Add temporal FOREIGN KEY contraints

Add PERIOD clause to foreign key constraint definitions.  This is
supported for range and multirange types.  Temporal foreign keys check
for range containment instead of equality.

This feature matches the behavior of the SQL standard temporal foreign
keys, but it works on PostgreSQL's native ranges instead of SQL's
"periods", which don't exist in PostgreSQL (yet).

Reference actions ON {UPDATE,DELETE} {CASCADE,SET NULL,SET DEFAULT}
are not supported yet.

Author: Paul A. Jungwirth <pj@illuminatedcomputing.com>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: jian he <jian.universality@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/CA+renyUApHgSZF9-nd-a0+OPGharLQLO=mDHcY4_qQ0+noCUVg@mail.gmail.com

2 files changed, 204 insertions, 53 deletions

diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index 7b20d103c86..d9016ef487b 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -2185,7 +2185,7 @@ ComputeIndexAttrs(IndexInfo *indexInfo,
 				strat = RTOverlapStrategyNumber;
 			else
 				strat = RTEqualStrategyNumber;
-			GetOperatorFromWellKnownStrategy(opclassOids[attn], atttype,
+			GetOperatorFromWellKnownStrategy(opclassOids[attn], InvalidOid,
 											 &opid, &strat);
 			indexInfo->ii_ExclusionOps[attn] = opid;
 			indexInfo->ii_ExclusionProcs[attn] = get_opcode(opid);
@@ -2425,7 +2425,7 @@ GetDefaultOpClass(Oid type_id, Oid am_id)
  * GetOperatorFromWellKnownStrategy
  *
  * opclass - the opclass to use
- * atttype - the type to ask about
+ * rhstype - the type for the right-hand side, or InvalidOid to use the type of the given opclass.
  * opid - holds the operator we found
  * strat - holds the input and output strategy number
  *
@@ -2438,14 +2438,14 @@ GetDefaultOpClass(Oid type_id, Oid am_id)
  * InvalidStrategy.
  */
 void
-GetOperatorFromWellKnownStrategy(Oid opclass, Oid atttype,
+GetOperatorFromWellKnownStrategy(Oid opclass, Oid rhstype,
 								 Oid *opid, StrategyNumber *strat)
 {
 	Oid			opfamily;
 	Oid			opcintype;
 	StrategyNumber instrat = *strat;
 
-	Assert(instrat == RTEqualStrategyNumber || instrat == RTOverlapStrategyNumber);
+	Assert(instrat == RTEqualStrategyNumber || instrat == RTOverlapStrategyNumber || instrat == RTContainedByStrategyNumber);
 
 	*opid = InvalidOid;
 
@@ -2468,16 +2468,21 @@ GetOperatorFromWellKnownStrategy(Oid opclass, Oid atttype,
 
 			ereport(ERROR,
 					errcode(ERRCODE_UNDEFINED_OBJECT),
-					instrat == RTEqualStrategyNumber ?
-					errmsg("could not identify an equality operator for type %s", format_type_be(atttype)) :
-					errmsg("could not identify an overlaps operator for type %s", format_type_be(atttype)),
+					instrat == RTEqualStrategyNumber ? errmsg("could not identify an equality operator for type %s", format_type_be(opcintype)) :
+					instrat == RTOverlapStrategyNumber ? errmsg("could not identify an overlaps operator for type %s", format_type_be(opcintype)) :
+					instrat == RTContainedByStrategyNumber ? errmsg("could not identify a contained-by operator for type %s", format_type_be(opcintype)) : 0,
 					errdetail("Could not translate strategy number %d for operator class \"%s\" for access method \"%s\".",
 							  instrat, NameStr(((Form_pg_opclass) GETSTRUCT(tuple))->opcname), "gist"));
-
-			ReleaseSysCache(tuple);
 		}
 
