Increase test coverage in RI_FKey_fk_upd_check_required()

This checks the code path of FKCONSTR_MATCH_FULL and
RI_KEYS_SOME_NULL.
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

@@ -143,6 +143,12 @@ SELECT * FROM FKTABLE;
         |        |      8
 (5 rows)
 
+-- Check update with part of key null
+UPDATE FKTABLE SET ftest1 = NULL WHERE ftest1 = 1;
+ERROR:  insert or update on table "fktable" violates foreign key constraint "constrname"
+DETAIL:  MATCH FULL does not allow mixing of null and nonnull key values.
+-- Check update with old and new key values equal
+UPDATE FKTABLE SET ftest1 = 1 WHERE ftest1 = 1;
 -- Try altering the column type where foreign keys are involved
 ALTER TABLE PKTABLE ALTER COLUMN ptest1 TYPE bigint;
 ALTER TABLE FKTABLE ALTER COLUMN ftest1 TYPE bigint;
@@ -158,11 +164,11 @@ SELECT * FROM PKTABLE;
 SELECT * FROM FKTABLE;
  ftest1 | ftest2 | ftest3 
 --------+--------+--------
-      1 |      3 |      5
       3 |      6 |     12
         |        |      0
         |        |      4
         |        |      8
+      1 |      3 |      5
 (5 rows)
 
 DROP TABLE PKTABLE CASCADE;
@@ -1597,6 +1603,15 @@ INSERT INTO fk_notpartitioned_pk VALUES (2502, 2503);
 INSERT INTO fk_partitioned_fk_3 (a, b) VALUES (2502, 2503);
 -- this always works
 INSERT INTO fk_partitioned_fk (a,b) VALUES (NULL, NULL);
+-- MATCH FULL
+INSERT INTO fk_notpartitioned_pk VALUES (1, 2);
+CREATE TABLE fk_partitioned_fk_full (x int, y int) PARTITION BY RANGE (x);
+CREATE TABLE fk_partitioned_fk_full_1 PARTITION OF fk_partitioned_fk_full DEFAULT;
+ALTER TABLE fk_partitioned_fk_full ADD FOREIGN KEY (x, y) REFERENCES fk_notpartitioned_pk MATCH FULL;
+INSERT INTO fk_partitioned_fk_full VALUES (1, NULL);  -- fails
+ERROR:  insert or update on table "fk_partitioned_fk_full_1" violates foreign key constraint "fk_partitioned_fk_full_x_fkey"
+DETAIL:  MATCH FULL does not allow mixing of null and nonnull key values.
+DROP TABLE fk_partitioned_fk_full;
 -- ON UPDATE SET NULL
 SELECT tableoid::regclass, a, b FROM fk_partitioned_fk WHERE b IS NULL ORDER BY a;
       tableoid       |  a   | b 

src/test/regress/sql/foreign_key.sql

@@ -97,6 +97,12 @@ UPDATE PKTABLE SET ptest1=1 WHERE ptest1=2;
 -- Check FKTABLE for update of matched row
 SELECT * FROM FKTABLE;
 
+-- Check update with part of key null
+UPDATE FKTABLE SET ftest1 = NULL WHERE ftest1 = 1;
+
+-- Check update with old and new key values equal
+UPDATE FKTABLE SET ftest1 = 1 WHERE ftest1 = 1;
+
 -- Try altering the column type where foreign keys are involved
 ALTER TABLE PKTABLE ALTER COLUMN ptest1 TYPE bigint;
 ALTER TABLE FKTABLE ALTER COLUMN ftest1 TYPE bigint;
@@ -1204,6 +1210,14 @@ INSERT INTO fk_partitioned_fk_3 (a, b) VALUES (2502, 2503);
 -- this always works
 INSERT INTO fk_partitioned_fk (a,b) VALUES (NULL, NULL);
 
+-- MATCH FULL
+INSERT INTO fk_notpartitioned_pk VALUES (1, 2);
+CREATE TABLE fk_partitioned_fk_full (x int, y int) PARTITION BY RANGE (x);
+CREATE TABLE fk_partitioned_fk_full_1 PARTITION OF fk_partitioned_fk_full DEFAULT;
+ALTER TABLE fk_partitioned_fk_full ADD FOREIGN KEY (x, y) REFERENCES fk_notpartitioned_pk MATCH FULL;
+INSERT INTO fk_partitioned_fk_full VALUES (1, NULL);  -- fails
+DROP TABLE fk_partitioned_fk_full;
+
 -- ON UPDATE SET NULL
 SELECT tableoid::regclass, a, b FROM fk_partitioned_fk WHERE b IS NULL ORDER BY a;
 UPDATE fk_notpartitioned_pk SET a = a + 1 WHERE a = 2502;