Add support for NOT ENFORCED in foreign key constraints

This expands the NOT ENFORCED constraint flag, previously only
supported for CHECK constraints (commit ca87c415e2), to foreign key
constraints.

Normally, when a foreign key constraint is created on a table, action
and check triggers are added to maintain data integrity.  With this
patch, if a constraint is marked as NOT ENFORCED, integrity checks are
no longer required, making these triggers unnecessary.  Consequently,
when creating a NOT ENFORCED foreign key constraint, triggers will not
be created, and the constraint will be marked as NOT VALID.
Similarly, if an existing foreign key constraint is changed to NOT
ENFORCED, the associated triggers will be dropped, and the constraint
will also be marked as NOT VALID.  Conversely, if a NOT ENFORCED
foreign key constraint is changed to ENFORCED, the necessary triggers
will be created, and the will be changed to VALID by performing
necessary validation.

Since not-enforced foreign key constraints have no triggers, the
shortcut used for example in psql and pg_dump to skip looking for
foreign keys if the relation is known not to have triggers no longer
applies.  (It already didn't work for partitioned tables.)

Author: Amul Sul <sulamul@gmail.com>
Reviewed-by: Joel Jacobson <joel@compiler.org>
Reviewed-by: Andrew Dunstan <andrew@dunslane.net>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: jian he <jian.universality@gmail.com>
Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org>
Reviewed-by: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Reviewed-by: Isaac Morland <isaac.morland@gmail.com>
Reviewed-by: Alexandra Wang <alexandra.wang.oss@gmail.com>
Tested-by: Triveni N <triveni.n@enterprisedb.com>
Discussion: https://www.postgresql.org/message-id/flat/CAAJ_b962c5AcYW9KUt_R_ER5qs3fUGbe4az-SP-vuwPS-w-AGA@mail.gmail.com

doc/src/sgml/catalogs.sgml

@@ -2620,7 +2620,6 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
       </para>
       <para>
        Is the constraint enforced?
-       Currently, can be false only for CHECK constraints
       </para></entry>
      </row>
 

doc/src/sgml/ref/alter_table.sgml

@@ -58,7 +58,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
-    ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
+    ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ] [ ENFORCED | NOT ENFORCED ]
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ INHERIT | NO INHERIT ]
     VALIDATE CONSTRAINT <replaceable class="parameter">constraint_name</replaceable>
     DROP CONSTRAINT [ IF EXISTS ]  <replaceable class="parameter">constraint_name</replaceable> [ RESTRICT | CASCADE ]
@@ -589,7 +589,8 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
       This form validates a foreign key or check constraint that was
       previously created as <literal>NOT VALID</literal>, by scanning the
       table to ensure there are no rows for which the constraint is not
-      satisfied.  Nothing happens if the constraint is already marked valid.
+      satisfied.  If the constraint is not enforced, an error is thrown.
+      Nothing happens if the constraint is already marked valid.
       (See <xref linkend="sql-altertable-notes"/> below for an explanation
       of the usefulness of this command.)
      </para>

doc/src/sgml/ref/create_table.sgml

@@ -1409,7 +1409,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
      </para>
 
      <para>
-      This is currently only supported for <literal>CHECK</literal>
+      This is currently only supported for foreign key and <literal>CHECK</literal>
       constraints.
      </para>
     </listitem>

src/backend/catalog/pg_constraint.c

@@ -100,8 +100,9 @@ CreateConstraintEntry(const char *constraintName,
 	ObjectAddresses *addrs_auto;
 	ObjectAddresses *addrs_normal;
 
-	/* Only CHECK constraint can be not enforced */
-	Assert(isEnforced || constraintType == CONSTRAINT_CHECK);
+	/* Only CHECK or FOREIGN KEY constraint can be not enforced */
+	Assert(isEnforced || constraintType == CONSTRAINT_CHECK ||
+		   constraintType == CONSTRAINT_FOREIGN);
 	/* NOT ENFORCED constraint must be NOT VALID */
 	Assert(isEnforced || !isValidated);
 

src/backend/catalog/sql_features.txt

@@ -281,7 +281,7 @@ F461	Named character sets			NO
 F471	Scalar subquery values			YES	
 F481	Expanded NULL predicate			YES	
 F491	Constraint management			YES	
-F492	Optional table constraint enforcement			NO	check constraints only
+F492	Optional table constraint enforcement			YES	except not-null constraints
 F501	Features and conformance views			YES	
 F501	Features and conformance views	01	SQL_FEATURES view	YES	
 F501	Features and conformance views	02	SQL_SIZING view	YES	

src/backend/commands/tablecmds.c

@@ -395,6 +395,14 @@ static ObjectAddress ATExecAlterConstraint(List **wqueue, Relation rel,
 static bool ATExecAlterConstraintInternal(List **wqueue, ATAlterConstraint *cmdcon, Relation conrel,
 										  Relation tgrel, Relation rel, HeapTuple contuple,
 										  bool recurse, LOCKMODE lockmode);
+static bool ATExecAlterConstrEnforceability(List **wqueue, ATAlterConstraint *cmdcon,
+											Relation conrel, Relation tgrel,
+											const Oid fkrelid, const Oid pkrelid,
+											HeapTuple contuple, LOCKMODE lockmode,
+											Oid ReferencedParentDelTrigger,
+											Oid ReferencedParentUpdTrigger,
+											Oid ReferencingParentInsTrigger,
+											Oid ReferencingParentUpdTrigger);
 static bool ATExecAlterConstrDeferrability(List **wqueue, ATAlterConstraint *cmdcon,
 										   Relation conrel, Relation tgrel, Relation rel,
 										   HeapTuple contuple, bool recurse,
@@ -405,6 +413,14 @@ static bool ATExecAlterConstrInheritability(List **wqueue, ATAlterConstraint *cm
 static void AlterConstrTriggerDeferrability(Oid conoid, Relation tgrel, Relation rel,
 											bool deferrable, bool initdeferred,
 											List **otherrelids);
+static void AlterConstrEnforceabilityRecurse(List **wqueue, ATAlterConstraint *cmdcon,
+											 Relation conrel, Relation tgrel,
+											 const Oid fkrelid, const Oid pkrelid,
+											 HeapTuple contuple, LOCKMODE lockmode,
+											 Oid ReferencedParentDelTrigger,
+											 Oid ReferencedParentUpdTrigger,
+											 Oid ReferencingParentInsTrigger,
+											 Oid ReferencingParentUpdTrigger);
 static void AlterConstrDeferrabilityRecurse(List **wqueue, ATAlterConstraint *cmdcon,
 											Relation conrel, Relation tgrel, Relation rel,
 											HeapTuple contuple, bool recurse,
@@ -10610,7 +10626,7 @@ addFkConstraint(addFkConstraintSides fkside,
 									  CONSTRAINT_FOREIGN,
 									  fkconstraint->deferrable,
 									  fkconstraint->initdeferred,
-									  true, /* Is Enforced */
+									  fkconstraint->is_enforced,
 									  fkconstraint->initially_valid,
 									  parentConstr,
 									  RelationGetRelid(rel),
@@ -10728,21 +10744,23 @@ addFkRecurseReferenced(Constraint *fkconstraint, Relation rel,
 					   Oid parentDelTrigger, Oid parentUpdTrigger,
 					   bool with_period)
 {
-	Oid			deleteTriggerOid,
-				updateTriggerOid;
+	Oid			deleteTriggerOid = InvalidOid,
+				updateTriggerOid = InvalidOid;
 
 	Assert(CheckRelationLockedByMe(pkrel, ShareRowExclusiveLock, true));
 	Assert(CheckRelationLockedByMe(rel, ShareRowExclusiveLock, true));
 
 	/*
-	 * Create the action triggers that enforce the constraint.
+	 * Create action triggers to enforce the constraint, or skip them if the
+	 * constraint is NOT ENFORCED.
 	 */
-	createForeignKeyActionTriggers(RelationGetRelid(rel),
-								   RelationGetRelid(pkrel),
-								   fkconstraint,
-								   parentConstr, indexOid,
-								   parentDelTrigger, parentUpdTrigger,
-								   &deleteTriggerOid, &updateTriggerOid);
+	if (fkconstraint->is_enforced)
+		createForeignKeyActionTriggers(RelationGetRelid(rel),
+									   RelationGetRelid(pkrel),
+									   fkconstraint,
+									   parentConstr, indexOid,
+									   parentDelTrigger, parentUpdTrigger,
+									   &deleteTriggerOid, &updateTriggerOid);
 
 	/*
 	 * If the referenced table is partitioned, recurse on ourselves to handle
@@ -10863,8 +10881,8 @@ addFkRecurseReferencing(List **wqueue, Constraint *fkconstraint, Relation rel,
 						Oid parentInsTrigger, Oid parentUpdTrigger,
 						bool with_period)
 {
-	Oid			insertTriggerOid,
-				updateTriggerOid;
+	Oid			insertTriggerOid = InvalidOid,
+				updateTriggerOid = InvalidOid;
 
 	Assert(OidIsValid(parentConstr));
 	Assert(CheckRelationLockedByMe(rel, ShareRowExclusiveLock, true));
@@ -10876,29 +10894,32 @@ addFkRecurseReferencing(List **wqueue, Constraint *fkconstraint, Relation rel,
 				 errmsg("foreign key constraints are not supported on foreign tables")));
 
 	/*
-	 * Add the check triggers to it and, if necessary, schedule it to be
-	 * checked in Phase 3.
+	 * Add check triggers if the constraint is ENFORCED, and if needed,
+	 * schedule them to be checked in Phase 3.
 	 *
 	 * If the relation is partitioned, drill down to do it to its partitions.
 	 */
-	createForeignKeyCheckTriggers(RelationGetRelid(rel),
-								  RelationGetRelid(pkrel),
-								  fkconstraint,
-								  parentConstr,
-								  indexOid,
-								  parentInsTrigger, parentUpdTrigger,
-								  &insertTriggerOid, &updateTriggerOid);
+	if (fkconstraint->is_enforced)
+		createForeignKeyCheckTriggers(RelationGetRelid(rel),
+									  RelationGetRelid(pkrel),
+									  fkconstraint,
+									  parentConstr,
+									  indexOid,
+									  parentInsTrigger, parentUpdTrigger,
+									  &insertTriggerOid, &updateTriggerOid);
 
 	if (rel->rd_rel->relkind == RELKIND_RELATION)
 	{
 		/*
 		 * Tell Phase 3 to check that the constraint is satisfied by existing
-		 * rows. We can skip this during table creation, when requested
-		 * explicitly by specifying NOT VALID in an ADD FOREIGN KEY command,
-		 * and when we're recreating a constraint following a SET DATA TYPE
-		 * operation that did not impugn its validity.
+		 * rows. We can skip this during table creation, when constraint is
+		 * specified as NOT ENFORCED, or when requested explicitly by
+		 * specifying NOT VALID in an ADD FOREIGN KEY command, and when we're
+		 * recreating a constraint following a SET DATA TYPE operation that
+		 * did not impugn its validity.
 		 */
-		if (wqueue && !old_check_ok && !fkconstraint->skip_validation)
+		if (wqueue && !old_check_ok && !fkconstraint->skip_validation &&
+			fkconstraint->is_enforced)
 		{
 			NewConstraint *newcon;
 			AlteredTableInfo *tab;
@@ -11129,8 +11150,8 @@ CloneFkReferenced(Relation parentRel, Relation partitionRel)
 		AttrNumber	confdelsetcols[INDEX_MAX_KEYS];
 		Constraint *fkconstraint;
 		ObjectAddress address;
-		Oid			deleteTriggerOid,
-					updateTriggerOid;
+		Oid			deleteTriggerOid = InvalidOid,
+					updateTriggerOid = InvalidOid;
 
 		tuple = SearchSysCache1(CONSTROID, ObjectIdGetDatum(constrOid));
 		if (!HeapTupleIsValid(tuple))
@@ -11190,8 +11211,9 @@ CloneFkReferenced(Relation parentRel, Relation partitionRel)
 		fkconstraint->fk_del_set_cols = NIL;
 		fkconstraint->old_conpfeqop = NIL;
 		fkconstraint->old_pktable_oid = InvalidOid;
+		fkconstraint->is_enforced = constrForm->conenforced;
 		fkconstraint->skip_validation = false;
-		fkconstraint->initially_valid = true;
+		fkconstraint->initially_valid = constrForm->convalidated;
 
