diff --git a/src/backend/catalog/pg_constraint.c b/src/backend/catalog/pg_constraint.c
index 4002317f705..59565b9d881 100644
--- a/src/backend/catalog/pg_constraint.c
+++ b/src/backend/catalog/pg_constraint.c
@@ -120,8 +120,9 @@ CreateConstraintEntry(const char *constraintName,
 	if (foreignNKeys > 0)
 	{
 		Datum	   *fkdatums;
+		int			nkeys = Max(foreignNKeys, numFkDeleteSetCols);
 
-		fkdatums = (Datum *) palloc(foreignNKeys * sizeof(Datum));
+		fkdatums = (Datum *) palloc(nkeys * sizeof(Datum));
 		for (i = 0; i < foreignNKeys; i++)
 			fkdatums[i] = Int16GetDatum(foreignKey[i]);
 		confkeyArray = construct_array_builtin(fkdatums, foreignNKeys, INT2OID);
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 40fe7685239..b4c0a615873 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -498,8 +498,8 @@ static ObjectAddress ATAddForeignKeyConstraint(List **wqueue, AlteredTableInfo *
 											   Relation rel, Constraint *fkconstraint,
 											   bool recurse, bool recursing,
 											   LOCKMODE lockmode);
-static void validateFkOnDeleteSetColumns(int numfks, const int16 *fkattnums,
-										 int numfksetcols, const int16 *fksetcolsattnums,
+static int	validateFkOnDeleteSetColumns(int numfks, const int16 *fkattnums,
+										 int numfksetcols, int16 *fksetcolsattnums,
 										 List *fksetcols);
 static ObjectAddress addFkConstraint(addFkConstraintSides fkside,
 									 char *constraintname,
@@ -9340,9 +9340,10 @@ ATAddForeignKeyConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	numfkdelsetcols = transformColumnNameList(RelationGetRelid(rel),
 											  fkconstraint->fk_del_set_cols,
 											  fkdelsetcols, NULL);
-	validateFkOnDeleteSetColumns(numfks, fkattnum,
-								 numfkdelsetcols, fkdelsetcols,
-								 fkconstraint->fk_del_set_cols);
+	numfkdelsetcols = validateFkOnDeleteSetColumns(numfks, fkattnum,
+												   numfkdelsetcols,
+												   fkdelsetcols,
+												   fkconstraint->fk_del_set_cols);
 
 	/*
 	 * If the attribute list for the referenced table was omitted, lookup the
@@ -9663,17 +9664,23 @@ ATAddForeignKeyConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
  * validateFkOnDeleteSetColumns
  *		Verifies that columns used in ON DELETE SET NULL/DEFAULT (...)
  *		column lists are valid.
+ *
+ * If there are duplicates in the fksetcolsattnums[] array, this silently
+ * removes the dups.  The new count of numfksetcols is returned.
  */
-void
+static int
 validateFkOnDeleteSetColumns(int numfks, const int16 *fkattnums,
-							 int numfksetcols, const int16 *fksetcolsattnums,
+							 int numfksetcols, int16 *fksetcolsattnums,
 							 List *fksetcols)
 {
+	int			numcolsout = 0;
+
 	for (int i = 0; i < numfksetcols; i++)
 	{
 		int16		setcol_attnum = fksetcolsattnums[i];
 		bool		seen = false;
 
+		/* Make sure it's in fkattnums[] */
 		for (int j = 0; j < numfks; j++)
 		{
 			if (fkattnums[j] == setcol_attnum)
@@ -9691,7 +9698,21 @@ validateFkOnDeleteSetColumns(int numfks, const int16 *fkattnums,
 					(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
 					 errmsg("column \"%s\" referenced in ON DELETE SET action must be part of foreign key", col)));
 		}
+
+		/* Now check for dups */
+		seen = false;
+		for (int j = 0; j < numcolsout; j++)
+		{
+			if (fksetcolsattnums[j] == setcol_attnum)
+			{
+				seen = true;
+				break;
+			}
+		}
+		if (!seen)
+			fksetcolsattnums[numcolsout++] = setcol_attnum;
 	}
+	return numcolsout;
 }
 
 /*
diff --git a/src/test/regress/expected/foreign_key.out b/src/test/regress/expected/foreign_key.out
index 9f3cd3e1d32..19398fe2b4a 100644
--- a/src/test/regress/expected/foreign_key.out
+++ b/src/test/regress/expected/foreign_key.out
@@ -772,7 +772,8 @@ CREATE TABLE FKTABLE (
   fk_id_del_set_null int,
   fk_id_del_set_default int DEFAULT 0,
   FOREIGN KEY (tid, fk_id_del_set_null) REFERENCES PKTABLE ON DELETE SET NULL (fk_id_del_set_null),
-  FOREIGN KEY (tid, fk_id_del_set_default) REFERENCES PKTABLE ON DELETE SET DEFAULT (fk_id_del_set_default)
+  -- this tests handling of duplicate entries in SET DEFAULT column list
+  FOREIGN KEY (tid, fk_id_del_set_default) REFERENCES PKTABLE ON DELETE SET DEFAULT (fk_id_del_set_default, fk_id_del_set_default)
 );
 SELECT pg_get_constraintdef(oid) FROM pg_constraint WHERE conrelid = 'fktable'::regclass::oid ORDER BY oid;
                                                 pg_get_constraintdef                                                
diff --git a/src/test/regress/sql/foreign_key.sql b/src/test/regress/sql/foreign_key.sql
index 3078f7d45c2..1b0c04aa8fe 100644
--- a/src/test/regress/sql/foreign_key.sql
+++ b/src/test/regress/sql/foreign_key.sql
@@ -473,7 +473,8 @@ CREATE TABLE FKTABLE (
   fk_id_del_set_null int,
   fk_id_del_set_default int DEFAULT 0,
   FOREIGN KEY (tid, fk_id_del_set_null) REFERENCES PKTABLE ON DELETE SET NULL (fk_id_del_set_null),
-  FOREIGN KEY (tid, fk_id_del_set_default) REFERENCES PKTABLE ON DELETE SET DEFAULT (fk_id_del_set_default)
+  -- this tests handling of duplicate entries in SET DEFAULT column list
+  FOREIGN KEY (tid, fk_id_del_set_default) REFERENCES PKTABLE ON DELETE SET DEFAULT (fk_id_del_set_default, fk_id_del_set_default)
 );
 
 SELECT pg_get_constraintdef(oid) FROM pg_constraint WHERE conrelid = 'fktable'::regclass::oid ORDER BY oid;