-		*opid = get_opfamily_member(opfamily, opcintype, opcintype, *strat);
+		/*
+		 * We parameterize rhstype so foreign keys can ask for a <@ operator
+		 * whose rhs matches the aggregate function. For example range_agg
+		 * returns anymultirange.
+		 */
+		if (!OidIsValid(rhstype))
+			rhstype = opcintype;
+		*opid = get_opfamily_member(opfamily, opcintype, rhstype, *strat);
 	}
 
 	if (!OidIsValid(*opid))
@@ -2490,9 +2495,9 @@ GetOperatorFromWellKnownStrategy(Oid opclass, Oid atttype,
 
 		ereport(ERROR,
 				errcode(ERRCODE_UNDEFINED_OBJECT),
-				instrat == RTEqualStrategyNumber ?
-				errmsg("could not identify an equality operator for type %s", format_type_be(atttype)) :
-				errmsg("could not identify an overlaps operator for type %s", format_type_be(atttype)),
+				instrat == RTEqualStrategyNumber ? errmsg("could not identify an equality operator for type %s", format_type_be(opcintype)) :
+				instrat == RTOverlapStrategyNumber ? errmsg("could not identify an overlaps operator for type %s", format_type_be(opcintype)) :
+				instrat == RTContainedByStrategyNumber ? errmsg("could not identify a contained-by operator for type %s", format_type_be(opcintype)) : 0,
 				errdetail("There is no suitable operator in operator family \"%s\" for access method \"%s\".",
 						  NameStr(((Form_pg_opfamily) GETSTRUCT(tuple))->opfname), "gist"));
 	}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 6c0c899210b..71740984f33 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -16,6 +16,7 @@
 
 #include "access/attmap.h"
 #include "access/genam.h"
+#include "access/gist.h"
 #include "access/heapam.h"
 #include "access/heapam_xlog.h"
 #include "access/multixact.h"
@@ -209,6 +210,7 @@ typedef struct NewConstraint
 	ConstrType	contype;		/* CHECK or FOREIGN */
 	Oid			refrelid;		/* PK rel, if FOREIGN */
 	Oid			refindid;		/* OID of PK's index, if FOREIGN */
+	bool		conwithperiod;	/* Whether the new FOREIGN KEY uses PERIOD */
 	Oid			conid;			/* OID of pg_constraint entry, if FOREIGN */
 	Node	   *qual;			/* Check expr or CONSTR_FOREIGN Constraint */
 	ExprState  *qualstate;		/* Execution state for CHECK expr */
@@ -384,16 +386,17 @@ static int	transformColumnNameList(Oid relId, List *colList,
 static int	transformFkeyGetPrimaryKey(Relation pkrel, Oid *indexOid,
 									   List **attnamelist,
 									   int16 *attnums, Oid *atttypids,
-									   Oid *opclasses);
+									   Oid *opclasses, bool *pk_has_without_overlaps);
 static Oid	transformFkeyCheckAttrs(Relation pkrel,
 									int numattrs, int16 *attnums,
-									Oid *opclasses);
+									bool with_period, Oid *opclasses,
+									bool *pk_has_without_overlaps);
 static void checkFkeyPermissions(Relation rel, int16 *attnums, int natts);
 static CoercionPathType findFkeyCast(Oid targetTypeId, Oid sourceTypeId,
 									 Oid *funcid);
 static void validateForeignKeyConstraint(char *conname,
 										 Relation rel, Relation pkrel,
-										 Oid pkindOid, Oid constraintOid);
+										 Oid pkindOid, Oid constraintOid, bool hasperiod);
 static void ATController(AlterTableStmt *parsetree,
 						 Relation rel, List *cmds, bool recurse, LOCKMODE lockmode,
 						 AlterTableUtilityContext *context);
@@ -506,7 +509,8 @@ static ObjectAddress addFkRecurseReferenced(List **wqueue, Constraint *fkconstra
 											Oid *pfeqoperators, Oid *ppeqoperators, Oid *ffeqoperators,
 											int numfkdelsetcols, int16 *fkdelsetcols,
 											bool old_check_ok,
-											Oid parentDelTrigger, Oid parentUpdTrigger);
+											Oid parentDelTrigger, Oid parentUpdTrigger,
+											bool with_period);
 static void validateFkOnDeleteSetColumns(int numfks, const int16 *fkattnums,
 										 int numfksetcols, const int16 *fksetcolsattnums,
 										 List *fksetcols);
@@ -516,7 +520,9 @@ static void addFkRecurseReferencing(List **wqueue, Constraint *fkconstraint,
 									Oid *pfeqoperators, Oid *ppeqoperators, Oid *ffeqoperators,
 									int numfkdelsetcols, int16 *fkdelsetcols,
 									bool old_check_ok, LOCKMODE lockmode,
-									Oid parentInsTrigger, Oid parentUpdTrigger);
+									Oid parentInsTrigger, Oid parentUpdTrigger,
+									bool with_period);
+
 static void CloneForeignKeyConstraints(List **wqueue, Relation parentRel,
 									   Relation partitionRel);
 static void CloneFkReferenced(Relation parentRel, Relation partitionRel);
@@ -5958,7 +5964,8 @@ ATRewriteTables(AlterTableStmt *parsetree, List **wqueue, LOCKMODE lockmode,
 