 		/* set up colnames that are used to generate the constraint name */
 		for (int i = 0; i < numfks; i++)
@@ -11219,9 +11241,10 @@ CloneFkReferenced(Relation parentRel, Relation partitionRel)
 		 * parent OIDs for similar triggers that will be created on the
 		 * partition in addFkRecurseReferenced().
 		 */
-		GetForeignKeyActionTriggers(trigrel, constrOid,
-									constrForm->confrelid, constrForm->conrelid,
-									&deleteTriggerOid, &updateTriggerOid);
+		if (constrForm->conenforced)
+			GetForeignKeyActionTriggers(trigrel, constrOid,
+										constrForm->confrelid, constrForm->conrelid,
+										&deleteTriggerOid, &updateTriggerOid);
 
 		/* Add this constraint ... */
 		address = addFkConstraint(addFkReferencedSide,
@@ -11354,8 +11377,8 @@ CloneFkReferencing(List **wqueue, Relation parentRel, Relation partRel)
 		Oid			indexOid;
 		ObjectAddress address;
 		ListCell   *lc;
-		Oid			insertTriggerOid,
-					updateTriggerOid;
+		Oid			insertTriggerOid = InvalidOid,
+					updateTriggerOid = InvalidOid;
 		bool		with_period;
 
 		tuple = SearchSysCache1(CONSTROID, ObjectIdGetDatum(parentConstrOid));
@@ -11387,17 +11410,18 @@ CloneFkReferencing(List **wqueue, Relation parentRel, Relation partRel)
 			mapped_conkey[i] = attmap->attnums[conkey[i] - 1];
 
 		/*
-		 * Get the "check" triggers belonging to the constraint to pass as
-		 * parent OIDs for similar triggers that will be created on the
-		 * partition in addFkRecurseReferencing().  They are also passed to
-		 * tryAttachPartitionForeignKey() below to simply assign as parents to
-		 * the partition's existing "check" triggers, that is, if the
-		 * corresponding constraints is deemed attachable to the parent
-		 * constraint.
+		 * Get the "check" triggers belonging to the constraint, if it is
+		 * ENFORCED, to pass as parent OIDs for similar triggers that will be
+		 * created on the partition in addFkRecurseReferencing().  They are
+		 * also passed to tryAttachPartitionForeignKey() below to simply
+		 * assign as parents to the partition's existing "check" triggers,
+		 * that is, if the corresponding constraints is deemed attachable to
+		 * the parent constraint.
 		 */
-		GetForeignKeyCheckTriggers(trigrel, constrForm->oid,
-								   constrForm->confrelid, constrForm->conrelid,
-								   &insertTriggerOid, &updateTriggerOid);
+		if (constrForm->conenforced)
+			GetForeignKeyCheckTriggers(trigrel, constrForm->oid,
+									   constrForm->confrelid, constrForm->conrelid,
+									   &insertTriggerOid, &updateTriggerOid);
 
 		/*
 		 * Before creating a new constraint, see whether any existing FKs are
@@ -11450,6 +11474,7 @@ CloneFkReferencing(List **wqueue, Relation parentRel, Relation partRel)
 		fkconstraint->fk_del_set_cols = NIL;
 		fkconstraint->old_conpfeqop = NIL;
 		fkconstraint->old_pktable_oid = InvalidOid;
+		fkconstraint->is_enforced = constrForm->conenforced;
 		fkconstraint->skip_validation = false;
 		fkconstraint->initially_valid = constrForm->convalidated;
 		for (int i = 0; i < numfks; i++)
@@ -11564,6 +11589,23 @@ tryAttachPartitionForeignKey(List **wqueue,
 	if (!HeapTupleIsValid(partcontup))
 		elog(ERROR, "cache lookup failed for constraint %u", fk->conoid);
 	partConstr = (Form_pg_constraint) GETSTRUCT(partcontup);
+
+	/*
+	 * An error should be raised if the constraint enforceability is
+	 * different. Returning false without raising an error, as we do for other
+	 * attributes, could lead to a duplicate constraint with the same
+	 * enforceability as the parent. While this may be acceptable, it may not
+	 * be ideal. Therefore, it's better to raise an error and allow the user
+	 * to correct the enforceability before proceeding.
+	 */
+	if (partConstr->conenforced != parentConstr->conenforced)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
+				 errmsg("constraint \"%s\" enforceability conflicts with constraint \"%s\" on relation \"%s\"",
+						NameStr(parentConstr->conname),
+						NameStr(partConstr->conname),
+						RelationGetRelationName(partition))));
+
 	if (OidIsValid(partConstr->conparentid) ||
 		partConstr->condeferrable != parentConstr->condeferrable ||
 		partConstr->condeferred != parentConstr->condeferred ||
@@ -11610,8 +11652,7 @@ AttachPartitionForeignKey(List **wqueue,
 	bool		queueValidation;
 	Oid			partConstrFrelid;
 	Oid			partConstrRelid;
-	Oid			insertTriggerOid,
-				updateTriggerOid;
+	bool		parentConstrIsEnforced;
 
 	/* Fetch the parent constraint tuple */
 	parentConstrTup = SearchSysCache1(CONSTROID,
@@ -11619,6 +11660,7 @@ AttachPartitionForeignKey(List **wqueue,
 	if (!HeapTupleIsValid(parentConstrTup))
 		elog(ERROR, "cache lookup failed for constraint %u", parentConstrOid);
 	parentConstr = (Form_pg_constraint) GETSTRUCT(parentConstrTup);
+	parentConstrIsEnforced = parentConstr->conenforced;
 
 	/* Fetch the child constraint tuple */
 	partcontup = SearchSysCache1(CONSTROID,
@@ -11668,17 +11710,24 @@ AttachPartitionForeignKey(List **wqueue,
 
 	/*
 	 * Like the constraint, attach partition's "check" triggers to the
-	 * corresponding parent triggers.
+	 * corresponding parent triggers if the constraint is ENFORCED. NOT
+	 * ENFORCED constraints do not have these triggers.
 	 */
-	GetForeignKeyCheckTriggers(trigrel,
-							   partConstrOid, partConstrFrelid, partConstrRelid,
-							   &insertTriggerOid, &updateTriggerOid);
-	Assert(OidIsValid(insertTriggerOid) && OidIsValid(parentInsTrigger));
-	TriggerSetParentTrigger(trigrel, insertTriggerOid, parentInsTrigger,
-							RelationGetRelid(partition));
-	Assert(OidIsValid(updateTriggerOid) && OidIsValid(parentUpdTrigger));
-	TriggerSetParentTrigger(trigrel, updateTriggerOid, parentUpdTrigger,
-							RelationGetRelid(partition));
+	if (parentConstrIsEnforced)
+	{
+		Oid			insertTriggerOid,
+					updateTriggerOid;
+
+		GetForeignKeyCheckTriggers(trigrel,
+								   partConstrOid, partConstrFrelid, partConstrRelid,
+								   &insertTriggerOid, &updateTriggerOid);
+		Assert(OidIsValid(insertTriggerOid) && OidIsValid(parentInsTrigger));
+		TriggerSetParentTrigger(trigrel, insertTriggerOid, parentInsTrigger,
+								RelationGetRelid(partition));
+		Assert(OidIsValid(updateTriggerOid) && OidIsValid(parentUpdTrigger));
+		TriggerSetParentTrigger(trigrel, updateTriggerOid, parentUpdTrigger,
+								RelationGetRelid(partition));
+	}
 
 	/*
 	 * We updated this pg_constraint row above to set its parent; validating
@@ -11792,6 +11841,10 @@ RemoveInheritedConstraint(Relation conrel, Relation trigrel, Oid conoid,
  *
  * The subroutine for tryAttachPartitionForeignKey handles the deletion of
  * action triggers for the foreign key constraint.
+ *
+ * If valid confrelid and conrelid values are not provided, the respective
+ * trigger check will be skipped, and the trigger will be considered for
+ * removal.
  */
 static void
 DropForeignKeyConstraintTriggers(Relation trigrel, Oid conoid, Oid confrelid,
@@ -11812,10 +11865,27 @@ DropForeignKeyConstraintTriggers(Relation trigrel, Oid conoid, Oid confrelid,
 		Form_pg_trigger trgform = (Form_pg_trigger) GETSTRUCT(trigtup);
 		ObjectAddress trigger;
 
-		if (trgform->tgconstrrelid != conrelid)
+		/* Invalid if trigger is not for a referential integrity constraint */
+		if (!OidIsValid(trgform->tgconstrrelid))
 			continue;
-		if (trgform->tgrelid != confrelid)
+		if (OidIsValid(conrelid) && trgform->tgconstrrelid != conrelid)
 			continue;
+		if (OidIsValid(confrelid) && trgform->tgrelid != confrelid)
+			continue;
+
+		/* We should be droping trigger related to foreign key constraint */
+		Assert(trgform->tgfoid == F_RI_FKEY_CHECK_INS ||
+			   trgform->tgfoid == F_RI_FKEY_CHECK_UPD ||
+			   trgform->tgfoid == F_RI_FKEY_CASCADE_DEL ||
+			   trgform->tgfoid == F_RI_FKEY_CASCADE_UPD ||
+			   trgform->tgfoid == F_RI_FKEY_RESTRICT_DEL ||
+			   trgform->tgfoid == F_RI_FKEY_RESTRICT_UPD ||
+			   trgform->tgfoid == F_RI_FKEY_SETNULL_DEL ||
+			   trgform->tgfoid == F_RI_FKEY_SETNULL_UPD ||
+			   trgform->tgfoid == F_RI_FKEY_SETDEFAULT_DEL ||
+			   trgform->tgfoid == F_RI_FKEY_SETDEFAULT_UPD ||
+			   trgform->tgfoid == F_RI_FKEY_NOACTION_DEL ||
+			   trgform->tgfoid == F_RI_FKEY_NOACTION_UPD);
 
 		/*
 		 * The constraint is originally set up to contain this trigger as an
@@ -12028,6 +12098,11 @@ ATExecAlterConstraint(List **wqueue, Relation rel, ATAlterConstraint *cmdcon,
 				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 				 errmsg("constraint \"%s\" of relation \"%s\" is not a foreign key constraint",
 						cmdcon->conname, RelationGetRelationName(rel))));
+	if (cmdcon->alterEnforceability && currcon->contype != CONSTRAINT_FOREIGN)
+		ereport(ERROR,
+				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				 errmsg("cannot alter enforceability of constraint \"%s\" of relation \"%s\"",
+						cmdcon->conname, RelationGetRelationName(rel))));
 	if (cmdcon->alterInheritability &&
 		currcon->contype != CONSTRAINT_NOTNULL)
 		ereport(ERROR,
@@ -12107,7 +12182,7 @@ ATExecAlterConstraint(List **wqueue, Relation rel, ATAlterConstraint *cmdcon,
 
 /*
  * A subroutine of ATExecAlterConstraint that calls the respective routines for
- * altering constraint attributes.
+ * altering constraint's enforceability, deferrability or inheritability.
  */
 static bool
 ATExecAlterConstraintInternal(List **wqueue, ATAlterConstraint *cmdcon,
@@ -12115,16 +12190,35 @@ ATExecAlterConstraintInternal(List **wqueue, ATAlterConstraint *cmdcon,
 							  HeapTuple contuple, bool recurse,
 							  LOCKMODE lockmode)
 {
+	Form_pg_constraint currcon;
 	bool		changed = false;
 	List	   *otherrelids = NIL;
 
