diff --git a/src/backend/commands/trigger.c b/src/backend/commands/trigger.c
index 57fcfbeefd94baf9e06b9d6764d46f3869cc7976..834b694ec6b872081855f009a3919ea2ab5c1b8a 100644
--- a/src/backend/commands/trigger.c
+++ b/src/backend/commands/trigger.c
@@ -4582,39 +4582,30 @@ AfterTriggerSaveEvent(EState *estate, ResultRelInfo *relinfo,
continue;
/*
- * If this is an UPDATE of a PK table or FK table that does not change
- * the PK or FK respectively, we can skip queuing the event: there is
- * no need to fire the trigger.
+ * If the trigger is a foreign key enforcement trigger, there are
+ * certain cases where we can skip queueing the event because we can
+ * tell by inspection that the FK constraint will still pass.
*/
if (TRIGGER_FIRED_BY_UPDATE(event))
{
switch (RI_FKey_trigger_type(trigger->tgfoid))
{
case RI_TRIGGER_PK:
- /* Update on PK table */
- if (RI_FKey_keyequal_upd_pk(trigger, rel, oldtup, newtup))
+ /* Update on trigger's PK table */
+ if (!RI_FKey_pk_upd_check_required(trigger, rel,
+ oldtup, newtup))
{
- /* key unchanged, so skip queuing this event */
+ /* skip queuing this event */
continue;
}
break;
case RI_TRIGGER_FK:
-
- /*
- * Update on FK table
- *
- * There is one exception when updating FK tables: if the
- * updated row was inserted by our own transaction and the
- * FK is deferred, we still need to fire the trigger. This
- * is because our UPDATE will invalidate the INSERT so the
- * end-of-transaction INSERT RI trigger will not do
- * anything, so we have to do the check for the UPDATE
- * anyway.
- */
- if (!TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(oldtup->t_data)) &&
- RI_FKey_keyequal_upd_fk(trigger, rel, oldtup, newtup))
+ /* Update on trigger's FK table */
+ if (!RI_FKey_fk_upd_check_required(trigger, rel,
+ oldtup, newtup))
{
+ /* skip queuing this event */
continue;
}
break;
diff --git a/src/backend/utils/adt/ri_triggers.c b/src/backend/utils/adt/ri_triggers.c
index f83f20be7abd56d89df41409ca4ffc425f0dd922..d61d1e0b3658b25cf7cebe740f23e1c64b44606d 100644
--- a/src/backend/utils/adt/ri_triggers.c
+++ b/src/backend/utils/adt/ri_triggers.c
@@ -1928,7 +1928,7 @@ RI_FKey_setdefault_del(PG_FUNCTION_ARGS)
* If we just deleted the PK row whose key was equal to the FK
* columns' default values, and a referencing row exists in the FK
* table, we would have updated that row to the same values it
- * already had --- and RI_FKey_keyequal_upd_fk would therefore
+ * already had --- and RI_FKey_fk_upd_check_required would hence
* believe no check is necessary. So we need to do another lookup
* now and in case a reference still exists, abort the operation.
* That is already implemented in the NO ACTION trigger, so just
@@ -2125,7 +2125,7 @@ RI_FKey_setdefault_upd(PG_FUNCTION_ARGS)
* If we just updated the PK row whose key was equal to the FK
* columns' default values, and a referencing row exists in the FK
* table, we would have updated that row to the same values it
- * already had --- and RI_FKey_keyequal_upd_fk would therefore
+ * already had --- and RI_FKey_fk_upd_check_required would hence
* believe no check is necessary. So we need to do another lookup
* now and in case a reference still exists, abort the operation.
* That is already implemented in the NO ACTION trigger, so just
@@ -2158,16 +2158,18 @@ RI_FKey_setdefault_upd(PG_FUNCTION_ARGS)
/* ----------
- * RI_FKey_keyequal_upd_pk -
+ * RI_FKey_pk_upd_check_required -
*
- * Check if we have a key change on an update to a PK relation. This is
- * used by the AFTER trigger queue manager to see if it can skip queuing
- * an instance of an RI trigger.
