Fix incorrect optimization of foreign-key checks. When an UPDATE on the

referencing table does not change the tuple's FK column(s), we don't bother
to check the PK table since the constraint was presumably already valid.
However, the check is still necessary if the tuple was inserted by our own
transaction, since in that case the INSERT trigger will conclude it need not
make the check (since its version of the tuple has been deleted).  We got this
right for simple cases, but not when the insert and update are in different
subtransactions of the current top-level transaction; in such cases the FK
check would never be made at all.  (Hence, problem dates back to 8.0 when
subtransactions were added --- it's actually the subtransaction version of a
bug fixed in 7.3.5.)  Fix, and add regression test cases.  Report and fix by
Affan Salman.

diff --git a/src/backend/commands/trigger.c b/src/backend/commands/trigger.c
index 3f251ad6dd59d79e206ca205575f3c7f9b40b184..80b28f5e4b40f1cc465bb3c91898504a9cc23ab9 100644 (file)
--- a/src/backend/commands/trigger.c
+++ b/src/backend/commands/trigger.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.215 2007/07/01 17:45:42 tgl Exp $
+ *   $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.216 2007/07/17 17:45:28 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -3396,8 +3396,7 @@ AfterTriggerSaveEvent(ResultRelInfo *relinfo, int event, bool row_trigger,
                     * anything, so we have to do the check for the UPDATE
                     * anyway.
                     */
-                   if (HeapTupleHeaderGetXmin(oldtup->t_data) !=
-                       GetCurrentTransactionId() &&
+                   if (!TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(oldtup->t_data)) &&
                        RI_FKey_keyequal_upd_fk(trigger, rel, oldtup, newtup))
                    {
                        continue;

diff --git a/src/test/regress/expected/foreign_key.out b/src/test/regress/expected/foreign_key.out
index 3c0dd7f0872df01829d8e5a518c98e4b822a6ff1..56411f06a35fa7522df813198665278fd98c9dbf 100644 (file)
--- a/src/test/regress/expected/foreign_key.out
+++ b/src/test/regress/expected/foreign_key.out
@@ -1193,3 +1193,40 @@ UPDATE fktable SET id = id + 1;
 COMMIT;
 ERROR:  insert or update on table "fktable" violates foreign key constraint "fktable_fk_fkey"
 DETAIL:  Key (fk)=(20) is not present in table "pktable".
+-- check same case when insert is in a different subtransaction than update
+BEGIN;
+-- doesn't match PK, but no error yet
+INSERT INTO fktable VALUES (0, 20);
+-- UPDATE will be in a subxact
+SAVEPOINT savept1;
+-- don't change FK
+UPDATE fktable SET id = id + 1;
+-- should catch error from initial INSERT
+COMMIT;
+ERROR:  insert or update on table "fktable" violates foreign key constraint "fktable_fk_fkey"
+DETAIL:  Key (fk)=(20) is not present in table "pktable".
+BEGIN;
+-- INSERT will be in a subxact
+SAVEPOINT savept1;
+-- doesn't match PK, but no error yet
+INSERT INTO fktable VALUES (0, 20);
+RELEASE SAVEPOINT savept1;
+-- don't change FK
+UPDATE fktable SET id = id + 1;
+-- should catch error from initial INSERT
+COMMIT;
+ERROR:  insert or update on table "fktable" violates foreign key constraint "fktable_fk_fkey"
+DETAIL:  Key (fk)=(20) is not present in table "pktable".
+BEGIN;
+-- doesn't match PK, but no error yet
+INSERT INTO fktable VALUES (0, 20);
+-- UPDATE will be in a subxact
+SAVEPOINT savept1;
+-- don't change FK
+UPDATE fktable SET id = id + 1;
+-- Roll back the UPDATE
+ROLLBACK TO savept1;
+-- should catch error from initial INSERT
+COMMIT;
+ERROR:  insert or update on table "fktable" violates foreign key constraint "fktable_fk_fkey"
+DETAIL:  Key (fk)=(20) is not present in table "pktable".

diff --git a/src/test/regress/sql/foreign_key.sql b/src/test/regress/sql/foreign_key.sql
index 5a0140c280ea969c0f376133438b4eedab1e0019..1ab557b9bf30d31fa5ce48dffd9945e2dd34f377 100644 (file)
--- a/src/test/regress/sql/foreign_key.sql
+++ b/src/test/regress/sql/foreign_key.sql
@@ -830,3 +830,52 @@ UPDATE fktable SET id = id + 1;
 
 -- should catch error from initial INSERT
 COMMIT;
+
+-- check same case when insert is in a different subtransaction than update
+
+BEGIN;
+
+-- doesn't match PK, but no error yet
+INSERT INTO fktable VALUES (0, 20);
+
+-- UPDATE will be in a subxact
+SAVEPOINT savept1;
+
+-- don't change FK
+UPDATE fktable SET id = id + 1;
+
+-- should catch error from initial INSERT
+COMMIT;
+
+BEGIN;
+
+-- INSERT will be in a subxact
+SAVEPOINT savept1;
+
+-- doesn't match PK, but no error yet
+INSERT INTO fktable VALUES (0, 20);
+
+RELEASE SAVEPOINT savept1;
+
+-- don't change FK
+UPDATE fktable SET id = id + 1;
+
+-- should catch error from initial INSERT
+COMMIT;
+
+BEGIN;
+
+-- doesn't match PK, but no error yet
+INSERT INTO fktable VALUES (0, 20);
+
+-- UPDATE will be in a subxact
+SAVEPOINT savept1;
+
+-- don't change FK
+UPDATE fktable SET id = id + 1;
+
+-- Roll back the UPDATE
+ROLLBACK TO savept1;
+
+-- should catch error from initial INSERT
+COMMIT;