+	currcon = (Form_pg_constraint) GETSTRUCT(contuple);
+
 	/*
-	 * Do the catalog work for the deferrability change, recurse if necessary.
-	 */
-	if (cmdcon->alterDeferrability &&
-		ATExecAlterConstrDeferrability(wqueue, cmdcon, conrel, tgrel, rel,
-									   contuple, recurse, &otherrelids,
-									   lockmode))
+	 * Do the catalog work for the enforceability or deferrability change,
+	 * recurse if necessary.
+	 *
+	 * Note that even if deferrability is requested to be altered along with
+	 * enforceability, we don't need to explicitly update multiple entries in
+	 * pg_trigger related to deferrability.
+	 *
+	 * Modifying enforceability involves either creating or dropping the
+	 * trigger, during which the deferrability setting will be adjusted
+	 * automatically.
+	 */
+	if (cmdcon->alterEnforceability &&
+		ATExecAlterConstrEnforceability(wqueue, cmdcon, conrel, tgrel,
+										currcon->conrelid, currcon->confrelid,
+										contuple, lockmode, InvalidOid,
+										InvalidOid, InvalidOid, InvalidOid))
+		changed = true;
+
+	else if (cmdcon->alterDeferrability &&
+			 ATExecAlterConstrDeferrability(wqueue, cmdcon, conrel, tgrel, rel,
+											contuple, recurse, &otherrelids,
+											lockmode))
 	{
 		/*
 		 * AlterConstrUpdateConstraintEntry already invalidated relcache for
@@ -12149,6 +12243,151 @@ ATExecAlterConstraintInternal(List **wqueue, ATAlterConstraint *cmdcon,
 	return changed;
 }
 
+/*
+ * Returns true if the constraint's enforceability is altered.
+ *
+ * Depending on whether the constraint is being set to ENFORCED or NOT
+ * ENFORCED, it creates or drops the trigger accordingly.
+ *
+ * Note that we must recurse even when trying to change a constraint to not
+ * enforced if it is already not enforced, in case descendant constraints
+ * might be enforced and need to be changed to not enforced. Conversely, we
+ * should do nothing if a constraint is being set to enforced and is already
+ * enforced, as descendant constraints cannot be different in that case.
+ */
+static bool
+ATExecAlterConstrEnforceability(List **wqueue, ATAlterConstraint *cmdcon,
+								Relation conrel, Relation tgrel,
+								const Oid fkrelid, const Oid pkrelid,
+								HeapTuple contuple, LOCKMODE lockmode,
+								Oid ReferencedParentDelTrigger,
+								Oid ReferencedParentUpdTrigger,
+								Oid ReferencingParentInsTrigger,
+								Oid ReferencingParentUpdTrigger)
+{
+	Form_pg_constraint currcon;
+	Oid			conoid;
+	Relation	rel;
+	bool		changed = false;
+
+	/* Since this function recurses, it could be driven to stack overflow */
+	check_stack_depth();
+
+	Assert(cmdcon->alterEnforceability);
+
+	currcon = (Form_pg_constraint) GETSTRUCT(contuple);
+	conoid = currcon->oid;
+
+	/* Should be foreign key constraint */
+	Assert(currcon->contype == CONSTRAINT_FOREIGN);
+
+	rel = table_open(currcon->conrelid, lockmode);
+
+	if (currcon->conenforced != cmdcon->is_enforced)
+	{
+		AlterConstrUpdateConstraintEntry(cmdcon, conrel, contuple);
+		changed = true;
+	}
+
+	/* Drop triggers */
+	if (!cmdcon->is_enforced)
+	{
+		/*
+		 * When setting a constraint to NOT ENFORCED, the constraint triggers
+		 * need to be dropped. Therefore, we must process the child relations
+		 * first, followed by the parent, to account for dependencies.
+		 */
+		if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE ||
+			get_rel_relkind(currcon->confrelid) == RELKIND_PARTITIONED_TABLE)
+			AlterConstrEnforceabilityRecurse(wqueue, cmdcon, conrel, tgrel,
+											 fkrelid, pkrelid, contuple,
+											 lockmode, InvalidOid, InvalidOid,
+											 InvalidOid, InvalidOid);
+
+		/* Drop all the triggers */
+		DropForeignKeyConstraintTriggers(tgrel, conoid, InvalidOid, InvalidOid);
+	}
+	else if (changed)			/* Create triggers */
+	{
+		Oid			ReferencedDelTriggerOid = InvalidOid,
+					ReferencedUpdTriggerOid = InvalidOid,
+					ReferencingInsTriggerOid = InvalidOid,
+					ReferencingUpdTriggerOid = InvalidOid;
+
+		/* Prepare the minimal information required for trigger creation. */
+		Constraint *fkconstraint = makeNode(Constraint);
+
+		fkconstraint->conname = pstrdup(NameStr(currcon->conname));
+		fkconstraint->fk_matchtype = currcon->confmatchtype;
+		fkconstraint->fk_upd_action = currcon->confupdtype;
+		fkconstraint->fk_del_action = currcon->confdeltype;
+
+		/* Create referenced triggers */
+		if (currcon->conrelid == fkrelid)
+			createForeignKeyActionTriggers(currcon->conrelid,
+										   currcon->confrelid,
+										   fkconstraint,
+										   conoid,
+										   currcon->conindid,
+										   ReferencedParentDelTrigger,
+										   ReferencedParentUpdTrigger,
+										   &ReferencedDelTriggerOid,
+										   &ReferencedUpdTriggerOid);
+
+		/* Create referencing triggers */
+		if (currcon->confrelid == pkrelid)
+			createForeignKeyCheckTriggers(currcon->conrelid,
+										  pkrelid,
+										  fkconstraint,
+										  conoid,
+										  currcon->conindid,
+										  ReferencingParentInsTrigger,
+										  ReferencingParentUpdTrigger,
+										  &ReferencingInsTriggerOid,
+										  &ReferencingUpdTriggerOid);
+
+		/*
+		 * Tell Phase 3 to check that the constraint is satisfied by existing
+		 * rows.
+		 */
+		if (rel->rd_rel->relkind == RELKIND_RELATION)
+		{
+			AlteredTableInfo *tab;
+			NewConstraint *newcon;
+
+			newcon = (NewConstraint *) palloc0(sizeof(NewConstraint));
+			newcon->name = fkconstraint->conname;
+			newcon->contype = CONSTR_FOREIGN;
+			newcon->refrelid = currcon->confrelid;
+			newcon->refindid = currcon->conindid;
+			newcon->conid = currcon->oid;
+			newcon->qual = (Node *) fkconstraint;
+
+			/* Find or create work queue entry for this table */
+			tab = ATGetQueueEntry(wqueue, rel);
+			tab->constraints = lappend(tab->constraints, newcon);
+		}
+
+		/*
+		 * If the table at either end of the constraint is partitioned, we
+		 * need to recurse and create triggers for each constraint that is a
+		 * child of this one.
+		 */
+		if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE ||
+			get_rel_relkind(currcon->confrelid) == RELKIND_PARTITIONED_TABLE)
+			AlterConstrEnforceabilityRecurse(wqueue, cmdcon, conrel, tgrel,
+											 fkrelid, pkrelid, contuple,
+											 lockmode, ReferencedDelTriggerOid,
+											 ReferencedUpdTriggerOid,
+											 ReferencingInsTriggerOid,
+											 ReferencingUpdTriggerOid);
+	}
+
+	table_close(rel, NoLock);
+
+	return changed;
+}
+
 /*
  * Returns true if the constraint's deferrability is altered.
  *
@@ -12353,6 +12592,55 @@ AlterConstrTriggerDeferrability(Oid conoid, Relation tgrel, Relation rel,
 	systable_endscan(tgscan);
 }
 
+/*
+ * Invokes ATExecAlterConstrEnforceability for each constraint that is a child of
+ * the specified constraint.
+ *
+ * Note that this doesn't handle recursion the normal way, viz. by scanning the
+ * list of child relations and recursing; instead it uses the conparentid
+ * relationships.  This may need to be reconsidered.
+ *
+ * The arguments to this function have the same meaning as the arguments to
+ * ATExecAlterConstrEnforceability.
+ */
+static void
+AlterConstrEnforceabilityRecurse(List **wqueue, ATAlterConstraint *cmdcon,
+								 Relation conrel, Relation tgrel,
+								 const Oid fkrelid, const Oid pkrelid,
+								 HeapTuple contuple, LOCKMODE lockmode,
+								 Oid ReferencedParentDelTrigger,
+								 Oid ReferencedParentUpdTrigger,
+								 Oid ReferencingParentInsTrigger,
+								 Oid ReferencingParentUpdTrigger)
+{
+	Form_pg_constraint currcon;
+	Oid			conoid;
+	ScanKeyData pkey;
+	SysScanDesc pscan;
+	HeapTuple	childtup;
+
+	currcon = (Form_pg_constraint) GETSTRUCT(contuple);
+	conoid = currcon->oid;
+
+	ScanKeyInit(&pkey,
+				Anum_pg_constraint_conparentid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(conoid));
+
+	pscan = systable_beginscan(conrel, ConstraintParentIndexId,
+							   true, NULL, 1, &pkey);
+
+	while (HeapTupleIsValid(childtup = systable_getnext(pscan)))
+		ATExecAlterConstrEnforceability(wqueue, cmdcon, conrel, tgrel, fkrelid,
+										pkrelid, childtup, lockmode,
+										ReferencedParentDelTrigger,
+										ReferencedParentUpdTrigger,
+										ReferencingParentInsTrigger,
+										ReferencingParentUpdTrigger);
+
+	systable_endscan(pscan);
+}
+
 /*
  * Invokes ATExecAlterConstrDeferrability for each constraint that is a child of
  * the specified constraint.
@@ -12413,11 +12701,25 @@ AlterConstrUpdateConstraintEntry(ATAlterConstraint *cmdcon, Relation conrel,
 	HeapTuple	copyTuple;
 	Form_pg_constraint copy_con;
 
-	Assert(cmdcon->alterDeferrability || cmdcon->alterInheritability);
+	Assert(cmdcon->alterEnforceability || cmdcon->alterDeferrability ||
+		   cmdcon->alterInheritability);
 
 	copyTuple = heap_copytuple(contuple);
 	copy_con = (Form_pg_constraint) GETSTRUCT(copyTuple);
 
+	if (cmdcon->alterEnforceability)
+	{
+		copy_con->conenforced = cmdcon->is_enforced;
+
+		/*
+		 * NB: The convalidated status is irrelevant when the constraint is
+		 * set to NOT ENFORCED, but for consistency, it should still be set
+		 * appropriately. Similarly, if the constraint is later changed to
+		 * ENFORCED, validation will be performed during phase 3, so it makes
+		 * sense to mark it as valid in that case.
+		 */
+		copy_con->convalidated = cmdcon->is_enforced;
+	}
 	if (cmdcon->alterDeferrability)
 	{
 		copy_con->condeferrable = cmdcon->deferrable;
@@ -17137,9 +17439,9 @@ MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel)
 								NameStr(child_con->conname), RelationGetRelationName(child_rel))));
 
 			/*
-			 * A non-enforced child constraint cannot be merged with an
-			 * enforced parent constraint. However, the reverse is allowed,
-			 * where the child constraint is enforced.
+			 * A NOT ENFORCED child constraint cannot be merged with an
+			 * ENFORCED parent constraint. However, the reverse is allowed,
+			 * where the child constraint is ENFORCED.
 			 */
 			if (parent_con->conenforced && !child_con->conenforced)
 				ereport(ERROR,
@@ -20510,8 +20812,6 @@ DetachPartitionFinalize(Relation rel, Relation partRel, bool concurrent,
 		ForeignKeyCacheInfo *fk = lfirst(cell);
 		HeapTuple	contup;
 		Form_pg_constraint conform;
-		Oid			insertTriggerOid,
-					updateTriggerOid;
 
 		contup = SearchSysCache1(CONSTROID, ObjectIdGetDatum(fk->conoid));
 		if (!HeapTupleIsValid(contup))
@@ -20538,17 +20838,25 @@ DetachPartitionFinalize(Relation rel, Relation partRel, bool concurrent,
 