+ * Check if we really need to fire the RI trigger for an update to a PK
+ * relation. This is called by the AFTER trigger queue manager to see if
+ * it can skip queuing an instance of an RI trigger. Returns TRUE if the
+ * trigger must be fired, FALSE if we can prove the constraint will still
+ * be satisfied.
* ----------
*/
bool
-RI_FKey_keyequal_upd_pk(Trigger *trigger, Relation pk_rel,
- HeapTuple old_row, HeapTuple new_row)
+RI_FKey_pk_upd_check_required(Trigger *trigger, Relation pk_rel,
+ HeapTuple old_row, HeapTuple new_row)
{
RI_ConstraintInfo riinfo;
@@ -2177,19 +2179,32 @@ RI_FKey_keyequal_upd_pk(Trigger *trigger, Relation pk_rel,
ri_FetchConstraintInfo(&riinfo, trigger, pk_rel, true);
/*
- * Nothing to do if no column names to compare given
+ * Nothing to do if no columns (satisfaction of such a constraint only
+ * requires existence of a PK row, and this update won't change that).
*/
if (riinfo.nkeys == 0)
- return true;
+ return false;
switch (riinfo.confmatchtype)
{
case FKCONSTR_MATCH_SIMPLE:
case FKCONSTR_MATCH_FULL:
- /* Return true if keys are equal */
- return ri_KeysEqual(pk_rel, old_row, new_row, &riinfo, true);
- /* Handle MATCH PARTIAL set null delete. */
+ /*
+ * If any old key value is NULL, the row could not have been
+ * referenced by an FK row, so no check is needed.
+ */
+ if (ri_NullCheck(old_row, &riinfo, true) != RI_KEYS_NONE_NULL)
+ return false;
+
+ /* If all old and new key values are equal, no check is needed */
+ if (ri_KeysEqual(pk_rel, old_row, new_row, &riinfo, true))
+ return false;
+
+ /* Else we need to fire the trigger. */
+ return true;
+
+ /* Handle MATCH PARTIAL check. */
case FKCONSTR_MATCH_PARTIAL:
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
@@ -2207,16 +2222,18 @@ RI_FKey_keyequal_upd_pk(Trigger *trigger, Relation pk_rel,
}
/* ----------
- * RI_FKey_keyequal_upd_fk -
+ * RI_FKey_fk_upd_check_required -
*
- * Check if we have a key change on an update to an FK relation. This is
- * used by the AFTER trigger queue manager to see if it can skip queuing
- * an instance of an RI trigger.
+ * Check if we really need to fire the RI trigger for an update to an FK
+ * relation. This is called by the AFTER trigger queue manager to see if
+ * it can skip queuing an instance of an RI trigger. Returns TRUE if the
+ * trigger must be fired, FALSE if we can prove the constraint will still
+ * be satisfied.
* ----------
*/
bool
-RI_FKey_keyequal_upd_fk(Trigger *trigger, Relation fk_rel,
- HeapTuple old_row, HeapTuple new_row)
+RI_FKey_fk_upd_check_required(Trigger *trigger, Relation fk_rel,
+ HeapTuple old_row, HeapTuple new_row)
{
RI_ConstraintInfo riinfo;
@@ -2226,19 +2243,78 @@ RI_FKey_keyequal_upd_fk(Trigger *trigger, Relation fk_rel,
ri_FetchConstraintInfo(&riinfo, trigger, fk_rel, false);
/*
- * Nothing to do if no column names to compare given
+ * Nothing to do if no columns (satisfaction of such a constraint only
+ * requires existence of a PK row, and this update won't change that).
*/
if (riinfo.nkeys == 0)
- return true;
+ return false;
switch (riinfo.confmatchtype)
{
case FKCONSTR_MATCH_SIMPLE:
+ /*
+ * If any new key value is NULL, the row must satisfy the
+ * constraint, so no check is needed.
