Avoid bogus scans of partitions when validating FKs to partitioned tables

Validating an unvalidated foreign key that references a partitioned
table would try to queue validations for each individual partition of
the referenced table, but this is wrong: each individual partition would
not necessarily have all the referenced rows, so errors would be raised.
Avoid doing that.  The pg_constraint rows that cause this to happen are
only there to support the action triggers that implement the DELETE/
UPDATE actions of the FK, so no validating scan is necessary.

This was an oversight in commit b663b9436e.

An equivalent oversight exists for NOT ENFORCED constraints, which is
not fixed in this commit.

Author: Amul Sul <sulamul@gmail.com>
Reported-by: Antonin Houska <ah@cybertec.at>
Reviewed-by: jian he <jian.universality@gmail.com>
Reviewed-by: Tender Wang <tndrwang@gmail.com>
Discussion: https://postgr.es/m/26983.1748418675@localhost

src/test/regress/expected/foreign_key.out

@@ -1895,29 +1895,67 @@ WHERE conrelid::regclass::text like 'fk_partitioned_fk%' ORDER BY oid::regclass:
 (5 rows)
 
 DROP TABLE fk_partitioned_fk, fk_notpartitioned_pk;
--- NOT VALID foreign key on a non-partitioned table referencing a partitioned table
+-- NOT VALID foreign key on a non-partitioned table referencing a partitioned
+-- table
 CREATE TABLE fk_partitioned_pk (a int, b int, PRIMARY KEY (a, b)) PARTITION BY RANGE (a, b);
 CREATE TABLE fk_partitioned_pk_1 PARTITION OF fk_partitioned_pk FOR VALUES FROM (0,0) TO (1000,1000);
+CREATE TABLE fk_partitioned_pk_2 PARTITION OF fk_partitioned_pk FOR VALUES FROM (1000,1000) TO (2000,2000);
 CREATE TABLE fk_notpartitioned_fk (b int, a int);
-ALTER TABLE fk_notpartitioned_fk ADD FOREIGN KEY (a, b) REFERENCES fk_partitioned_pk NOT VALID;
--- Constraint will be invalid.
-SELECT conname, convalidated FROM pg_constraint
+INSERT INTO fk_partitioned_pk VALUES(100,100), (1000,1000);
+INSERT INTO fk_notpartitioned_fk VALUES(100,100), (1000,1000);
+ALTER TABLE fk_notpartitioned_fk ADD CONSTRAINT fk_notpartitioned_fk_a_b_fkey
+	FOREIGN KEY (a, b) REFERENCES fk_partitioned_pk NOT VALID;
+-- All constraints will be invalid.
+SELECT conname, conenforced, convalidated FROM pg_constraint
 WHERE conrelid = 'fk_notpartitioned_fk'::regclass ORDER BY oid::regclass::text;
-             conname             | convalidated 
----------------------------------+--------------
- fk_notpartitioned_fk_a_b_fkey   | f
- fk_notpartitioned_fk_a_b_fkey_1 | f
-(2 rows)
+             conname             | conenforced | convalidated 
+---------------------------------+-------------+--------------
+ fk_notpartitioned_fk_a_b_fkey   | t           | f
+ fk_notpartitioned_fk_a_b_fkey_1 | t           | f
+ fk_notpartitioned_fk_a_b_fkey_2 | t           | f
+(3 rows)
 
 ALTER TABLE fk_notpartitioned_fk VALIDATE CONSTRAINT fk_notpartitioned_fk_a_b_fkey;
 -- All constraints are now valid.
-SELECT conname, convalidated FROM pg_constraint
+SELECT conname, conenforced, convalidated FROM pg_constraint
 WHERE conrelid = 'fk_notpartitioned_fk'::regclass ORDER BY oid::regclass::text;
-             conname             | convalidated 
----------------------------------+--------------
- fk_notpartitioned_fk_a_b_fkey   | t
- fk_notpartitioned_fk_a_b_fkey_1 | t
-(2 rows)
+             conname             | conenforced | convalidated 
+---------------------------------+-------------+--------------
+ fk_notpartitioned_fk_a_b_fkey   | t           | t
+ fk_notpartitioned_fk_a_b_fkey_1 | t           | t
+ fk_notpartitioned_fk_a_b_fkey_2 | t           | t
+(3 rows)
+
+-- test a self-referential FK
+ALTER TABLE fk_partitioned_pk ADD CONSTRAINT selffk FOREIGN KEY (a, b) REFERENCES fk_partitioned_pk NOT VALID;
+CREATE TABLE fk_partitioned_pk_3 PARTITION OF fk_partitioned_pk FOR VALUES FROM (2000,2000) TO (3000,3000)
+  PARTITION BY RANGE (a);
+CREATE TABLE fk_partitioned_pk_3_1 PARTITION OF fk_partitioned_pk_3 FOR VALUES FROM (2000) TO (2100);
+SELECT conname, conenforced, convalidated FROM pg_constraint
+WHERE conrelid = 'fk_partitioned_pk'::regclass AND contype = 'f'
+ORDER BY oid::regclass::text;
+  conname   | conenforced | convalidated 
+------------+-------------+--------------
+ selffk     | t           | f
+ selffk_1   | t           | f
+ selffk_2   | t           | f
+ selffk_3   | t           | f
+ selffk_3_1 | t           | f
+(5 rows)
+
+ALTER TABLE fk_partitioned_pk_2 VALIDATE CONSTRAINT selffk;
+ALTER TABLE fk_partitioned_pk VALIDATE CONSTRAINT selffk;
+SELECT conname, conenforced, convalidated FROM pg_constraint
+WHERE conrelid = 'fk_partitioned_pk'::regclass AND contype = 'f'
+ORDER BY oid::regclass::text;
+  conname   | conenforced | convalidated 
+------------+-------------+--------------
+ selffk     | t           | t
+ selffk_1   | t           | t
+ selffk_2   | t           | t
+ selffk_3   | t           | t
+ selffk_3_1 | t           | t
+(5 rows)
 