 				validateForeignKeyConstraint(fkconstraint->conname, rel, refrel,
 											 con->refindid,
-											 con->conid);
+											 con->conid,
+											 con->conwithperiod);
 
 				/*
 				 * No need to mark the constraint row as validated, we did
@@ -9809,6 +9816,8 @@ ATAddForeignKeyConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	Oid			ppeqoperators[INDEX_MAX_KEYS] = {0};
 	Oid			ffeqoperators[INDEX_MAX_KEYS] = {0};
 	int16		fkdelsetcols[INDEX_MAX_KEYS] = {0};
+	bool		with_period;
+	bool		pk_has_without_overlaps;
 	int			i;
 	int			numfks,
 				numpks,
@@ -9903,6 +9912,11 @@ ATAddForeignKeyConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	numfks = transformColumnNameList(RelationGetRelid(rel),
 									 fkconstraint->fk_attrs,
 									 fkattnum, fktypoid);
+	with_period = fkconstraint->fk_with_period || fkconstraint->pk_with_period;
+	if (with_period && !fkconstraint->fk_with_period)
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_FOREIGN_KEY),
+				errmsg("foreign key uses PERIOD on the referenced table but not the referencing table"));
 
 	numfkdelsetcols = transformColumnNameList(RelationGetRelid(rel),
 											  fkconstraint->fk_del_set_cols,
@@ -9922,19 +9936,41 @@ ATAddForeignKeyConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
 		numpks = transformFkeyGetPrimaryKey(pkrel, &indexOid,
 											&fkconstraint->pk_attrs,
 											pkattnum, pktypoid,
-											opclasses);
+											opclasses, &pk_has_without_overlaps);
+
+		/* If the primary key uses WITHOUT OVERLAPS, the fk must use PERIOD */
+		if (pk_has_without_overlaps && !fkconstraint->fk_with_period)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_FOREIGN_KEY),
+					errmsg("foreign key uses PERIOD on the referenced table but not the referencing table"));
 	}
 	else
 	{
 		numpks = transformColumnNameList(RelationGetRelid(pkrel),
 										 fkconstraint->pk_attrs,
 										 pkattnum, pktypoid);
+
+		/* Since we got pk_attrs, one should be a period. */
+		if (with_period && !fkconstraint->pk_with_period)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_FOREIGN_KEY),
+					errmsg("foreign key uses PERIOD on the referencing table but not the referenced table"));
+
 		/* Look for an index matching the column list */
 		indexOid = transformFkeyCheckAttrs(pkrel, numpks, pkattnum,
-										   opclasses);
+										   with_period, opclasses, &pk_has_without_overlaps);
 	}
 
 	/*
+	 * If the referenced primary key has WITHOUT OVERLAPS, the foreign key
+	 * must use PERIOD.
+	 */
+	if (pk_has_without_overlaps && !with_period)
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_FOREIGN_KEY),
+				errmsg("foreign key must use PERIOD when referencing a primary using WITHOUT OVERLAPS"));
+
+	/*
 	 * Now we can check permissions.
 	 */
 	checkFkeyPermissions(pkrel, pkattnum, numpks);
@@ -9968,6 +10004,28 @@ ATAddForeignKeyConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	}
 
