch array before checking whether the array was full: fpentry->batch[fpentry->batch_count] = ExecCopySlotHeapTuple(newslot); fpentry->batch_count++; if (fpentry->batch_count >= RI_FASTPATH_BATCH_SIZE) ri_FastPathBatchFlush(fpentry, fk_rel, riinfo); batch_count is reset to zero only at the end of ri_FastPathBatchFlush(), so it remains at RI_FASTPATH_BATCH_SIZE throughout a full-batch flush. A flush runs user-defined cast functions and equality operators; if that user code performs DML on the same FK table, ri_FastPathBatchAdd() re-enters with batch_count == RI_FASTPATH_BATCH_SIZE and writes one past the end of the array, corrupting the adjacent batch_count field. This is reachable by an unprivileged table owner via an implicit cast with a PL/pgSQL function and causes a SIGSEGV in assert-enabled builds. Fix by bounds-checking the write into the batch array so a re-entrant add can never write past the end, and by adding a "flushing" flag to RI_FastPathEntry that routes re-entrant ri_FastPathBatchAdd() calls on a busy entry to the per-row path (ri_FastPathCheck) instead of touching the mid-flush batch array. The flag is set around the probe in ri_FastPathBatchFlush() and cleared in a PG_FINALLY, which also resets batch_count, so the entry is left empty and reusable if a flush error (including a reported FK violation) is caught by a savepoint. Add regression tests for both the re-entrant flush and reuse of an entry after a flush error caught by a savepoint. Reported-by: Nikolay Samokhvalov <[email protected]> Reviewed-by: Nikolay Samokhvalov <[email protected]> Reviewed-by: Ayush Tiwari <[email protected]> Discussion: https://postgr.es/m/CAM527d9exRCdWrhJOnAxk_vACg7sr_yPoaJp_+uCFY0qP8v=aw@mail.gmail.com --- src/backend/utils/adt/ri_triggers.c | 80 ++++++++++++++++++----- src/test/regress/expected/foreign_key.out | 56 ++++++++++++++++ src/test/regress/sql/foreign_key.sql | 46 +++++++++++++ 3 files changed, 165 insertions(+), 17 deletions(-) diff --git a/src/backend/utils/adt/ri_triggers.c b/src/backend/utils/adt/ri_triggers.c index dc89c686394..917a544c32b 100644 --- a/src/backend/utils/adt/ri_triggers.c +++ b/src/backend/utils/adt/ri_triggers.c @@ -249,6 +249,12 @@ typedef struct RI_FastPathEntry */ HeapTuple batch[RI_FASTPATH_BATCH_SIZE]; int batch_count; + + /* + * true while this entry's batch is being flushed; guards against + * re-entrant ri_FastPathBatchAdd from user code run during the flush. + */ + bool flushing; } RI_FastPathEntry; /* @@ -2860,15 +2866,38 @@ ri_FastPathBatchAdd(RI_ConstraintInfo *riinfo, Relation fk_rel, TupleTableSlot *newslot) { RI_FastPathEntry *fpentry = ri_FastPathGetEntry(riinfo, fk_rel); - MemoryContext oldcxt; - oldcxt = MemoryContextSwitchTo(fpentry->flush_cxt); - fpentry->batch[fpentry->batch_count] = - ExecCopySlotHeapTuple(newslot); - fpentry->batch_count++; - MemoryContextSwitchTo(oldcxt); + /* + * If this entry is already being flushed, a cast function or an operator + * invoked during the flush has re-entered with DML on the same FK. Fall + * back to the per-row path rather than touching the batch array, which is + * mid-flush. + */ + if (unlikely(fpentry->flushing)) + { + ri_FastPathCheck(riinfo, fk_rel, newslot); + return; + } + + /* + * Buffer the row. A full batch is flushed below and re-entry is handled + * above, so there is always room here; the bounds check just guards the + * array write. + */ + if (fpentry->batch_count < RI_FASTPATH_BATCH_SIZE) + { + MemoryContext oldcxt = MemoryContextSwitchTo(fpentry->flush_cxt); - if (fpentry->batch_count >= RI_FASTPATH_BATCH_SIZE) + fpentry->batch[fpentry->batch_count] = + ExecCopySlotHeapTuple(newslot); + fpentry->batch_count++; + MemoryContextSwitchTo(oldcxt); + } + else + elog(ERROR, "RI fast-path batch unexpectedly full"); + + /* Flush as soon as the batch is full. */ + if (fpentry->batch_count == RI_FASTPATH_BATCH_SIZE) ri_FastPathBatchFlush(fpentry, fk_rel, riinfo); } @@ -2944,13 +2973,30 @@ ri_FastPathBatchFlush(RI_FastPathEntry *fpentry, Relation fk_rel, } Assert(riinfo->fpmeta); - /* Skip array overhead for single-row batches. */ - if (riinfo->nkeys == 1 && fpentry->batch_count > 1) - violation_index = ri_FastPathFlushArray(fpentry, fk_slot, riinfo, - fk_rel, snapshot, scandesc); - else - violation_index = ri_FastPathFlushLoop(fpentry, fk_slot, riinfo, - fk_rel, snapshot, scandesc); + /* + * The probe runs user-defined cast and equality functions. Set the + * flushing flag around it so a re-entrant ri_FastPathBatchAdd on this + * entry takes the per-row path, and clear it even on error so the entry + * is reusable if the error is caught by a savepoint. + */ + Assert(!fpentry->flushing); + fpentry->flushing = true; + PG_TRY(); + { + /* Skip array overhead for single-row batches. */ + if (riinfo->nkeys == 1 && fpentry->batch_count > 1) + violation_index = ri_FastPathFlushArray(fpentry, fk_slot, riinfo, + fk_rel, snapshot, scandesc); + else + violation_index = ri_FastPathFlushLoop(fpentry, fk_slot, riinfo, + fk_rel, snapshot, scandesc); + } + PG_FINALLY(); + { + fpentry->flushing = false; + fpentry->batch_count = 0; + } + PG_END_TRY(); SetUserIdAndSecContext(saved_userid, saved_sec_context); UnregisterSnapshot(snapshot); @@ -2966,9 +3012,6 @@ ri_FastPathBatchFlush(RI_FastPathEntry *fpentry, Relation fk_rel, MemoryContextReset(fpentry->flush_cxt); MemoryContextSwitchTo(oldcxt); - - /* Reset. */ - fpentry->batch_count = 0; } /* @@ -4307,6 +4350,9 @@ ri_FastPathGetEntry(const RI_ConstraintInfo *riinfo, Relation fk_rel) RegisterAfterTriggerBatchCallback(ri_FastPathEndBatch, NULL); ri_fastpath_callback_registered = true; } + + entry->flushing = false; + entry->batch_count = 0; } return entry; diff --git a/src/test/regress/expected/foreign_key.out b/src/test/regress/expected/foreign_key.out index 8b3b268de0f..e08dff99f03 100644 --- a/src/test/regress/expected/foreign_key.out +++ b/src/test/regress/expected/foreign_key.out @@ -3712,3 +3712,59 @@ INSERT INTO fp_pk_dup VALUES (1); CREATE TABLE fp_fk_dup (a int REFERENCES fp_pk_dup); INSERT INTO fp_fk_dup SELECT 1 FROM generate_series(1, 100); DROP TABLE fp_fk_dup, fp_pk_dup; +-- Re-entrant FK fast-path: DML on the same FK table from a cast function +-- during a full-batch flush must not corrupt the batch array. +CREATE TABLE fp_reentry_pk (id int PRIMARY KEY); +INSERT INTO fp_reentry_pk VALUES (1), (2); +CREATE TYPE fp_vch AS (v int); +CREATE FUNCTION fp_vcast(fp_vch) RETURNS int LANGUAGE plpgsql AS $$ +BEGIN + IF $1.v = 1 THEN + INSERT INTO fp_reentry_fk VALUES (row(2)::fp_vch); + END IF; + RETURN $1.v; +END$$; +CREATE CAST (fp_vch AS int) WITH FUNCTION fp_vcast(fp_vch) AS IMPLICIT; +CREATE TABLE fp_reentry_fk (a fp_vch + REFERENCES fp_reentry_pk (id)); +-- Fill exactly one batch so the flush fires; the cast re-enters with DML +-- on the same FK and must take the per-row path. +INSERT INTO fp_reentry_fk SELECT row(1)::fp_vch FROM generate_series(1, 64); +SELECT a, count(*) FROM fp_reentry_fk GROUP BY a ORDER BY a; + a | count +-----+------- + (1) | 64 + (2) | 64 +(2 rows) + +DROP TABLE fp_reentry_fk, fp_reentry_pk; +DROP CAST (fp_vch AS int); +DROP FUNCTION fp_vcast(fp_vch); +DROP TYPE fp_vch; +-- Flush error caught by a savepoint must leave the entry empty and reusable. +CREATE TABLE fp_reentry_pk2 (id int PRIMARY KEY); +INSERT INTO fp_reentry_pk2 VALUES (1); +CREATE TABLE fp_reentry_fk2 (a int REFERENCES fp_reentry_pk2 (id)); +DO $$ +BEGIN + -- A batch containing a violating row; the flush reports the violation. + BEGIN + INSERT INTO fp_reentry_fk2 SELECT CASE WHEN g = 32 THEN 999 ELSE 1 END + FROM generate_series(1, 64) g; + EXCEPTION WHEN foreign_key_violation THEN + RAISE NOTICE 'caught fk violation'; + END; + + -- Reuse the same FK with a full batch in the same transaction. The + -- entry must be empty after the caught violation: no stale rows from the + -- rolled-back batch (in particular no 999), and no array overflow. + INSERT INTO fp_reentry_fk2 SELECT 1 FROM generate_series(1, 64); +END$$; +NOTICE: caught fk violation +SELECT count(*), max(a) FROM fp_reentry_fk2; -- 64 rows, max 1 + count | max +-------+----- + 64 | 1 +(1 row) + +DROP TABLE fp_reentry_fk2, fp_reentry_pk2; diff --git a/src/test/regress/sql/foreign_key.sql b/src/test/regress/sql/foreign_key.sql index 7eb86b188f0..87381194f41 100644 --- a/src/test/regress/sql/foreign_key.sql +++ b/src/test/regress/sql/foreign_key.sql @@ -2680,3 +2680,49 @@ INSERT INTO fp_pk_dup VALUES (1); CREATE TABLE fp_fk_dup (a int REFERENCES fp_pk_dup); INSERT INTO fp_fk_dup SELECT 1 FROM generate_series(1, 100); DROP TABLE fp_fk_dup, fp_pk_dup; + +-- Re-entrant FK fast-path: DML on the same FK table from a cast function +-- during a full-batch flush must not corrupt the batch array. +CREATE TABLE fp_reentry_pk (id int PRIMARY KEY); +INSERT INTO fp_reentry_pk VALUES (1), (2); +CREATE TYPE fp_vch AS (v int); +CREATE FUNCTION fp_vcast(fp_vch) RETURNS int LANGUAGE plpgsql AS $$ +BEGIN + IF $1.v = 1 THEN + INSERT INTO fp_reentry_fk VALUES (row(2)::fp_vch); + END IF; + RETURN $1.v; +END$$; +CREATE CAST (fp_vch AS int) WITH FUNCTION fp_vcast(fp_vch) AS IMPLICIT; +CREATE TABLE fp_reentry_fk (a fp_vch + REFERENCES fp_reentry_pk (id)); +-- Fill exactly one batch so the flush fires; the cast re-enters with DML +-- on the same FK and must take the per-row path. +INSERT INTO fp_reentry_fk SELECT row(1)::fp_vch FROM generate_series(1, 64); +SELECT a, count(*) FROM fp_reentry_fk GROUP BY a ORDER BY a; +DROP TABLE fp_reentry_fk, fp_reentry_pk; +DROP CAST (fp_vch AS int); +DROP FUNCTION fp_vcast(fp_vch); +DROP TYPE fp_vch; + +-- Flush error caught by a savepoint must leave the entry empty and reusable. +CREATE TABLE fp_reentry_pk2 (id int PRIMARY KEY); +INSERT INTO fp_reentry_pk2 VALUES (1); +CREATE TABLE fp_reentry_fk2 (a int REFERENCES fp_reentry_pk2 (id)); +DO $$ +BEGIN + -- A batch containing a violating row; the flush reports the violation. + BEGIN + INSERT INTO fp_reentry_fk2 SELECT CASE WHEN g = 32 THEN 999 ELSE 1 END + FROM generate_series(1, 64) g; + EXCEPTION WHEN foreign_key_violation THEN + RAISE NOTICE 'caught fk violation'; + END; + + -- Reuse the same FK with a full batch in the same transaction. The + -- entry must be empty after the caught violation: no stale rows from the + -- rolled-back batch (in particular no 999), and no array overflow. + INSERT INTO fp_reentry_fk2 SELECT 1 FROM generate_series(1, 64); +END$$; +SELECT count(*), max(a) FROM fp_reentry_fk2; -- 64 rows, max 1 +DROP TABLE fp_reentry_fk2, fp_reentry_pk2; -- 2.47.3