 		/*
 		 * Also, look up the partition's "check" triggers corresponding to the
-		 * constraint being detached and detach them from the parent triggers.
+		 * ENFORCED constraint being detached and detach them from the parent
+		 * triggers. NOT ENFORCED constraints do not have these triggers;
+		 * therefore, this step is not needed.
 		 */
-		GetForeignKeyCheckTriggers(trigrel,
-								   fk->conoid, fk->confrelid, fk->conrelid,
-								   &insertTriggerOid, &updateTriggerOid);
-		Assert(OidIsValid(insertTriggerOid));
-		TriggerSetParentTrigger(trigrel, insertTriggerOid, InvalidOid,
-								RelationGetRelid(partRel));
-		Assert(OidIsValid(updateTriggerOid));
-		TriggerSetParentTrigger(trigrel, updateTriggerOid, InvalidOid,
-								RelationGetRelid(partRel));
+		if (fk->conenforced)
+		{
+			Oid			insertTriggerOid,
+						updateTriggerOid;
+
+			GetForeignKeyCheckTriggers(trigrel,
+									   fk->conoid, fk->confrelid, fk->conrelid,
+									   &insertTriggerOid, &updateTriggerOid);
+			Assert(OidIsValid(insertTriggerOid));
+			TriggerSetParentTrigger(trigrel, insertTriggerOid, InvalidOid,
+									RelationGetRelid(partRel));
+			Assert(OidIsValid(updateTriggerOid));
+			TriggerSetParentTrigger(trigrel, updateTriggerOid, InvalidOid,
+									RelationGetRelid(partRel));
+		}
 
 		/*
 		 * Lastly, create the action triggers on the referenced table, using
@@ -20588,8 +20896,9 @@ DetachPartitionFinalize(Relation rel, Relation partRel, bool concurrent,
 			fkconstraint->conname = pstrdup(NameStr(conform->conname));
 			fkconstraint->deferrable = conform->condeferrable;
 			fkconstraint->initdeferred = conform->condeferred;
+			fkconstraint->is_enforced = conform->conenforced;
 			fkconstraint->skip_validation = true;
-			fkconstraint->initially_valid = true;
+			fkconstraint->initially_valid = conform->convalidated;
 			/* a few irrelevant fields omitted here */
 			fkconstraint->pktable = NULL;
 			fkconstraint->fk_attrs = NIL;

src/backend/optimizer/util/plancat.c

@@ -640,6 +640,10 @@ get_relation_foreign_keys(PlannerInfo *root, RelOptInfo *rel,
 		/* conrelid should always be that of the table we're considering */
 		Assert(cachedfk->conrelid == RelationGetRelid(relation));
 
+		/* skip constraints currently not enforced */
+		if (!cachedfk->conenforced)
+			continue;
+
 		/* Scan to find other RTEs matching confrelid */
 		rti = 0;
 		foreach(lc2, rtable)

src/backend/parser/gram.y

@@ -2662,6 +2662,8 @@ alter_table_cmd:
 					n->subtype = AT_AlterConstraint;
 					n->def = (Node *) c;
 					c->conname = $3;
+					if ($4 & (CAS_NOT_ENFORCED | CAS_ENFORCED))
+						c->alterEnforceability = true;
 					if ($4 & (CAS_DEFERRABLE | CAS_NOT_DEFERRABLE |
 							  CAS_INITIALLY_DEFERRED | CAS_INITIALLY_IMMEDIATE))
 						c->alterDeferrability = true;
@@ -2670,7 +2672,10 @@ alter_table_cmd:
 					processCASbits($4, @4, "FOREIGN KEY",
 									&c->deferrable,
 									&c->initdeferred,
-									NULL, NULL, &c->noinherit, yyscanner);
+									&c->is_enforced,
+									NULL,
+									&c->noinherit,
+									yyscanner);
 					$$ = (Node *) n;
 				}
 			/* ALTER TABLE <name> ALTER CONSTRAINT INHERIT */
@@ -4334,7 +4339,7 @@ ConstraintElem:
 					n->fk_del_set_cols = ($11)->deleteAction->cols;
 					processCASbits($12, @12, "FOREIGN KEY",
 								   &n->deferrable, &n->initdeferred,
-								   NULL, &n->skip_validation, NULL,
+								   &n->is_enforced, &n->skip_validation, NULL,
 								   yyscanner);
 					n->initially_valid = !n->skip_validation;
 					$$ = (Node *) n;

src/backend/parser/parse_utilcmd.c

@@ -2962,8 +2962,10 @@ transformFKConstraints(CreateStmtContext *cxt,
 
 	/*
 	 * If CREATE TABLE or adding a column with NULL default, we can safely
-	 * skip validation of FK constraints, and nonetheless mark them valid.
-	 * (This will override any user-supplied NOT VALID flag.)
+	 * skip validation of FK constraints, and mark them as valid based on the
+	 * constraint enforcement flag, since NOT ENFORCED constraints must always
+	 * be marked as NOT VALID. (This will override any user-supplied NOT VALID
+	 * flag.)
 	 */
 	if (skipValidation)
 	{
@@ -2972,7 +2974,7 @@ transformFKConstraints(CreateStmtContext *cxt,
 			Constraint *constraint = (Constraint *) lfirst(fkclist);
 
 			constraint->skip_validation = true;
-			constraint->initially_valid = true;
+			constraint->initially_valid = constraint->is_enforced;
 		}
 	}
 
@@ -3967,7 +3969,8 @@ transformConstraintAttrs(CreateStmtContext *cxt, List *constraintList)
 
 			case CONSTR_ATTR_ENFORCED:
 				if (lastprimarycon == NULL ||
-					lastprimarycon->contype != CONSTR_CHECK)
+					(lastprimarycon->contype != CONSTR_CHECK &&
+					 lastprimarycon->contype != CONSTR_FOREIGN))
 					ereport(ERROR,
 							(errcode(ERRCODE_SYNTAX_ERROR),
 							 errmsg("misplaced ENFORCED clause"),
@@ -3983,7 +3986,8 @@ transformConstraintAttrs(CreateStmtContext *cxt, List *constraintList)
 
 			case CONSTR_ATTR_NOT_ENFORCED:
 				if (lastprimarycon == NULL ||
-					lastprimarycon->contype != CONSTR_CHECK)
+					(lastprimarycon->contype != CONSTR_CHECK &&
+					 lastprimarycon->contype != CONSTR_FOREIGN))
 					ereport(ERROR,
 							(errcode(ERRCODE_SYNTAX_ERROR),
 							 errmsg("misplaced NOT ENFORCED clause"),

src/backend/utils/cache/relcache.c

@@ -4666,11 +4666,6 @@ RelationGetFKeyList(Relation relation)
 	if (relation->rd_fkeyvalid)
 		return relation->rd_fkeylist;
 
-	/* Fast path: non-partitioned tables without triggers can't have FKs */
-	if (!relation->rd_rel->relhastriggers &&
-		relation->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
-		return NIL;
-
 	/*
 	 * We build the list we intend to return (in the caller's context) while
 	 * doing the scan.  After successfully completing the scan, we copy that
@@ -4702,6 +4697,7 @@ RelationGetFKeyList(Relation relation)
 		info->conoid = constraint->oid;
 		info->conrelid = constraint->conrelid;
 		info->confrelid = constraint->confrelid;
+		info->conenforced = constraint->conenforced;
 
 		DeconstructFkConstraintRow(htup, &info->nkeys,
 								   info->conkey,

src/bin/pg_dump/pg_dump.c

@@ -8084,13 +8084,7 @@ getConstraints(Archive *fout, TableInfo tblinfo[], int numTables)
 	{
 		TableInfo  *tinfo = &tblinfo[i];
 
-		/*
-		 * For partitioned tables, foreign keys have no triggers so they must
-		 * be included anyway in case some foreign keys are defined.
-		 */
-		if ((!tinfo->hastriggers &&
-			 tinfo->relkind != RELKIND_PARTITIONED_TABLE) ||
-			!(tinfo->dobj.dump & DUMP_COMPONENT_DEFINITION))
+		if (!(tinfo->dobj.dump & DUMP_COMPONENT_DEFINITION))
 			continue;
 
 		/* OK, we need info for this table */

src/bin/psql/describe.c

@@ -2550,136 +2550,124 @@ describeOneTableDetails(const char *schemaname,
 			PQclear(result);
 		}
 
-		/*
-		 * Print foreign-key constraints (there are none if no triggers,
-		 * except if the table is partitioned, in which case the triggers
-		 * appear in the partitions)
-		 */
-		if (tableinfo.hastriggers ||
-			tableinfo.relkind == RELKIND_PARTITIONED_TABLE)
+		/* Print foreign-key constraints */
+		if (pset.sversion >= 120000 &&
+			(tableinfo.ispartition || tableinfo.relkind == RELKIND_PARTITIONED_TABLE))
 		{
-			if (pset.sversion >= 120000 &&
-				(tableinfo.ispartition || tableinfo.relkind == RELKIND_PARTITIONED_TABLE))
-			{
-				/*
-				 * Put the constraints defined in this table first, followed
-				 * by the constraints defined in ancestor partitioned tables.
-				 */
-				printfPQExpBuffer(&buf,
-								  "SELECT conrelid = '%s'::pg_catalog.regclass AS sametable,\n"
-								  "       conname,\n"
-								  "       pg_catalog.pg_get_constraintdef(oid, true) AS condef,\n"
-								  "       conrelid::pg_catalog.regclass AS ontable\n"
-								  "  FROM pg_catalog.pg_constraint,\n"
-								  "       pg_catalog.pg_partition_ancestors('%s')\n"
-								  " WHERE conrelid = relid AND contype = " CppAsString2(CONSTRAINT_FOREIGN) " AND conparentid = 0\n"
-								  "ORDER BY sametable DESC, conname;",
-								  oid, oid);
-			}
-			else
-			{
-				printfPQExpBuffer(&buf,
-								  "SELECT true as sametable, conname,\n"
-								  "  pg_catalog.pg_get_constraintdef(r.oid, true) as condef,\n"
-								  "  conrelid::pg_catalog.regclass AS ontable\n"
-								  "FROM pg_catalog.pg_constraint r\n"
-								  "WHERE r.conrelid = '%s' AND r.contype = " CppAsString2(CONSTRAINT_FOREIGN) "\n",
-								  oid);
-
-				if (pset.sversion >= 120000)
-					appendPQExpBufferStr(&buf, "     AND conparentid = 0\n");
-				appendPQExpBufferStr(&buf, "ORDER BY conname");
-			}
+			/*
+			 * Put the constraints defined in this table first, followed by
+			 * the constraints defined in ancestor partitioned tables.
+			 */
+			printfPQExpBuffer(&buf,
+							  "SELECT conrelid = '%s'::pg_catalog.regclass AS sametable,\n"
+							  "       conname,\n"
+							  "       pg_catalog.pg_get_constraintdef(oid, true) AS condef,\n"
+							  "       conrelid::pg_catalog.regclass AS ontable\n"
+							  "  FROM pg_catalog.pg_constraint,\n"
+							  "       pg_catalog.pg_partition_ancestors('%s')\n"
+							  " WHERE conrelid = relid AND contype = " CppAsString2(CONSTRAINT_FOREIGN) " AND conparentid = 0\n"
+							  "ORDER BY sametable DESC, conname;",
+							  oid, oid);
+		}
+		else
+		{
+			printfPQExpBuffer(&buf,
+							  "SELECT true as sametable, conname,\n"
+							  "  pg_catalog.pg_get_constraintdef(r.oid, true) as condef,\n"
+							  "  conrelid::pg_catalog.regclass AS ontable\n"
+							  "FROM pg_catalog.pg_constraint r\n"
+							  "WHERE r.conrelid = '%s' AND r.contype = " CppAsString2(CONSTRAINT_FOREIGN) "\n",
+							  oid);
 
-			result = PSQLexec(buf.data);
-			if (!result)
-				goto error_return;
-			else
-				tuples = PQntuples(result);
+			if (pset.sversion >= 120000)
+				appendPQExpBufferStr(&buf, "     AND conparentid = 0\n");
+			appendPQExpBufferStr(&buf, "ORDER BY conname");
+		}
 