 	/*
+	 * Some actions are currently unsupported for foreign keys using PERIOD.
+	 */
+	if (fkconstraint->fk_with_period)
+	{
+		if (fkconstraint->fk_upd_action == FKCONSTR_ACTION_CASCADE ||
+			fkconstraint->fk_upd_action == FKCONSTR_ACTION_SETNULL ||
+			fkconstraint->fk_upd_action == FKCONSTR_ACTION_SETDEFAULT)
+			ereport(ERROR,
+					errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("unsupported %s action for foreign key constraint using PERIOD",
+						   "ON UPDATE"));
+
+		if (fkconstraint->fk_del_action == FKCONSTR_ACTION_CASCADE ||
+			fkconstraint->fk_del_action == FKCONSTR_ACTION_SETNULL ||
+			fkconstraint->fk_del_action == FKCONSTR_ACTION_SETDEFAULT)
+			ereport(ERROR,
+					errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					errmsg("unsupported %s action for foreign key constraint using PERIOD",
+						   "ON DELETE"));
+	}
+
+	/*
 	 * Look up the equality operators to use in the constraint.
 	 *
 	 * Note that we have to be careful about the difference between the actual
@@ -10013,16 +10071,56 @@ ATAddForeignKeyConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
 		opcintype = cla_tup->opcintype;
 		ReleaseSysCache(cla_ht);
 
-		/*
-		 * Check it's a btree; currently this can never fail since no other
-		 * index AMs support unique indexes.  If we ever did have other types
-		 * of unique indexes, we'd need a way to determine which operator
-		 * strategy number is equality.  (Is it reasonable to insist that
-		 * every such index AM use btree's number for equality?)
-		 */
-		if (amid != BTREE_AM_OID)
-			elog(ERROR, "only b-tree indexes are supported for foreign keys");
-		eqstrategy = BTEqualStrategyNumber;
+		if (with_period)
+		{
+			StrategyNumber rtstrategy;
+			bool		for_overlaps = with_period && i == numpks - 1;
+
+			/*
+			 * GiST indexes are required to support temporal foreign keys
+			 * because they combine equals and overlaps.
+			 */
+			if (amid != GIST_AM_OID)
+				elog(ERROR, "only GiST indexes are supported for temporal foreign keys");
+
+			rtstrategy = for_overlaps ? RTOverlapStrategyNumber : RTEqualStrategyNumber;
+
+			/*
+			 * An opclass can use whatever strategy numbers it wants, so we
+			 * ask the opclass what number it actually uses instead of our RT*
+			 * constants.
+			 */
+			eqstrategy = GistTranslateStratnum(opclasses[i], rtstrategy);
+			if (eqstrategy == InvalidStrategy)
+			{
+				HeapTuple	tuple;
+
+				tuple = SearchSysCache1(CLAOID, ObjectIdGetDatum(opclasses[i]));
+				if (!HeapTupleIsValid(tuple))
+					elog(ERROR, "cache lookup failed for operator class %u", opclasses[i]);
+
+				ereport(ERROR,
+						errcode(ERRCODE_UNDEFINED_OBJECT),
+						for_overlaps
+						? errmsg("could not identify an overlaps operator for foreign key")
+						: errmsg("could not identify an equality operator for foreign key"),
+						errdetail("Could not translate strategy number %d for operator class \"%s\" for access method \"%s\".",
+								  rtstrategy, NameStr(((Form_pg_opclass) GETSTRUCT(tuple))->opcname), "gist"));
+			}
+		}
+		else
+		{
+			/*
+			 * Check it's a btree; currently this can never fail since no
+			 * other index AMs support unique indexes.  If we ever did have
+			 * other types of unique indexes, we'd need a way to determine
+			 * which operator strategy number is equality.  (We could use
+			 * something like GistTranslateStratnum.)
+			 */
+			if (amid != BTREE_AM_OID)
+				elog(ERROR, "only b-tree indexes are supported for foreign keys");
+			eqstrategy = BTEqualStrategyNumber;
+		}
 
 		/*
 		 * There had better be a primary equality operator for the index.
@@ -10173,6 +10271,22 @@ ATAddForeignKeyConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	}
 