 DROP TABLE fk_notpartitioned_fk, fk_partitioned_pk;
 -- Test some other exotic foreign key features: MATCH SIMPLE, ON UPDATE/DELETE

src/test/regress/sql/foreign_key.sql

@@ -1389,22 +1389,41 @@ WHERE conrelid::regclass::text like 'fk_partitioned_fk%' ORDER BY oid::regclass:
 
 DROP TABLE fk_partitioned_fk, fk_notpartitioned_pk;
 
--- NOT VALID foreign key on a non-partitioned table referencing a partitioned table
+-- NOT VALID foreign key on a non-partitioned table referencing a partitioned
+-- table
 CREATE TABLE fk_partitioned_pk (a int, b int, PRIMARY KEY (a, b)) PARTITION BY RANGE (a, b);
 CREATE TABLE fk_partitioned_pk_1 PARTITION OF fk_partitioned_pk FOR VALUES FROM (0,0) TO (1000,1000);
+CREATE TABLE fk_partitioned_pk_2 PARTITION OF fk_partitioned_pk FOR VALUES FROM (1000,1000) TO (2000,2000);
 CREATE TABLE fk_notpartitioned_fk (b int, a int);
-ALTER TABLE fk_notpartitioned_fk ADD FOREIGN KEY (a, b) REFERENCES fk_partitioned_pk NOT VALID;
+INSERT INTO fk_partitioned_pk VALUES(100,100), (1000,1000);
+INSERT INTO fk_notpartitioned_fk VALUES(100,100), (1000,1000);
+ALTER TABLE fk_notpartitioned_fk ADD CONSTRAINT fk_notpartitioned_fk_a_b_fkey
+	FOREIGN KEY (a, b) REFERENCES fk_partitioned_pk NOT VALID;
 
--- Constraint will be invalid.
-SELECT conname, convalidated FROM pg_constraint
+-- All constraints will be invalid.
+SELECT conname, conenforced, convalidated FROM pg_constraint
 WHERE conrelid = 'fk_notpartitioned_fk'::regclass ORDER BY oid::regclass::text;
 
 ALTER TABLE fk_notpartitioned_fk VALIDATE CONSTRAINT fk_notpartitioned_fk_a_b_fkey;
 
 -- All constraints are now valid.
-SELECT conname, convalidated FROM pg_constraint
+SELECT conname, conenforced, convalidated FROM pg_constraint
 WHERE conrelid = 'fk_notpartitioned_fk'::regclass ORDER BY oid::regclass::text;
 
+-- test a self-referential FK
+ALTER TABLE fk_partitioned_pk ADD CONSTRAINT selffk FOREIGN KEY (a, b) REFERENCES fk_partitioned_pk NOT VALID;
+CREATE TABLE fk_partitioned_pk_3 PARTITION OF fk_partitioned_pk FOR VALUES FROM (2000,2000) TO (3000,3000)
+  PARTITION BY RANGE (a);
+CREATE TABLE fk_partitioned_pk_3_1 PARTITION OF fk_partitioned_pk_3 FOR VALUES FROM (2000) TO (2100);
+SELECT conname, conenforced, convalidated FROM pg_constraint
+WHERE conrelid = 'fk_partitioned_pk'::regclass AND contype = 'f'
+ORDER BY oid::regclass::text;
+ALTER TABLE fk_partitioned_pk_2 VALIDATE CONSTRAINT selffk;
+ALTER TABLE fk_partitioned_pk VALIDATE CONSTRAINT selffk;
+SELECT conname, conenforced, convalidated FROM pg_constraint
+WHERE conrelid = 'fk_partitioned_pk'::regclass AND contype = 'f'
+ORDER BY oid::regclass::text;
+
 DROP TABLE fk_notpartitioned_fk, fk_partitioned_pk;
 
 -- Test some other exotic foreign key features: MATCH SIMPLE, ON UPDATE/DELETE