Increase test coverage in RI_FKey_pk_upd_check_required()

This checks the case where the primary key has at least one null
column.

Reviewed-by: Alvaro Herrera <alvherre@2ndquadrant.com>
Reviewed-by: Mi Tar <mmitar@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/7ae17c95-0c99-d420-032a-c271f510112b@2ndquadrant.com/

src/test/regress/expected/foreign_key.out

@@ -397,6 +397,30 @@ SELECT * from FKTABLE;
         |      3 |      4 |      5
 (5 rows)
 
+DROP TABLE FKTABLE;
+DROP TABLE PKTABLE;
+-- restrict with null values
+CREATE TABLE PKTABLE ( ptest1 int, ptest2 int, ptest3 int, ptest4 text, UNIQUE(ptest1, ptest2, ptest3) );
+CREATE TABLE FKTABLE ( ftest1 int, ftest2 int, ftest3 int, ftest4 int,  CONSTRAINT constrname3
+			FOREIGN KEY(ftest1, ftest2, ftest3) REFERENCES PKTABLE (ptest1, ptest2, ptest3));
+INSERT INTO PKTABLE VALUES (1, 2, 3, 'test1');
+INSERT INTO PKTABLE VALUES (1, 3, NULL, 'test2');
+INSERT INTO PKTABLE VALUES (2, NULL, 4, 'test3');
+INSERT INTO FKTABLE VALUES (1, 2, 3, 1);
+DELETE FROM PKTABLE WHERE ptest1 = 2;
+SELECT * FROM PKTABLE;
+ ptest1 | ptest2 | ptest3 | ptest4 
+--------+--------+--------+--------
+      1 |      2 |      3 | test1
+      1 |      3 |        | test2
+(2 rows)
+
+SELECT * FROM FKTABLE;
+ ftest1 | ftest2 | ftest3 | ftest4 
+--------+--------+--------+--------
+      1 |      2 |      3 |      1
+(1 row)
+
 DROP TABLE FKTABLE;
 DROP TABLE PKTABLE;
 -- cascade update/delete

src/test/regress/sql/foreign_key.sql

@@ -260,6 +260,25 @@ SELECT * from FKTABLE;
 DROP TABLE FKTABLE;
 DROP TABLE PKTABLE;
 
+-- restrict with null values
+CREATE TABLE PKTABLE ( ptest1 int, ptest2 int, ptest3 int, ptest4 text, UNIQUE(ptest1, ptest2, ptest3) );
+CREATE TABLE FKTABLE ( ftest1 int, ftest2 int, ftest3 int, ftest4 int,  CONSTRAINT constrname3
+			FOREIGN KEY(ftest1, ftest2, ftest3) REFERENCES PKTABLE (ptest1, ptest2, ptest3));
+
+INSERT INTO PKTABLE VALUES (1, 2, 3, 'test1');
+INSERT INTO PKTABLE VALUES (1, 3, NULL, 'test2');
+INSERT INTO PKTABLE VALUES (2, NULL, 4, 'test3');
+
+INSERT INTO FKTABLE VALUES (1, 2, 3, 1);
+
+DELETE FROM PKTABLE WHERE ptest1 = 2;
+
+SELECT * FROM PKTABLE;
+SELECT * FROM FKTABLE;
+
+DROP TABLE FKTABLE;
+DROP TABLE PKTABLE;
+
 -- cascade update/delete
 CREATE TABLE PKTABLE ( ptest1 int, ptest2 int, ptest3 int, ptest4 text, PRIMARY KEY(ptest1, ptest2, ptest3) );
 CREATE TABLE FKTABLE ( ftest1 int, ftest2 int, ftest3 int, ftest4 int,  CONSTRAINT constrname3