-			if (tuples > 0)
-			{
-				int			i_sametable = PQfnumber(result, "sametable"),
-							i_conname = PQfnumber(result, "conname"),
-							i_condef = PQfnumber(result, "condef"),
-							i_ontable = PQfnumber(result, "ontable");
+		result = PSQLexec(buf.data);
+		if (!result)
+			goto error_return;
+		else
+			tuples = PQntuples(result);
 
-				printTableAddFooter(&cont, _("Foreign-key constraints:"));
-				for (i = 0; i < tuples; i++)
-				{
-					/*
-					 * Print untranslated constraint name and definition. Use
-					 * a "TABLE tab" prefix when the constraint is defined in
-					 * a parent partitioned table.
-					 */
-					if (strcmp(PQgetvalue(result, i, i_sametable), "f") == 0)
-						printfPQExpBuffer(&buf, "    TABLE \"%s\" CONSTRAINT \"%s\" %s",
-										  PQgetvalue(result, i, i_ontable),
-										  PQgetvalue(result, i, i_conname),
-										  PQgetvalue(result, i, i_condef));
-					else
-						printfPQExpBuffer(&buf, "    \"%s\" %s",
-										  PQgetvalue(result, i, i_conname),
-										  PQgetvalue(result, i, i_condef));
+		if (tuples > 0)
+		{
+			int			i_sametable = PQfnumber(result, "sametable"),
+						i_conname = PQfnumber(result, "conname"),
+						i_condef = PQfnumber(result, "condef"),
+						i_ontable = PQfnumber(result, "ontable");
 
-					printTableAddFooter(&cont, buf.data);
-				}
+			printTableAddFooter(&cont, _("Foreign-key constraints:"));
+			for (i = 0; i < tuples; i++)
+			{
+				/*
+				 * Print untranslated constraint name and definition. Use a
+				 * "TABLE tab" prefix when the constraint is defined in a
+				 * parent partitioned table.
+				 */
+				if (strcmp(PQgetvalue(result, i, i_sametable), "f") == 0)
+					printfPQExpBuffer(&buf, "    TABLE \"%s\" CONSTRAINT \"%s\" %s",
+									  PQgetvalue(result, i, i_ontable),
+									  PQgetvalue(result, i, i_conname),
+									  PQgetvalue(result, i, i_condef));
+				else
+					printfPQExpBuffer(&buf, "    \"%s\" %s",
+									  PQgetvalue(result, i, i_conname),
+									  PQgetvalue(result, i, i_condef));
+
+				printTableAddFooter(&cont, buf.data);
 			}
-			PQclear(result);
 		}
+		PQclear(result);
 
 		/* print incoming foreign-key references */
-		if (tableinfo.hastriggers ||
-			tableinfo.relkind == RELKIND_PARTITIONED_TABLE)
+		if (pset.sversion >= 120000)
 		{
-			if (pset.sversion >= 120000)
-			{
-				printfPQExpBuffer(&buf,
-								  "SELECT conname, conrelid::pg_catalog.regclass AS ontable,\n"
-								  "       pg_catalog.pg_get_constraintdef(oid, true) AS condef\n"
-								  "  FROM pg_catalog.pg_constraint c\n"
-								  " WHERE confrelid IN (SELECT pg_catalog.pg_partition_ancestors('%s')\n"
-								  "                     UNION ALL VALUES ('%s'::pg_catalog.regclass))\n"
-								  "       AND contype = " CppAsString2(CONSTRAINT_FOREIGN) " AND conparentid = 0\n"
-								  "ORDER BY conname;",
-								  oid, oid);
-			}
-			else
-			{
-				printfPQExpBuffer(&buf,
-								  "SELECT conname, conrelid::pg_catalog.regclass AS ontable,\n"
-								  "       pg_catalog.pg_get_constraintdef(oid, true) AS condef\n"
-								  "  FROM pg_catalog.pg_constraint\n"
-								  " WHERE confrelid = %s AND contype = " CppAsString2(CONSTRAINT_FOREIGN) "\n"
-								  "ORDER BY conname;",
-								  oid);
-			}
+			printfPQExpBuffer(&buf,
+							  "SELECT conname, conrelid::pg_catalog.regclass AS ontable,\n"
+							  "       pg_catalog.pg_get_constraintdef(oid, true) AS condef\n"
+							  "  FROM pg_catalog.pg_constraint c\n"
+							  " WHERE confrelid IN (SELECT pg_catalog.pg_partition_ancestors('%s')\n"
+							  "                     UNION ALL VALUES ('%s'::pg_catalog.regclass))\n"
+							  "       AND contype = " CppAsString2(CONSTRAINT_FOREIGN) " AND conparentid = 0\n"
+							  "ORDER BY conname;",
+							  oid, oid);
+		}
+		else
+		{
+			printfPQExpBuffer(&buf,
+							  "SELECT conname, conrelid::pg_catalog.regclass AS ontable,\n"
+							  "       pg_catalog.pg_get_constraintdef(oid, true) AS condef\n"
+							  "  FROM pg_catalog.pg_constraint\n"
+							  " WHERE confrelid = %s AND contype = " CppAsString2(CONSTRAINT_FOREIGN) "\n"
+							  "ORDER BY conname;",
+							  oid);
+		}
 
-			result = PSQLexec(buf.data);
-			if (!result)
-				goto error_return;
-			else
-				tuples = PQntuples(result);
+		result = PSQLexec(buf.data);
+		if (!result)
+			goto error_return;
+		else
+			tuples = PQntuples(result);
 
-			if (tuples > 0)
-			{
-				int			i_conname = PQfnumber(result, "conname"),
-							i_ontable = PQfnumber(result, "ontable"),
-							i_condef = PQfnumber(result, "condef");
+		if (tuples > 0)
+		{
+			int			i_conname = PQfnumber(result, "conname"),
+						i_ontable = PQfnumber(result, "ontable"),
+						i_condef = PQfnumber(result, "condef");
 
-				printTableAddFooter(&cont, _("Referenced by:"));
-				for (i = 0; i < tuples; i++)
-				{
-					printfPQExpBuffer(&buf, "    TABLE \"%s\" CONSTRAINT \"%s\" %s",
-									  PQgetvalue(result, i, i_ontable),
-									  PQgetvalue(result, i, i_conname),
-									  PQgetvalue(result, i, i_condef));
+			printTableAddFooter(&cont, _("Referenced by:"));
+			for (i = 0; i < tuples; i++)
+			{
+				printfPQExpBuffer(&buf, "    TABLE \"%s\" CONSTRAINT \"%s\" %s",
+								  PQgetvalue(result, i, i_ontable),
+								  PQgetvalue(result, i, i_conname),
+								  PQgetvalue(result, i, i_condef));
 
-					printTableAddFooter(&cont, buf.data);
-				}
+				printTableAddFooter(&cont, buf.data);
 			}
-			PQclear(result);
 		}
+		PQclear(result);
 
 		/* print any row-level policies */
 		if (pset.sversion >= 90500)

src/include/nodes/parsenodes.h

@@ -2495,6 +2495,8 @@ typedef struct ATAlterConstraint
 {
 	NodeTag		type;
 	char	   *conname;		/* Constraint name */
+	bool		alterEnforceability;	/* changing enforceability properties? */
+	bool		is_enforced;	/* ENFORCED? */
 	bool		alterDeferrability; /* changing deferrability properties? */
 	bool		deferrable;		/* DEFERRABLE? */
 	bool		initdeferred;	/* INITIALLY DEFERRED? */

src/include/utils/rel.h

@@ -284,6 +284,9 @@ typedef struct ForeignKeyCacheInfo
 	/* number of columns in the foreign key */
 	int			nkeys;
 
+	/* Is enforced ? */
+	bool		conenforced;
+
 	/*
 	 * these arrays each have nkeys valid entries:
 	 */

src/test/regress/expected/constraints.out

@@ -745,13 +745,9 @@ ERROR:  misplaced NOT ENFORCED clause
 LINE 1: CREATE TABLE UNIQUE_NOTEN_TBL(i int UNIQUE NOT ENFORCED);
                                                    ^
 ALTER TABLE unique_tbl ALTER CONSTRAINT unique_tbl_i_key ENFORCED;
-ERROR:  FOREIGN KEY constraints cannot be marked ENFORCED
-LINE 1: ...TABLE unique_tbl ALTER CONSTRAINT unique_tbl_i_key ENFORCED;
-                                                              ^
+ERROR:  cannot alter enforceability of constraint "unique_tbl_i_key" of relation "unique_tbl"
 ALTER TABLE unique_tbl ALTER CONSTRAINT unique_tbl_i_key NOT ENFORCED;
-ERROR:  FOREIGN KEY constraints cannot be marked NOT ENFORCED
-LINE 1: ...ABLE unique_tbl ALTER CONSTRAINT unique_tbl_i_key NOT ENFORC...
-                                                             ^
+ERROR:  cannot alter enforceability of constraint "unique_tbl_i_key" of relation "unique_tbl"
 DROP TABLE unique_tbl;
 --
 -- EXCLUDE constraints

src/test/regress/expected/foreign_key.out

@@ -1,21 +1,49 @@
 --
 -- FOREIGN KEY
 --
--- MATCH FULL
+-- NOT ENFORCED
 --
 -- First test, check and cascade
 --
 CREATE TABLE PKTABLE ( ptest1 int PRIMARY KEY, ptest2 text );
-CREATE TABLE FKTABLE ( ftest1 int REFERENCES PKTABLE MATCH FULL ON DELETE CASCADE ON UPDATE CASCADE, ftest2 int );
--- Insert test data into PKTABLE
+CREATE TABLE FKTABLE ( ftest1 int CONSTRAINT fktable_ftest1_fkey REFERENCES PKTABLE MATCH FULL ON DELETE CASCADE ON UPDATE CASCADE NOT ENFORCED,
+					   ftest2 int );
+-- Inserting into the foreign key table will not result in an error, even if
+-- there is no matching key in the referenced table.
+INSERT INTO FKTABLE VALUES (1, 2);
+INSERT INTO FKTABLE VALUES (2, 3);
+-- Check FKTABLE
+SELECT * FROM FKTABLE;
+ ftest1 | ftest2 
+--------+--------
+      1 |      2
+      2 |      3
+(2 rows)
+
+-- Reverting it back to ENFORCED will result in failure because constraint validation will be triggered,
+-- as it was previously in a valid state.
+ALTER TABLE FKTABLE ALTER CONSTRAINT fktable_ftest1_fkey ENFORCED;
+ERROR:  insert or update on table "fktable" violates foreign key constraint "fktable_ftest1_fkey"
+DETAIL:  Key (ftest1)=(1) is not present in table "pktable".
+-- Insert referenced data that satisfies the constraint, then attempt to
+-- change it.
 INSERT INTO PKTABLE VALUES (1, 'Test1');
 INSERT INTO PKTABLE VALUES (2, 'Test2');
+ALTER TABLE FKTABLE ALTER CONSTRAINT fktable_ftest1_fkey ENFORCED;
+-- Any further inserts will fail due to the enforcement.
+INSERT INTO FKTABLE VALUES (3, 4);
+ERROR:  insert or update on table "fktable" violates foreign key constraint "fktable_ftest1_fkey"
+DETAIL:  Key (ftest1)=(3) is not present in table "pktable".
+--
+-- MATCH FULL
+--
+-- First test, check and cascade
+--
+-- Insert test data into PKTABLE
 INSERT INTO PKTABLE VALUES (3, 'Test3');
 INSERT INTO PKTABLE VALUES (4, 'Test4');
 INSERT INTO PKTABLE VALUES (5, 'Test5');
 -- Insert successful rows into FK TABLE
-INSERT INTO FKTABLE VALUES (1, 2);
-INSERT INTO FKTABLE VALUES (2, 3);
 INSERT INTO FKTABLE VALUES (3, 4);
 INSERT INTO FKTABLE VALUES (NULL, 1);
 -- Insert a failed row into FK TABLE
@@ -351,6 +379,43 @@ INSERT INTO FKTABLE VALUES (1, NULL);
 ALTER TABLE FKTABLE ADD FOREIGN KEY(ftest1, ftest2) REFERENCES PKTABLE MATCH FULL;
 ERROR:  insert or update on table "fktable" violates foreign key constraint "fktable_ftest1_ftest2_fkey"
 DETAIL:  MATCH FULL does not allow mixing of null and nonnull key values.
+-- Modifying other attributes of a constraint should not affect its enforceability, and vice versa
+ALTER TABLE FKTABLE ADD CONSTRAINT fk_con FOREIGN KEY(ftest1, ftest2) REFERENCES PKTABLE NOT VALID NOT ENFORCED;
+ALTER TABLE FKTABLE ALTER CONSTRAINT fk_con DEFERRABLE INITIALLY DEFERRED;
+SELECT condeferrable, condeferred, conenforced, convalidated
+FROM pg_constraint WHERE conname = 'fk_con';
+ condeferrable | condeferred | conenforced | convalidated 
+---------------+-------------+-------------+--------------
+ t             | t           | f           | f
+(1 row)
+
+ALTER TABLE FKTABLE ALTER CONSTRAINT fk_con NOT ENFORCED;
+SELECT condeferrable, condeferred, conenforced, convalidated
+FROM pg_constraint WHERE conname = 'fk_con';
+ condeferrable | condeferred | conenforced | convalidated 
+---------------+-------------+-------------+--------------
+ t             | t           | f           | f
+(1 row)
+
+-- Enforceability also changes the validate state, as data validation will be
+-- performed during this transformation.
+ALTER TABLE FKTABLE ALTER CONSTRAINT fk_con ENFORCED;
+SELECT condeferrable, condeferred, conenforced, convalidated
+FROM pg_constraint WHERE conname = 'fk_con';
+ condeferrable | condeferred | conenforced | convalidated 
+---------------+-------------+-------------+--------------
+ t             | t           | t           | t
+(1 row)
+
+-- Can change enforceability and deferrability together
+ALTER TABLE FKTABLE ALTER CONSTRAINT fk_con NOT ENFORCED NOT DEFERRABLE;
+SELECT condeferrable, condeferred, conenforced, convalidated
+FROM pg_constraint WHERE conname = 'fk_con';
+ condeferrable | condeferred | conenforced | convalidated 
+---------------+-------------+-------------+--------------
+ f             | f           | f           | f
+(1 row)
+
 DROP TABLE FKTABLE;
 DROP TABLE PKTABLE;
 -- MATCH SIMPLE
@@ -1276,6 +1341,13 @@ INSERT INTO fktable VALUES (0, 20);
 ERROR:  insert or update on table "fktable" violates foreign key constraint "fktable_fk_fkey"
 DETAIL:  Key (fk)=(20) is not present in table "pktable".
 COMMIT;
+ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey NOT ENFORCED;
+BEGIN;
+-- doesn't match FK, but no error.
+UPDATE pktable SET id = 10 WHERE id = 5;
+-- doesn't match PK, but no error.
+INSERT INTO fktable VALUES (0, 20);
+ROLLBACK;
 -- try additional syntax
 ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey NOT DEFERRABLE;
 -- illegal options
@@ -1289,6 +1361,14 @@ ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey NOT VALID;
 ERROR:  FOREIGN KEY constraints cannot be marked NOT VALID
 LINE 1: ...ER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey NOT VALID;
                                                              ^
+ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey ENFORCED NOT ENFORCED;
+ERROR:  conflicting constraint properties
+LINE 1: ...fktable ALTER CONSTRAINT fktable_fk_fkey ENFORCED NOT ENFORC...
+                                                             ^
+CREATE TEMP TABLE fktable2 (fk int references pktable ENFORCED NOT ENFORCED);
+ERROR:  multiple ENFORCED/NOT ENFORCED clauses not allowed
+LINE 1: ...ABLE fktable2 (fk int references pktable ENFORCED NOT ENFORC...
+                                                             ^
 -- test order of firing of FK triggers when several RI-induced changes need to
 -- be made to the same row.  This was broken by subtransaction-related
 -- changes in 8.0.
@@ -1586,10 +1666,14 @@ ALTER TABLE fk_partitioned_fk DROP COLUMN fdrop1;
 CREATE TABLE fk_partitioned_fk_1 (fdrop1 int, fdrop2 int, a int, fdrop3 int, b int);
 ALTER TABLE fk_partitioned_fk_1 DROP COLUMN fdrop1, DROP COLUMN fdrop2, DROP COLUMN fdrop3;
 ALTER TABLE fk_partitioned_fk ATTACH PARTITION fk_partitioned_fk_1 FOR VALUES FROM (0,0) TO (1000,1000);
-ALTER TABLE fk_partitioned_fk ADD FOREIGN KEY (a, b) REFERENCES fk_notpartitioned_pk;
+ALTER TABLE fk_partitioned_fk ADD CONSTRAINT fk_partitioned_fk_a_b_fkey FOREIGN KEY (a, b)
+	REFERENCES fk_notpartitioned_pk NOT ENFORCED;
 CREATE TABLE fk_partitioned_fk_2 (b int, fdrop1 int, fdrop2 int, a int);
 ALTER TABLE fk_partitioned_fk_2 DROP COLUMN fdrop1, DROP COLUMN fdrop2;
+ALTER TABLE fk_partitioned_fk_2 ADD CONSTRAINT fk_partitioned_fk_a_b_fkey FOREIGN KEY (a, b)
+	REFERENCES fk_notpartitioned_pk NOT ENFORCED;
 ALTER TABLE fk_partitioned_fk ATTACH PARTITION fk_partitioned_fk_2 FOR VALUES FROM (1000,1000) TO (2000,2000);
+ALTER TABLE fk_partitioned_fk ALTER CONSTRAINT fk_partitioned_fk_a_b_fkey ENFORCED;
 CREATE TABLE fk_partitioned_fk_3 (fdrop1 int, fdrop2 int, fdrop3 int, fdrop4 int, b int, a int)
   PARTITION BY HASH (a);
 ALTER TABLE fk_partitioned_fk_3 DROP COLUMN fdrop1, DROP COLUMN fdrop2,
@@ -1665,6 +1749,67 @@ Indexes:
 Referenced by:
     TABLE "fk_partitioned_fk" CONSTRAINT "fk_partitioned_fk_a_b_fkey" FOREIGN KEY (a, b) REFERENCES fk_notpartitioned_pk(a, b)
 
+-- Check the exsting FK trigger
+SELECT conname, tgrelid::regclass as tgrel, regexp_replace(tgname, '[0-9]+', 'N') as tgname, tgtype
+FROM pg_trigger t JOIN pg_constraint c ON (t.tgconstraint = c.oid)
+WHERE tgrelid IN (SELECT relid FROM pg_partition_tree('fk_partitioned_fk'::regclass)
+				  UNION ALL SELECT 'fk_notpartitioned_pk'::regclass)
+ORDER BY tgrelid, tgtype;
+          conname           |         tgrel         |          tgname          | tgtype 
+----------------------------+-----------------------+--------------------------+--------
+ fk_partitioned_fk_a_b_fkey | fk_notpartitioned_pk  | RI_ConstraintTrigger_a_N |      9
+ fk_partitioned_fk_a_b_fkey | fk_notpartitioned_pk  | RI_ConstraintTrigger_a_N |     17
+ fk_partitioned_fk_a_b_fkey | fk_partitioned_fk     | RI_ConstraintTrigger_c_N |      5
+ fk_partitioned_fk_a_b_fkey | fk_partitioned_fk     | RI_ConstraintTrigger_c_N |     17
+ fk_partitioned_fk_a_b_fkey | fk_partitioned_fk_1   | RI_ConstraintTrigger_c_N |      5
+ fk_partitioned_fk_a_b_fkey | fk_partitioned_fk_1   | RI_ConstraintTrigger_c_N |     17
+ fk_partitioned_fk_a_b_fkey | fk_partitioned_fk_2   | RI_ConstraintTrigger_c_N |      5
+ fk_partitioned_fk_a_b_fkey | fk_partitioned_fk_2   | RI_ConstraintTrigger_c_N |     17
+ fk_partitioned_fk_a_b_fkey | fk_partitioned_fk_3   | RI_ConstraintTrigger_c_N |      5
+ fk_partitioned_fk_a_b_fkey | fk_partitioned_fk_3   | RI_ConstraintTrigger_c_N |     17
+ fk_partitioned_fk_a_b_fkey | fk_partitioned_fk_3_0 | RI_ConstraintTrigger_c_N |      5
+ fk_partitioned_fk_a_b_fkey | fk_partitioned_fk_3_0 | RI_ConstraintTrigger_c_N |     17
+ fk_partitioned_fk_a_b_fkey | fk_partitioned_fk_3_1 | RI_ConstraintTrigger_c_N |      5
+ fk_partitioned_fk_a_b_fkey | fk_partitioned_fk_3_1 | RI_ConstraintTrigger_c_N |     17
+(14 rows)
+
+ALTER TABLE fk_partitioned_fk ALTER CONSTRAINT fk_partitioned_fk_a_b_fkey NOT ENFORCED;
+-- No triggers
+SELECT conname, tgrelid::regclass as tgrel, regexp_replace(tgname, '[0-9]+', 'N') as tgname, tgtype
+FROM pg_trigger t JOIN pg_constraint c ON (t.tgconstraint = c.oid)
+WHERE tgrelid IN (SELECT relid FROM pg_partition_tree('fk_partitioned_fk'::regclass)
+				  UNION ALL SELECT 'fk_notpartitioned_pk'::regclass)
+ORDER BY tgrelid, tgtype;
+ conname | tgrel | tgname | tgtype 
+---------+-------+--------+--------
+(0 rows)
+
+-- Changing it back to ENFORCED will recreate the necessary triggers.
+ALTER TABLE fk_partitioned_fk ALTER CONSTRAINT fk_partitioned_fk_a_b_fkey ENFORCED;
+-- Should be exactly the same number of triggers found as before
+SELECT conname, tgrelid::regclass as tgrel, regexp_replace(tgname, '[0-9]+', 'N') as tgname, tgtype
+FROM pg_trigger t JOIN pg_constraint c ON (t.tgconstraint = c.oid)
+WHERE tgrelid IN (SELECT relid FROM pg_partition_tree('fk_partitioned_fk'::regclass)
+				  UNION ALL SELECT 'fk_notpartitioned_pk'::regclass)
+ORDER BY tgrelid, tgtype;
+          conname           |         tgrel         |          tgname          | tgtype 
+----------------------------+-----------------------+--------------------------+--------
+ fk_partitioned_fk_a_b_fkey | fk_notpartitioned_pk  | RI_ConstraintTrigger_a_N |      9
+ fk_partitioned_fk_a_b_fkey | fk_notpartitioned_pk  | RI_ConstraintTrigger_a_N |     17
+ fk_partitioned_fk_a_b_fkey | fk_partitioned_fk     | RI_ConstraintTrigger_c_N |      5
+ fk_partitioned_fk_a_b_fkey | fk_partitioned_fk     | RI_ConstraintTrigger_c_N |     17
+ fk_partitioned_fk_a_b_fkey | fk_partitioned_fk_1   | RI_ConstraintTrigger_c_N |      5
+ fk_partitioned_fk_a_b_fkey | fk_partitioned_fk_1   | RI_ConstraintTrigger_c_N |     17
+ fk_partitioned_fk_a_b_fkey | fk_partitioned_fk_2   | RI_ConstraintTrigger_c_N |      5
+ fk_partitioned_fk_a_b_fkey | fk_partitioned_fk_2   | RI_ConstraintTrigger_c_N |     17
+ fk_partitioned_fk_a_b_fkey | fk_partitioned_fk_3   | RI_ConstraintTrigger_c_N |      5
+ fk_partitioned_fk_a_b_fkey | fk_partitioned_fk_3   | RI_ConstraintTrigger_c_N |     17
+ fk_partitioned_fk_a_b_fkey | fk_partitioned_fk_3_0 | RI_ConstraintTrigger_c_N |      5
+ fk_partitioned_fk_a_b_fkey | fk_partitioned_fk_3_0 | RI_ConstraintTrigger_c_N |     17
+ fk_partitioned_fk_a_b_fkey | fk_partitioned_fk_3_1 | RI_ConstraintTrigger_c_N |      5
+ fk_partitioned_fk_a_b_fkey | fk_partitioned_fk_3_1 | RI_ConstraintTrigger_c_N |     17
+(14 rows)
+
 ALTER TABLE fk_partitioned_fk DROP CONSTRAINT fk_partitioned_fk_a_b_fkey;
 -- done.
 DROP TABLE fk_notpartitioned_pk, fk_partitioned_fk;
@@ -1962,6 +2107,43 @@ Partition of: fk_partitioned_fk FOR VALUES IN (1500, 1502)
 Foreign-key constraints:
     TABLE "fk_partitioned_fk" CONSTRAINT "fk_partitioned_fk_a_b_fkey" FOREIGN KEY (a, b) REFERENCES fk_notpartitioned_pk(a, b) ON UPDATE CASCADE ON DELETE CASCADE
 
+DROP TABLE fk_partitioned_fk_2;
+CREATE TABLE fk_partitioned_fk_2 (b int, a int,
+	CONSTRAINT fk_part_con FOREIGN KEY (a, b) REFERENCES fk_notpartitioned_pk ON UPDATE CASCADE ON DELETE CASCADE NOT ENFORCED);
+-- fail -- cannot merge constraints with different enforceability.
+ALTER TABLE fk_partitioned_fk ATTACH PARTITION fk_partitioned_fk_2 FOR VALUES IN (1500,1502);
+ERROR:  constraint "fk_partitioned_fk_a_b_fkey" enforceability conflicts with constraint "fk_part_con" on relation "fk_partitioned_fk_2"
+-- If the constraint is modified to match the enforceability of the parent, it will work.
+BEGIN;
+-- change child constraint
+ALTER TABLE fk_partitioned_fk_2 ALTER CONSTRAINT fk_part_con ENFORCED;
+ALTER TABLE fk_partitioned_fk ATTACH PARTITION fk_partitioned_fk_2 FOR VALUES IN (1500,1502);
+\d fk_partitioned_fk_2
+        Table "public.fk_partitioned_fk_2"
+ Column |  Type   | Collation | Nullable | Default 
+--------+---------+-----------+----------+---------
+ b      | integer |           |          | 
+ a      | integer |           |          | 
+Partition of: fk_partitioned_fk FOR VALUES IN (1500, 1502)
+Foreign-key constraints:
+    TABLE "fk_partitioned_fk" CONSTRAINT "fk_partitioned_fk_a_b_fkey" FOREIGN KEY (a, b) REFERENCES fk_notpartitioned_pk(a, b) ON UPDATE CASCADE ON DELETE CASCADE
+
+ROLLBACK;
+BEGIN;
+-- or change parent constraint
+ALTER TABLE fk_partitioned_fk ALTER CONSTRAINT fk_partitioned_fk_a_b_fkey NOT ENFORCED;
+ALTER TABLE fk_partitioned_fk ATTACH PARTITION fk_partitioned_fk_2 FOR VALUES IN (1500,1502);
+\d fk_partitioned_fk_2
+        Table "public.fk_partitioned_fk_2"
+ Column |  Type   | Collation | Nullable | Default 
+--------+---------+-----------+----------+---------
+ b      | integer |           |          | 
+ a      | integer |           |          | 
+Partition of: fk_partitioned_fk FOR VALUES IN (1500, 1502)
+Foreign-key constraints:
+    TABLE "fk_partitioned_fk" CONSTRAINT "fk_partitioned_fk_a_b_fkey" FOREIGN KEY (a, b) REFERENCES fk_notpartitioned_pk(a, b) ON UPDATE CASCADE ON DELETE CASCADE NOT ENFORCED
+
+ROLLBACK;
 DROP TABLE fk_partitioned_fk_2;
 CREATE TABLE fk_partitioned_fk_4 (a int, b int, FOREIGN KEY (a, b) REFERENCES fk_notpartitioned_pk(a, b) ON UPDATE CASCADE ON DELETE CASCADE) PARTITION BY RANGE (b, a);
 CREATE TABLE fk_partitioned_fk_4_1 PARTITION OF fk_partitioned_fk_4 FOR VALUES FROM (1,1) TO (100,100);

src/test/regress/expected/inherit.out

@@ -1332,6 +1332,13 @@ NOTICE:  merging constraint "inh_check_constraint5" with inherited definition
 alter table p1 add constraint inh_check_constraint6 check (f1 < 10) not enforced;
 alter table p1_c1 add constraint inh_check_constraint6 check (f1 < 10) enforced;
 NOTICE:  merging constraint "inh_check_constraint6" with inherited definition
+alter table p1_c1 add constraint inh_check_constraint9 check (f1 < 10) not valid enforced;
+alter table p1 add constraint inh_check_constraint9 check (f1 < 10) not enforced;
+NOTICE:  merging constraint "inh_check_constraint9" with inherited definition
+-- the not-valid state of the child constraint will be ignored here.
+alter table p1 add constraint inh_check_constraint10 check (f1 < 10) not enforced;
+alter table p1_c1 add constraint inh_check_constraint10 check (f1 < 10) not valid enforced;
+NOTICE:  merging constraint "inh_check_constraint10" with inherited definition
 create table p1_c2(f1 int constraint inh_check_constraint4 check (f1 < 10)) inherits(p1);
 NOTICE:  merging column "f1" with inherited definition
 NOTICE:  merging constraint "inh_check_constraint4" with inherited definition
@@ -1356,39 +1363,47 @@ ERROR:  constraint "inh_check_constraint6" conflicts with NOT ENFORCED constrain
 select conrelid::regclass::text as relname, conname, conislocal, coninhcount, conenforced, convalidated
 from pg_constraint where conname like 'inh\_check\_constraint%'
 order by 1, 2;
- relname |        conname        | conislocal | coninhcount | conenforced | convalidated 
----------+-----------------------+------------+-------------+-------------+--------------
- p1      | inh_check_constraint1 | t          |           0 | t           | t
- p1      | inh_check_constraint2 | t          |           0 | t           | t
- p1      | inh_check_constraint3 | t          |           0 | f           | f
- p1      | inh_check_constraint4 | t          |           0 | f           | f
- p1      | inh_check_constraint5 | t          |           0 | f           | f
- p1      | inh_check_constraint6 | t          |           0 | f           | f
- p1      | inh_check_constraint8 | t          |           0 | t           | t
- p1_c1   | inh_check_constraint1 | t          |           1 | t           | t
- p1_c1   | inh_check_constraint2 | t          |           1 | t           | t
- p1_c1   | inh_check_constraint3 | t          |           1 | f           | f
- p1_c1   | inh_check_constraint4 | t          |           1 | f           | f
- p1_c1   | inh_check_constraint5 | t          |           1 | t           | t
- p1_c1   | inh_check_constraint6 | t          |           1 | t           | t
- p1_c1   | inh_check_constraint7 | t          |           0 | f           | f
- p1_c1   | inh_check_constraint8 | f          |           1 | t           | t
- p1_c2   | inh_check_constraint1 | f          |           1 | t           | t
- p1_c2   | inh_check_constraint2 | f          |           1 | t           | t
- p1_c2   | inh_check_constraint3 | f          |           1 | f           | f
- p1_c2   | inh_check_constraint4 | t          |           1 | t           | t
- p1_c2   | inh_check_constraint5 | f          |           1 | f           | f
- p1_c2   | inh_check_constraint6 | f          |           1 | f           | f
- p1_c2   | inh_check_constraint8 | f          |           1 | t           | t
- p1_c3   | inh_check_constraint1 | f          |           2 | t           | t
- p1_c3   | inh_check_constraint2 | f          |           2 | t           | t
- p1_c3   | inh_check_constraint3 | f          |           2 | f           | f
- p1_c3   | inh_check_constraint4 | f          |           2 | f           | f
- p1_c3   | inh_check_constraint5 | f          |           2 | t           | t
- p1_c3   | inh_check_constraint6 | f          |           2 | t           | t
- p1_c3   | inh_check_constraint7 | f          |           1 | f           | f
- p1_c3   | inh_check_constraint8 | f          |           2 | t           | t
-(30 rows)
+ relname |        conname         | conislocal | coninhcount | conenforced | convalidated 
+---------+------------------------+------------+-------------+-------------+--------------
+ p1      | inh_check_constraint1  | t          |           0 | t           | t
+ p1      | inh_check_constraint10 | t          |           0 | f           | f
+ p1      | inh_check_constraint2  | t          |           0 | t           | t
+ p1      | inh_check_constraint3  | t          |           0 | f           | f
+ p1      | inh_check_constraint4  | t          |           0 | f           | f
+ p1      | inh_check_constraint5  | t          |           0 | f           | f
+ p1      | inh_check_constraint6  | t          |           0 | f           | f
+ p1      | inh_check_constraint8  | t          |           0 | t           | t
+ p1      | inh_check_constraint9  | t          |           0 | f           | f
+ p1_c1   | inh_check_constraint1  | t          |           1 | t           | t
+ p1_c1   | inh_check_constraint10 | t          |           1 | t           | t
+ p1_c1   | inh_check_constraint2  | t          |           1 | t           | t
+ p1_c1   | inh_check_constraint3  | t          |           1 | f           | f
+ p1_c1   | inh_check_constraint4  | t          |           1 | f           | f
+ p1_c1   | inh_check_constraint5  | t          |           1 | t           | t
+ p1_c1   | inh_check_constraint6  | t          |           1 | t           | t
+ p1_c1   | inh_check_constraint7  | t          |           0 | f           | f
+ p1_c1   | inh_check_constraint8  | f          |           1 | t           | t
+ p1_c1   | inh_check_constraint9  | t          |           1 | t           | f
+ p1_c2   | inh_check_constraint1  | f          |           1 | t           | t
+ p1_c2   | inh_check_constraint10 | f          |           1 | f           | f
+ p1_c2   | inh_check_constraint2  | f          |           1 | t           | t
+ p1_c2   | inh_check_constraint3  | f          |           1 | f           | f
+ p1_c2   | inh_check_constraint4  | t          |           1 | t           | t
+ p1_c2   | inh_check_constraint5  | f          |           1 | f           | f
+ p1_c2   | inh_check_constraint6  | f          |           1 | f           | f
+ p1_c2   | inh_check_constraint8  | f          |           1 | t           | t
+ p1_c2   | inh_check_constraint9  | f          |           1 | f           | f
+ p1_c3   | inh_check_constraint1  | f          |           2 | t           | t
+ p1_c3   | inh_check_constraint10 | f          |           2 | t           | t
+ p1_c3   | inh_check_constraint2  | f          |           2 | t           | t
+ p1_c3   | inh_check_constraint3  | f          |           2 | f           | f
+ p1_c3   | inh_check_constraint4  | f          |           2 | f           | f
+ p1_c3   | inh_check_constraint5  | f          |           2 | t           | t
+ p1_c3   | inh_check_constraint6  | f          |           2 | t           | t
+ p1_c3   | inh_check_constraint7  | f          |           1 | f           | f
+ p1_c3   | inh_check_constraint8  | f          |           2 | t           | t
+ p1_c3   | inh_check_constraint9  | f          |           2 | t           | t
+(38 rows)
 
 drop table p1 cascade;
 NOTICE:  drop cascades to 3 other objects

src/test/regress/sql/foreign_key.sql

@@ -2,23 +2,46 @@
 -- FOREIGN KEY
 --
 
--- MATCH FULL
+-- NOT ENFORCED
 --
 -- First test, check and cascade
 --
 CREATE TABLE PKTABLE ( ptest1 int PRIMARY KEY, ptest2 text );
-CREATE TABLE FKTABLE ( ftest1 int REFERENCES PKTABLE MATCH FULL ON DELETE CASCADE ON UPDATE CASCADE, ftest2 int );
+CREATE TABLE FKTABLE ( ftest1 int CONSTRAINT fktable_ftest1_fkey REFERENCES PKTABLE MATCH FULL ON DELETE CASCADE ON UPDATE CASCADE NOT ENFORCED,
+					   ftest2 int );
 
--- Insert test data into PKTABLE
+-- Inserting into the foreign key table will not result in an error, even if
+-- there is no matching key in the referenced table.
+INSERT INTO FKTABLE VALUES (1, 2);
+INSERT INTO FKTABLE VALUES (2, 3);
+
+-- Check FKTABLE
+SELECT * FROM FKTABLE;
+
+-- Reverting it back to ENFORCED will result in failure because constraint validation will be triggered,
+-- as it was previously in a valid state.
+ALTER TABLE FKTABLE ALTER CONSTRAINT fktable_ftest1_fkey ENFORCED;
+
+-- Insert referenced data that satisfies the constraint, then attempt to
+-- change it.
 INSERT INTO PKTABLE VALUES (1, 'Test1');
 INSERT INTO PKTABLE VALUES (2, 'Test2');
+ALTER TABLE FKTABLE ALTER CONSTRAINT fktable_ftest1_fkey ENFORCED;
+
+-- Any further inserts will fail due to the enforcement.
+INSERT INTO FKTABLE VALUES (3, 4);
+
+--
+-- MATCH FULL
+--
+-- First test, check and cascade
+--
+-- Insert test data into PKTABLE
 INSERT INTO PKTABLE VALUES (3, 'Test3');
 INSERT INTO PKTABLE VALUES (4, 'Test4');
 INSERT INTO PKTABLE VALUES (5, 'Test5');
 
 -- Insert successful rows into FK TABLE
-INSERT INTO FKTABLE VALUES (1, 2);
-INSERT INTO FKTABLE VALUES (2, 3);
 INSERT INTO FKTABLE VALUES (3, 4);
 INSERT INTO FKTABLE VALUES (NULL, 1);
 
@@ -230,6 +253,27 @@ INSERT INTO FKTABLE VALUES (1, NULL);
 
 ALTER TABLE FKTABLE ADD FOREIGN KEY(ftest1, ftest2) REFERENCES PKTABLE MATCH FULL;
 
+-- Modifying other attributes of a constraint should not affect its enforceability, and vice versa
+ALTER TABLE FKTABLE ADD CONSTRAINT fk_con FOREIGN KEY(ftest1, ftest2) REFERENCES PKTABLE NOT VALID NOT ENFORCED;
+ALTER TABLE FKTABLE ALTER CONSTRAINT fk_con DEFERRABLE INITIALLY DEFERRED;
+SELECT condeferrable, condeferred, conenforced, convalidated
+FROM pg_constraint WHERE conname = 'fk_con';
+
+ALTER TABLE FKTABLE ALTER CONSTRAINT fk_con NOT ENFORCED;
+SELECT condeferrable, condeferred, conenforced, convalidated
+FROM pg_constraint WHERE conname = 'fk_con';
+
+-- Enforceability also changes the validate state, as data validation will be
+-- performed during this transformation.
+ALTER TABLE FKTABLE ALTER CONSTRAINT fk_con ENFORCED;
+SELECT condeferrable, condeferred, conenforced, convalidated
+FROM pg_constraint WHERE conname = 'fk_con';
+
+-- Can change enforceability and deferrability together
+ALTER TABLE FKTABLE ALTER CONSTRAINT fk_con NOT ENFORCED NOT DEFERRABLE;
+SELECT condeferrable, condeferred, conenforced, convalidated
+FROM pg_constraint WHERE conname = 'fk_con';
+
 DROP TABLE FKTABLE;
 DROP TABLE PKTABLE;
 
@@ -968,12 +1012,25 @@ INSERT INTO fktable VALUES (0, 20);
 
 COMMIT;
 
+ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey NOT ENFORCED;
+
+BEGIN;
+
+-- doesn't match FK, but no error.
+UPDATE pktable SET id = 10 WHERE id = 5;
+-- doesn't match PK, but no error.
+INSERT INTO fktable VALUES (0, 20);
+
+ROLLBACK;
+
 -- try additional syntax
 ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey NOT DEFERRABLE;
 -- illegal options
 ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey NOT DEFERRABLE INITIALLY DEFERRED;
 ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey NO INHERIT;
 ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey NOT VALID;
+ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey ENFORCED NOT ENFORCED;
+CREATE TEMP TABLE fktable2 (fk int references pktable ENFORCED NOT ENFORCED);
 
 -- test order of firing of FK triggers when several RI-induced changes need to
 -- be made to the same row.  This was broken by subtransaction-related
@@ -1184,11 +1241,14 @@ ALTER TABLE fk_partitioned_fk DROP COLUMN fdrop1;
 CREATE TABLE fk_partitioned_fk_1 (fdrop1 int, fdrop2 int, a int, fdrop3 int, b int);
 ALTER TABLE fk_partitioned_fk_1 DROP COLUMN fdrop1, DROP COLUMN fdrop2, DROP COLUMN fdrop3;
 ALTER TABLE fk_partitioned_fk ATTACH PARTITION fk_partitioned_fk_1 FOR VALUES FROM (0,0) TO (1000,1000);
-ALTER TABLE fk_partitioned_fk ADD FOREIGN KEY (a, b) REFERENCES fk_notpartitioned_pk;
+ALTER TABLE fk_partitioned_fk ADD CONSTRAINT fk_partitioned_fk_a_b_fkey FOREIGN KEY (a, b)
+	REFERENCES fk_notpartitioned_pk NOT ENFORCED;
 CREATE TABLE fk_partitioned_fk_2 (b int, fdrop1 int, fdrop2 int, a int);
 ALTER TABLE fk_partitioned_fk_2 DROP COLUMN fdrop1, DROP COLUMN fdrop2;
+ALTER TABLE fk_partitioned_fk_2 ADD CONSTRAINT fk_partitioned_fk_a_b_fkey FOREIGN KEY (a, b)
+	REFERENCES fk_notpartitioned_pk NOT ENFORCED;
 ALTER TABLE fk_partitioned_fk ATTACH PARTITION fk_partitioned_fk_2 FOR VALUES FROM (1000,1000) TO (2000,2000);
-
+ALTER TABLE fk_partitioned_fk ALTER CONSTRAINT fk_partitioned_fk_a_b_fkey ENFORCED;
 CREATE TABLE fk_partitioned_fk_3 (fdrop1 int, fdrop2 int, fdrop3 int, fdrop4 int, b int, a int)
   PARTITION BY HASH (a);
 ALTER TABLE fk_partitioned_fk_3 DROP COLUMN fdrop1, DROP COLUMN fdrop2,
@@ -1234,6 +1294,32 @@ UPDATE fk_notpartitioned_pk SET b = 1502 WHERE a = 1500;
 UPDATE fk_notpartitioned_pk SET b = 2504 WHERE a = 2500;
 -- check psql behavior
 \d fk_notpartitioned_pk
+
+-- Check the exsting FK trigger
+SELECT conname, tgrelid::regclass as tgrel, regexp_replace(tgname, '[0-9]+', 'N') as tgname, tgtype
+FROM pg_trigger t JOIN pg_constraint c ON (t.tgconstraint = c.oid)
+WHERE tgrelid IN (SELECT relid FROM pg_partition_tree('fk_partitioned_fk'::regclass)
+				  UNION ALL SELECT 'fk_notpartitioned_pk'::regclass)
+ORDER BY tgrelid, tgtype;
+
+ALTER TABLE fk_partitioned_fk ALTER CONSTRAINT fk_partitioned_fk_a_b_fkey NOT ENFORCED;
+-- No triggers
+SELECT conname, tgrelid::regclass as tgrel, regexp_replace(tgname, '[0-9]+', 'N') as tgname, tgtype
+FROM pg_trigger t JOIN pg_constraint c ON (t.tgconstraint = c.oid)
+WHERE tgrelid IN (SELECT relid FROM pg_partition_tree('fk_partitioned_fk'::regclass)
+				  UNION ALL SELECT 'fk_notpartitioned_pk'::regclass)
+ORDER BY tgrelid, tgtype;
+
+-- Changing it back to ENFORCED will recreate the necessary triggers.
+ALTER TABLE fk_partitioned_fk ALTER CONSTRAINT fk_partitioned_fk_a_b_fkey ENFORCED;
+
+-- Should be exactly the same number of triggers found as before
+SELECT conname, tgrelid::regclass as tgrel, regexp_replace(tgname, '[0-9]+', 'N') as tgname, tgtype
+FROM pg_trigger t JOIN pg_constraint c ON (t.tgconstraint = c.oid)
+WHERE tgrelid IN (SELECT relid FROM pg_partition_tree('fk_partitioned_fk'::regclass)
+				  UNION ALL SELECT 'fk_notpartitioned_pk'::regclass)
+ORDER BY tgrelid, tgtype;
+
 ALTER TABLE fk_partitioned_fk DROP CONSTRAINT fk_partitioned_fk_a_b_fkey;
 -- done.
 DROP TABLE fk_notpartitioned_pk, fk_partitioned_fk;
@@ -1441,6 +1527,25 @@ ALTER TABLE fk_partitioned_fk ATTACH PARTITION fk_partitioned_fk_2 FOR VALUES IN
 \d fk_partitioned_fk_2
 DROP TABLE fk_partitioned_fk_2;
 
+CREATE TABLE fk_partitioned_fk_2 (b int, a int,
+	CONSTRAINT fk_part_con FOREIGN KEY (a, b) REFERENCES fk_notpartitioned_pk ON UPDATE CASCADE ON DELETE CASCADE NOT ENFORCED);
+-- fail -- cannot merge constraints with different enforceability.
+ALTER TABLE fk_partitioned_fk ATTACH PARTITION fk_partitioned_fk_2 FOR VALUES IN (1500,1502);
+-- If the constraint is modified to match the enforceability of the parent, it will work.
+BEGIN;
+-- change child constraint
+ALTER TABLE fk_partitioned_fk_2 ALTER CONSTRAINT fk_part_con ENFORCED;
+ALTER TABLE fk_partitioned_fk ATTACH PARTITION fk_partitioned_fk_2 FOR VALUES IN (1500,1502);
+\d fk_partitioned_fk_2
+ROLLBACK;
+BEGIN;
+-- or change parent constraint
+ALTER TABLE fk_partitioned_fk ALTER CONSTRAINT fk_partitioned_fk_a_b_fkey NOT ENFORCED;
+ALTER TABLE fk_partitioned_fk ATTACH PARTITION fk_partitioned_fk_2 FOR VALUES IN (1500,1502);
+\d fk_partitioned_fk_2
+ROLLBACK;
+DROP TABLE fk_partitioned_fk_2;
+
 CREATE TABLE fk_partitioned_fk_4 (a int, b int, FOREIGN KEY (a, b) REFERENCES fk_notpartitioned_pk(a, b) ON UPDATE CASCADE ON DELETE CASCADE) PARTITION BY RANGE (b, a);
 CREATE TABLE fk_partitioned_fk_4_1 PARTITION OF fk_partitioned_fk_4 FOR VALUES FROM (1,1) TO (100,100);
 CREATE TABLE fk_partitioned_fk_4_2 (a int, b int, FOREIGN KEY (a, b) REFERENCES fk_notpartitioned_pk(a, b) ON UPDATE SET NULL);

src/test/regress/sql/inherit.sql

@@ -481,6 +481,13 @@ alter table p1 add constraint inh_check_constraint5 check (f1 < 10) not enforced
 alter table p1 add constraint inh_check_constraint6 check (f1 < 10) not enforced;
 alter table p1_c1 add constraint inh_check_constraint6 check (f1 < 10) enforced;
 
+alter table p1_c1 add constraint inh_check_constraint9 check (f1 < 10) not valid enforced;
+alter table p1 add constraint inh_check_constraint9 check (f1 < 10) not enforced;
+
+-- the not-valid state of the child constraint will be ignored here.
+alter table p1 add constraint inh_check_constraint10 check (f1 < 10) not enforced;
+alter table p1_c1 add constraint inh_check_constraint10 check (f1 < 10) not valid enforced;
+
 create table p1_c2(f1 int constraint inh_check_constraint4 check (f1 < 10)) inherits(p1);
 
 -- but reverse is not allowed