 	/*
+	 * For FKs with PERIOD we need additional operators to check whether the
+	 * referencing row's range is contained by the aggregated ranges of the
+	 * referenced row(s). For rangetypes and multirangetypes this is
+	 * fk.periodatt <@ range_agg(pk.periodatt). Those are the only types we
+	 * support for now. FKs will look these up at "runtime", but we should
+	 * make sure the lookup works here, even if we don't use the values.
+	 */
+	if (with_period)
+	{
+		Oid			periodoperoid;
+		Oid			aggedperiodoperoid;
+
+		FindFKPeriodOpers(opclasses[numpks - 1], &periodoperoid, &aggedperiodoperoid);
+	}
+
+	/*
 	 * Create all the constraint and trigger objects, recursing to partitions
 	 * as necessary.  First handle the referenced side.
 	 */
@@ -10188,7 +10302,8 @@ ATAddForeignKeyConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
 									 numfkdelsetcols,
 									 fkdelsetcols,
 									 old_check_ok,
-									 InvalidOid, InvalidOid);
+									 InvalidOid, InvalidOid,
+									 with_period);
 
 	/* Now handle the referencing side. */
 	addFkRecurseReferencing(wqueue, fkconstraint, rel, pkrel,
@@ -10204,7 +10319,8 @@ ATAddForeignKeyConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
 							fkdelsetcols,
 							old_check_ok,
 							lockmode,
-							InvalidOid, InvalidOid);
+							InvalidOid, InvalidOid,
+							with_period);
 
 	/*
 	 * Done.  Close pk table, but keep lock until we've committed.
@@ -10289,7 +10405,8 @@ addFkRecurseReferenced(List **wqueue, Constraint *fkconstraint, Relation rel,
 					   Oid *ppeqoperators, Oid *ffeqoperators,
 					   int numfkdelsetcols, int16 *fkdelsetcols,
 					   bool old_check_ok,
-					   Oid parentDelTrigger, Oid parentUpdTrigger)
+					   Oid parentDelTrigger, Oid parentUpdTrigger,
+					   bool with_period)
 {
 	ObjectAddress address;
 	Oid			constrOid;
@@ -10375,7 +10492,7 @@ addFkRecurseReferenced(List **wqueue, Constraint *fkconstraint, Relation rel,
 									  conislocal,	/* islocal */
 									  coninhcount,	/* inhcount */
 									  connoinherit, /* conNoInherit */
-									  false,	/* conPeriod */
+									  with_period,	/* conPeriod */
 									  false);	/* is_internal */
 
 	ObjectAddressSet(address, ConstraintRelationId, constrOid);
@@ -10451,7 +10568,8 @@ addFkRecurseReferenced(List **wqueue, Constraint *fkconstraint, Relation rel,
 								   pfeqoperators, ppeqoperators, ffeqoperators,
 								   numfkdelsetcols, fkdelsetcols,
 								   old_check_ok,
-								   deleteTriggerOid, updateTriggerOid);
+								   deleteTriggerOid, updateTriggerOid,
+								   with_period);
 
 			/* Done -- clean up (but keep the lock) */
 			table_close(partRel, NoLock);
@@ -10509,7 +10627,8 @@ addFkRecurseReferencing(List **wqueue, Constraint *fkconstraint, Relation rel,
 						Oid *pfeqoperators, Oid *ppeqoperators, Oid *ffeqoperators,
 						int numfkdelsetcols, int16 *fkdelsetcols,
 						bool old_check_ok, LOCKMODE lockmode,
-						Oid parentInsTrigger, Oid parentUpdTrigger)
+						Oid parentInsTrigger, Oid parentUpdTrigger,
+						bool with_period)
 {
 	Oid			insertTriggerOid,
 				updateTriggerOid;
@@ -10557,6 +10676,7 @@ addFkRecurseReferencing(List **wqueue, Constraint *fkconstraint, Relation rel,
 			newcon->refrelid = RelationGetRelid(pkrel);
 			newcon->refindid = indexOid;
 			newcon->conid = parentConstr;
+			newcon->conwithperiod = fkconstraint->fk_with_period;
 			newcon->qual = (Node *) fkconstraint;
 
 			tab->constraints = lappend(tab->constraints, newcon);
@@ -10674,7 +10794,7 @@ addFkRecurseReferencing(List **wqueue, Constraint *fkconstraint, Relation rel,
 									  false,
 									  1,
 									  false,
-									  false,	/* conPeriod */
+									  with_period,	/* conPeriod */
 									  false);
 