+ */
+ if (ri_NullCheck(new_row, &riinfo, false) != RI_KEYS_NONE_NULL)
+ return false;
+
+ /*
+ * If the original row was inserted by our own transaction, we
+ * must fire the trigger whether or not the keys are equal. This
+ * is because our UPDATE will invalidate the INSERT so that the
+ * INSERT RI trigger will not do anything; so we had better do the
+ * UPDATE check. (We could skip this if we knew the INSERT
+ * trigger already fired, but there is no easy way to know that.)
+ */
+ if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(old_row->t_data)))
+ return true;
+
+ /* If all old and new key values are equal, no check is needed */
+ if (ri_KeysEqual(fk_rel, old_row, new_row, &riinfo, false))
+ return false;
+
+ /* Else we need to fire the trigger. */
+ return true;
+
case FKCONSTR_MATCH_FULL:
- /* Return true if keys are equal */
- return ri_KeysEqual(fk_rel, old_row, new_row, &riinfo, false);
+ /*
+ * If all new key values are NULL, the row must satisfy the
+ * constraint, so no check is needed. On the other hand, if only
+ * some of them are NULL, the row must fail the constraint. We
+ * must not throw error here, because the row might get
+ * invalidated before the constraint is to be checked, but we
+ * should queue the event to apply the check later.
+ */
+ switch (ri_NullCheck(new_row, &riinfo, false))
+ {
+ case RI_KEYS_ALL_NULL:
+ return false;
+ case RI_KEYS_SOME_NULL:
+ return true;
+ case RI_KEYS_NONE_NULL:
+ break; /* continue with the check */
+ }
+
+ /*
+ * If the original row was inserted by our own transaction, we
+ * must fire the trigger whether or not the keys are equal. This
+ * is because our UPDATE will invalidate the INSERT so that the
+ * INSERT RI trigger will not do anything; so we had better do the
+ * UPDATE check. (We could skip this if we knew the INSERT
+ * trigger already fired, but there is no easy way to know that.)
+ */
+ if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(old_row->t_data)))
+ return true;
- /* Handle MATCH PARTIAL set null delete. */
+ /* If all old and new key values are equal, no check is needed */
+ if (ri_KeysEqual(fk_rel, old_row, new_row, &riinfo, false))
+ return false;
+
+ /* Else we need to fire the trigger. */
+ return true;
+
+ /* Handle MATCH PARTIAL check. */
case FKCONSTR_MATCH_PARTIAL:
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
@@ -3376,6 +3452,11 @@ ri_HashPreparedPlan(RI_QueryKey *key, SPIPlanPtr plan)
* ri_KeysEqual -
*
* Check if all key values in OLD and NEW are equal.
+ *
+ * Note: at some point we might wish to redefine this as checking for
+ * "IS NOT DISTINCT" rather than "=", that is, allow two nulls to be
+ * considered equal. Currently there is no need since all callers have
+ * previously found at least one of the rows to contain no nulls.
* ----------
*/
static bool
diff --git a/src/include/commands/trigger.h b/src/include/commands/trigger.h
index 93033414d914131ef3357f23cb8aecd7ed643b30..e790b9d3009bf9e3eb11f8cc8643b8860669150c 100644
--- a/src/include/commands/trigger.h
+++ b/src/include/commands/trigger.h
@@ -191,10 +191,10 @@ extern bool AfterTriggerPendingOnRel(Oid relid);
/*
* in utils/adt/ri_triggers.c
*/
-extern bool RI_FKey_keyequal_upd_pk(Trigger *trigger, Relation pk_rel,
- HeapTuple old_row, HeapTuple new_row);
-extern bool RI_FKey_keyequal_upd_fk(Trigger *trigger, Relation fk_rel,
- HeapTuple old_row, HeapTuple new_row);
+extern bool RI_FKey_pk_upd_check_required(Trigger *trigger, Relation pk_rel,
+ HeapTuple old_row, HeapTuple new_row);
+extern bool RI_FKey_fk_upd_check_required(Trigger *trigger, Relation fk_rel,
+ HeapTuple old_row, HeapTuple new_row);
extern bool RI_Initial_Check(Trigger *trigger,
Relation fk_rel, Relation pk_rel);