 			/*
@@ -10705,7 +10825,8 @@ addFkRecurseReferencing(List **wqueue, Constraint *fkconstraint, Relation rel,
 									old_check_ok,
 									lockmode,
 									insertTriggerOid,
-									updateTriggerOid);
+									updateTriggerOid,
+									with_period);
 
 			table_close(partition, NoLock);
 		}
@@ -10941,7 +11062,8 @@ CloneFkReferenced(Relation parentRel, Relation partitionRel)
 							   confdelsetcols,
 							   true,
 							   deleteTriggerOid,
-							   updateTriggerOid);
+							   updateTriggerOid,
+							   constrForm->conperiod);
 
 		table_close(fkRel, NoLock);
 		ReleaseSysCache(tuple);
@@ -11034,6 +11156,7 @@ CloneFkReferencing(List **wqueue, Relation parentRel, Relation partRel)
 		ListCell   *lc;
 		Oid			insertTriggerOid,
 					updateTriggerOid;
+		bool		with_period;
 
 		tuple = SearchSysCache1(CONSTROID, ObjectIdGetDatum(parentConstrOid));
 		if (!HeapTupleIsValid(tuple))
@@ -11149,6 +11272,7 @@ CloneFkReferencing(List **wqueue, Relation parentRel, Relation partRel)
 			fkconstraint->conname = pstrdup(NameStr(constrForm->conname));
 
 		indexOid = constrForm->conindid;
+		with_period = constrForm->conperiod;
 		constrOid =
 			CreateConstraintEntry(fkconstraint->conname,
 								  constrForm->connamespace,
@@ -11180,7 +11304,7 @@ CloneFkReferencing(List **wqueue, Relation parentRel, Relation partRel)
 								  false,	/* islocal */
 								  1,	/* inhcount */
 								  false,	/* conNoInherit */
-								  false,	/* conPeriod */
+								  with_period,	/* conPeriod */
 								  true);
 
 		/* Set up partition dependencies for the new constraint */
@@ -11214,7 +11338,8 @@ CloneFkReferencing(List **wqueue, Relation parentRel, Relation partRel)
 								false,	/* no old check exists */
 								AccessExclusiveLock,
 								insertTriggerOid,
-								updateTriggerOid);
+								updateTriggerOid,
+								with_period);
 		table_close(pkrel, NoLock);
 	}
 
@@ -12024,7 +12149,8 @@ transformColumnNameList(Oid relId, List *colList,
  *
  *	Look up the names, attnums, and types of the primary key attributes
  *	for the pkrel.  Also return the index OID and index opclasses of the
- *	index supporting the primary key.
+ *	index supporting the primary key.  Also return whether the index has
+ *	WITHOUT OVERLAPS.
  *
  *	All parameters except pkrel are output parameters.  Also, the function
  *	return value is the number of attributes in the primary key.
@@ -12035,7 +12161,7 @@ static int
 transformFkeyGetPrimaryKey(Relation pkrel, Oid *indexOid,
 						   List **attnamelist,
 						   int16 *attnums, Oid *atttypids,
-						   Oid *opclasses)
+						   Oid *opclasses, bool *pk_has_without_overlaps)
 {
 	List	   *indexoidlist;
 	ListCell   *indexoidscan;
@@ -12113,6 +12239,8 @@ transformFkeyGetPrimaryKey(Relation pkrel, Oid *indexOid,
 							   makeString(pstrdup(NameStr(*attnumAttName(pkrel, pkattno)))));
 	}
 
+	*pk_has_without_overlaps = indexStruct->indisexclusion;
+
 	ReleaseSysCache(indexTuple);
 
 	return i;
@@ -12126,14 +12254,16 @@ transformFkeyGetPrimaryKey(Relation pkrel, Oid *indexOid,
  *
  *	Returns the OID of the unique index supporting the constraint and
  *	populates the caller-provided 'opclasses' array with the opclasses
- *	associated with the index columns.
+ *	associated with the index columns.  Also sets whether the index
+ *	uses WITHOUT OVERLAPS.
  *
  *	Raises an ERROR on validation failure.
  */
 static Oid
 transformFkeyCheckAttrs(Relation pkrel,
 						int numattrs, int16 *attnums,
-						Oid *opclasses)
+						bool with_period, Oid *opclasses,
+						bool *pk_has_without_overlaps)
 {
 	Oid			indexoid = InvalidOid;
 	bool		found = false;
@@ -12180,12 +12310,12 @@ transformFkeyCheckAttrs(Relation pkrel,
 		indexStruct = (Form_pg_index) GETSTRUCT(indexTuple);
 
 		/*
-		 * Must have the right number of columns; must be unique and not a
-		 * partial index; forget it if there are any expressions, too. Invalid
-		 * indexes are out as well.
+		 * Must have the right number of columns; must be unique (or if
+		 * temporal then exclusion instead) and not a partial index; forget it
+		 * if there are any expressions, too. Invalid indexes are out as well.
 		 */
 		if (indexStruct->indnkeyatts == numattrs &&
-			indexStruct->indisunique &&
+			(with_period ? indexStruct->indisexclusion : indexStruct->indisunique) &&
 			indexStruct->indisvalid &&
 			heap_attisnull(indexTuple, Anum_pg_index_indpred, NULL) &&
 			heap_attisnull(indexTuple, Anum_pg_index_indexprs, NULL))
@@ -12223,6 +12353,13 @@ transformFkeyCheckAttrs(Relation pkrel,
 				if (!found)
 					break;
 			}
+			/* The last attribute in the index must be the PERIOD FK part */
+			if (found && with_period)
+			{
+				int16		periodattnum = attnums[numattrs - 1];
+
+				found = (periodattnum == indexStruct->indkey.values[numattrs - 1]);
+			}
 
 			/*
 			 * Refuse to use a deferrable unique/primary key.  This is per SQL
@@ -12238,6 +12375,10 @@ transformFkeyCheckAttrs(Relation pkrel,
 				found_deferrable = true;
 				found = false;
 			}
+
+			/* We need to know whether the index has WITHOUT OVERLAPS */
+			if (found)
+				*pk_has_without_overlaps = indexStruct->indisexclusion;
 		}
 		ReleaseSysCache(indexTuple);
 		if (found)
@@ -12332,7 +12473,8 @@ validateForeignKeyConstraint(char *conname,
 							 Relation rel,
 							 Relation pkrel,
 							 Oid pkindOid,
-							 Oid constraintOid)
+							 Oid constraintOid,
+							 bool hasperiod)
 {
 	TupleTableSlot *slot;
 	TableScanDesc scan;
@@ -12360,9 +12502,11 @@ validateForeignKeyConstraint(char *conname,
 
 	/*
 	 * See if we can do it with a single LEFT JOIN query.  A false result
-	 * indicates we must proceed with the fire-the-trigger method.
+	 * indicates we must proceed with the fire-the-trigger method. We can't do
+	 * a LEFT JOIN for temporal FKs yet, but we can once we support temporal
+	 * left joins.
 	 */
-	if (RI_Initial_Check(&trig, rel, pkrel))
+	if (!hasperiod && RI_Initial_Check(&trig, rel, pkrel))
 		return;
 
 	/*
@@ -12513,6 +12657,7 @@ createForeignKeyActionTriggers(Relation rel, Oid refRelOid, Constraint *fkconstr
 	fk_trigger->whenClause = NULL;
 	fk_trigger->transitionRels = NIL;
 	fk_trigger->constrrel = NULL;
+
 	switch (fkconstraint->fk_del_action)
 	{
 		case FKCONSTR_ACTION_NOACTION:
@@ -12573,6 +12718,7 @@ createForeignKeyActionTriggers(Relation rel, Oid refRelOid, Constraint *fkconstr
 	fk_trigger->whenClause = NULL;
 	fk_trigger->transitionRels = NIL;
 	fk_trigger->constrrel = NULL;
+
 	switch (fkconstraint->fk_upd_action)
 	{
 		case FKCONSTR_ACTION_NOACTION: