Handle self-referencing FKs correctly in partitioned tables

For self-referencing foreign keys in partitioned tables, we weren't
handling creation of pg_constraint rows during CREATE TABLE PARTITION AS
as well as ALTER TABLE ATTACH PARTITION.  This is an old bug -- mostly,
we broke this in 614a406b4ff1 while trying to fix it (so 12.13, 13.9,
14.6 and 15.0 and up all behave incorrectly).  This commit reverts part
of that with additional fixes for full correctness, and installs more
tests to verify the parts we broke, not just the catalog contents but
also the user-visible behavior.

Backpatch to all live branches.  In branches 13 and 14, commit
46a8c27a7226 changed the behavior during DETACH to drop a FK
constraint rather than trying to repair it, because the complete fix of
repairing catalog constraints was problematic due to lack of previous
fixes.  For this reason, the test behavior in those branches is a bit
different.  However, as best as I can tell, the fix works correctly
there.

In release notes we have to recommend that all self-referencing foreign
keys on partitioned tables be recreated if partitions have been created
or attached after the FK was created, keeping in mind that violating
rows might already be present on the referencing side.

Reported-by: Guillaume Lelarge <guillaume@lelarge.info>
Reported-by: Matthew Gabeler-Lee <fastcat@gmail.com>
Reported-by: Luca Vallisa <luca.vallisa@gmail.com>
Discussion: https://postgr.es/m/CAECtzeWHCA+6tTcm2Oh2+g7fURUJpLZb-=pRXgeWJ-Pi+VU=_w@mail.gmail.com
Discussion: https://postgr.es/m/18156-a44bc7096f0683e6@postgresql.org
Discussion: https://postgr.es/m/CAAT=myvsiF-Attja5DcWoUWh21R12R-sfXECY2-3ynt8kaOqjw@mail.gmail.com

4 files changed, 126 insertions, 69 deletions

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 6cbc0b196d6..53dc3296c81 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -9577,14 +9577,14 @@ CloneForeignKeyConstraints(List **wqueue, Relation parentRel,
 	Assert(parentRel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE);
 
 	/*
-	 * Clone constraints for which the parent is on the referenced side.
+	 * First, clone constraints where the parent is on the referencing side.
 	 */
-	CloneFkReferenced(parentRel, partitionRel);
+	CloneFkReferencing(wqueue, parentRel, partitionRel);
 
 	/*
-	 * Now clone constraints where the parent is on the referencing side.
+	 * Clone constraints for which the parent is on the referenced side.
 	 */
-	CloneFkReferencing(wqueue, parentRel, partitionRel);
+	CloneFkReferenced(parentRel, partitionRel);
 }
 
 /*
@@ -9595,8 +9595,6 @@ CloneForeignKeyConstraints(List **wqueue, Relation parentRel,
  * clone those constraints to the given partition.  This is to be called
  * when the partition is being created or attached.
  *
- * This ignores self-referencing FKs; those are handled by CloneFkReferencing.
- *
  * This recurses to partitions, if the relation being attached is partitioned.
  * Recursion is done by calling addFkRecurseReferenced.
  */
@@ -9673,17 +9671,6 @@ CloneFkReferenced(Relation parentRel, Relation partitionRel)
 		}
 
 		/*
-		 * Don't clone self-referencing foreign keys, which can be in the
-		 * partitioned table or in the partition-to-be.
-		 */
-		if (constrForm->conrelid == RelationGetRelid(parentRel) ||
-			constrForm->conrelid == RelationGetRelid(partitionRel))
-		{
-			ReleaseSysCache(tuple);
-			continue;
-		}
-
-		/*
 		 * Because we're only expanding the key space at the referenced side,
 		 * we don't need to prevent any operation in the referencing table, so
 		 * AccessShareLock suffices (assumes that dropping the constraint
diff --git a/src/test/regress/expected/foreign_key.out b/src/test/regress/expected/foreign_key.out
index 496361392e9..2deb0fb68b0 100644
--- a/src/test/regress/expected/foreign_key.out
+++ b/src/test/regress/expected/foreign_key.out
@@ -1970,58 +1970,98 @@ CREATE TABLE part33_self_fk (
 	id_abc bigint
 );
 ALTER TABLE part3_self_fk ATTACH PARTITION part33_self_fk FOR VALUES FROM (30) TO (40);
-SELECT cr.relname, co.conname, co.contype, co.convalidated,
+-- verify that this constraint works
+INSERT INTO parted_self_fk VALUES (1, NULL), (2, NULL), (3, NULL);
+INSERT INTO parted_self_fk VALUES (10, 1), (11, 2), (12, 3) RETURNING tableoid::regclass;
+   tableoid    
+---------------
+ part2_self_fk
+ part2_self_fk
+ part2_self_fk
+(3 rows)
+
+INSERT INTO parted_self_fk VALUES (4, 5);	-- error: referenced doesn't exist
+ERROR:  insert or update on table "part1_self_fk" violates foreign key constraint "parted_self_fk_id_abc_fkey"
+DETAIL:  Key (id_abc)=(5) is not present in table "parted_self_fk".
+DELETE FROM parted_self_fk WHERE id = 1 RETURNING *;	-- error: reference remains
+ERROR:  update or delete on table "part1_self_fk" violates foreign key constraint "parted_self_fk_id_abc_fkey1" on table "parted_self_fk"
+DETAIL:  Key (id)=(1) is still referenced from table "parted_self_fk".
+SELECT cr.relname, co.conname, co.convalidated,
        p.conname AS conparent, p.convalidated, cf.relname AS foreignrel
 FROM pg_constraint co
 JOIN pg_class cr ON cr.oid = co.conrelid
 LEFT JOIN pg_class cf ON cf.oid = co.confrelid
 LEFT JOIN pg_constraint p ON p.oid = co.conparentid
-WHERE cr.oid IN (SELECT relid FROM pg_partition_tree('parted_self_fk'))
-ORDER BY co.contype, cr.relname, co.conname, p.conname;
-    relname     |          conname           | contype | convalidated |         conparent          | convalidated |   foreignrel   
-----------------+----------------------------+---------+--------------+----------------------------+--------------+----------------
- part1_self_fk  | parted_self_fk_id_abc_fkey | f       | t            | parted_self_fk_id_abc_fkey | t            | parted_self_fk
- part2_self_fk  | parted_self_fk_id_abc_fkey | f       | t            | parted_self_fk_id_abc_fkey | t            | parted_self_fk
- part32_self_fk | parted_self_fk_id_abc_fkey | f       | t            | parted_self_fk_id_abc_fkey | t            | parted_self_fk
- part33_self_fk | parted_self_fk_id_abc_fkey | f       | t            | parted_self_fk_id_abc_fkey | t            | parted_self_fk
- part3_self_fk  | parted_self_fk_id_abc_fkey | f       | t            | parted_self_fk_id_abc_fkey | t            | parted_self_fk
- parted_self_fk | parted_self_fk_id_abc_fkey | f       | t            |                            |              | parted_self_fk
- part1_self_fk  | part1_self_fk_pkey         | p       | t            | parted_self_fk_pkey        | t            | 
- part2_self_fk  | part2_self_fk_pkey         | p       | t            | parted_self_fk_pkey        | t            | 
- part32_self_fk | part32_self_fk_pkey        | p       | t            | part3_self_fk_pkey         | t            | 
- part33_self_fk | part33_self_fk_pkey        | p       | t            | part3_self_fk_pkey         | t            | 
- part3_self_fk  | part3_self_fk_pkey         | p       | t            | parted_self_fk_pkey        | t            | 
- parted_self_fk | parted_self_fk_pkey        | p       | t            |                            |              | 
-(12 rows)
+WHERE co.contype = 'f' AND
+      cr.oid IN (SELECT relid FROM pg_partition_tree('parted_self_fk'))
+ORDER BY cr.relname, co.conname, p.conname;
+    relname     |           conname           | convalidated |          conparent          | convalidated |   foreignrel   
+----------------+-----------------------------+--------------+-----------------------------+--------------+----------------
+ part1_self_fk  | parted_self_fk_id_abc_fkey  | t            | parted_self_fk_id_abc_fkey  | t            | parted_self_fk
+ part2_self_fk  | parted_self_fk_id_abc_fkey  | t            | parted_self_fk_id_abc_fkey  | t            | parted_self_fk
+ part32_self_fk | parted_self_fk_id_abc_fkey  | t            | parted_self_fk_id_abc_fkey  | t            | parted_self_fk
+ part33_self_fk | parted_self_fk_id_abc_fkey  | t            | parted_self_fk_id_abc_fkey  | t            | parted_self_fk
+ part3_self_fk  | parted_self_fk_id_abc_fkey  | t            | parted_self_fk_id_abc_fkey  | t            | parted_self_fk
+ parted_self_fk | parted_self_fk_id_abc_fkey  | t            |                             |              | parted_self_fk
+ parted_self_fk | parted_self_fk_id_abc_fkey1 | t            | parted_self_fk_id_abc_fkey  | t            | part1_self_fk
+ parted_self_fk | parted_self_fk_id_abc_fkey2 | t            | parted_self_fk_id_abc_fkey  | t            | part2_self_fk
+ parted_self_fk | parted_self_fk_id_abc_fkey3 | t            | parted_self_fk_id_abc_fkey  | t            | part3_self_fk
+ parted_self_fk | parted_self_fk_id_abc_fkey4 | t            | parted_self_fk_id_abc_fkey3 | t            | part32_self_fk
+ parted_self_fk | parted_self_fk_id_abc_fkey5 | t            | parted_self_fk_id_abc_fkey3 | t            | part33_self_fk
+(11 rows)
 
 -- detach and re-attach multiple times just to ensure everything is kosher
 ALTER TABLE parted_self_fk DETACH PARTITION part2_self_fk;
+\d+ part2_self_fk
+                              Table "public.part2_self_fk"
+ Column |  Type  | Collation | Nullable | Default | Storage | Stats target | Description 
+--------+--------+-----------+----------+---------+---------+--------------+-------------
+ id     | bigint |           | not null |         | plain   |              | 
+ id_abc | bigint |           |          |         | plain   |              | 
+Indexes:
+    "part2_self_fk_pkey" PRIMARY KEY, btree (id)
+
+INSERT INTO part2_self_fk VALUES (16, 9);	-- good, but it'll prevent the attach below
+ALTER TABLE parted_self_fk ATTACH PARTITION part2_self_fk FOR VALUES FROM (10) TO (20);
+ERROR:  insert or update on table "part2_self_fk" violates foreign key constraint "parted_self_fk_id_abc_fkey"
+DETAIL:  Key (id_abc)=(9) is not present in table "parted_self_fk".
+DELETE FROM part2_self_fk WHERE id = 16;
 ALTER TABLE parted_self_fk ATTACH PARTITION part2_self_fk FOR VALUES FROM (10) TO (20);
+INSERT INTO parted_self_fk VALUES (16, 9);	-- error: referenced doesn't exist
+ERROR:  insert or update on table "part2_self_fk" violates foreign key constraint "parted_self_fk_id_abc_fkey"
+DETAIL:  Key (id_abc)=(9) is not present in table "parted_self_fk".
+DELETE FROM parted_self_fk WHERE id = 3 RETURNING *;	-- error: reference remains
+ERROR:  update or delete on table "part1_self_fk" violates foreign key constraint "parted_self_fk_id_abc_fkey1" on table "parted_self_fk"
+DETAIL:  Key (id)=(3) is still referenced from table "parted_self_fk".
 ALTER TABLE parted_self_fk DETACH PARTITION part2_self_fk;
 ALTER TABLE parted_self_fk ATTACH PARTITION part2_self_fk FOR VALUES FROM (10) TO (20);
-SELECT cr.relname, co.conname, co.contype, co.convalidated,
+ALTER TABLE parted_self_fk DETACH PARTITION part3_self_fk;
+ALTER TABLE parted_self_fk ATTACH PARTITION part3_self_fk FOR VALUES FROM (30) TO (40);
+ALTER TABLE part3_self_fk DETACH PARTITION part33_self_fk;
+ALTER TABLE part3_self_fk ATTACH PARTITION part33_self_fk FOR VALUES FROM (30) TO (40);
+SELECT cr.relname, co.conname, co.convalidated,
        p.conname AS conparent, p.convalidated, cf.relname AS foreignrel
 FROM pg_constraint co
 JOIN pg_class cr ON cr.oid = co.conrelid
 LEFT JOIN pg_class cf ON cf.oid = co.confrelid
 LEFT JOIN pg_constraint p ON p.oid = co.conparentid
-WHERE cr.oid IN (SELECT relid FROM pg_partition_tree('parted_self_fk'))
-ORDER BY co.contype, cr.relname, co.conname, p.conname;
-    relname     |          conname           | contype | convalidated |         conparent          | convalidated |   foreignrel   
-----------------+----------------------------+---------+--------------+----------------------------+--------------+----------------
- part1_self_fk  | parted_self_fk_id_abc_fkey | f       | t            | parted_self_fk_id_abc_fkey | t            | parted_self_fk
- part2_self_fk  | parted_self_fk_id_abc_fkey | f       | t            | parted_self_fk_id_abc_fkey | t            | parted_self_fk
- part32_self_fk | parted_self_fk_id_abc_fkey | f       | t            | parted_self_fk_id_abc_fkey | t            | parted_self_fk
- part33_self_fk | parted_self_fk_id_abc_fkey | f       | t            | parted_self_fk_id_abc_fkey | t            | parted_self_fk
- part3_self_fk  | parted_self_fk_id_abc_fkey | f       | t            | parted_self_fk_id_abc_fkey | t            | parted_self_fk
- parted_self_fk | parted_self_fk_id_abc_fkey | f       | t            |                            |              | parted_self_fk
- part1_self_fk  | part1_self_fk_pkey         | p       | t            | parted_self_fk_pkey        | t            | 
- part2_self_fk  | part2_self_fk_pkey         | p       | t            | parted_self_fk_pkey        | t            | 
- part32_self_fk | part32_self_fk_pkey        | p       | t            | part3_self_fk_pkey         | t            | 
- part33_self_fk | part33_self_fk_pkey        | p       | t            | part3_self_fk_pkey         | t            | 
- part3_self_fk  | part3_self_fk_pkey         | p       | t            | parted_self_fk_pkey        | t            | 
- parted_self_fk | parted_self_fk_pkey        | p       | t            |                            |              | 
-(12 rows)
+WHERE co.contype = 'f' AND
+      cr.oid IN (SELECT relid FROM pg_partition_tree('parted_self_fk'))
+ORDER BY cr.relname, co.conname, p.conname;
+    relname     |           conname           | convalidated |          conparent          | convalidated |   foreignrel   
+----------------+-----------------------------+--------------+-----------------------------+--------------+----------------
+ part1_self_fk  | parted_self_fk_id_abc_fkey  | t            | parted_self_fk_id_abc_fkey  | t            | parted_self_fk
+ part2_self_fk  | parted_self_fk_id_abc_fkey  | t            | parted_self_fk_id_abc_fkey  | t            | parted_self_fk
+ part32_self_fk | parted_self_fk_id_abc_fkey  | t            | parted_self_fk_id_abc_fkey  | t            | parted_self_fk
+ part33_self_fk | parted_self_fk_id_abc_fkey  | t            | parted_self_fk_id_abc_fkey  | t            | parted_self_fk
+ part3_self_fk  | parted_self_fk_id_abc_fkey  | t            | parted_self_fk_id_abc_fkey  | t            | parted_self_fk
+ parted_self_fk | parted_self_fk_id_abc_fkey  | t            |                             |              | parted_self_fk
+ parted_self_fk | parted_self_fk_id_abc_fkey1 | t            | parted_self_fk_id_abc_fkey  | t            | part1_self_fk
+ parted_self_fk | parted_self_fk_id_abc_fkey2 | t            | parted_self_fk_id_abc_fkey  | t            | part2_self_fk
+ parted_self_fk | parted_self_fk_id_abc_fkey3 | t            | parted_self_fk_id_abc_fkey  | t            | part3_self_fk
+ parted_self_fk | parted_self_fk_id_abc_fkey4 | t            | parted_self_fk_id_abc_fkey3 | t            | part32_self_fk
+ parted_self_fk | parted_self_fk_id_abc_fkey5 | t            | parted_self_fk_id_abc_fkey3 | t            | part33_self_fk
+(11 rows)
 
 -- Leave this table around, for pg_upgrade/pg_dump tests
 -- Test creating a constraint at the parent that already exists in partitions.
diff --git a/src/test/regress/expected/triggers.out b/src/test/regress/expected/triggers.out
index a3211056481..827816d24a9 100644
--- a/src/test/regress/expected/triggers.out
+++ b/src/test/regress/expected/triggers.out
@@ -2713,11 +2713,13 @@ select tgrelid::regclass, rtrim(tgname, '0123456789') as tgname,
   tgfoid::regproc, tgenabled
   from pg_trigger where tgrelid in ('parent'::regclass, 'child1'::regclass)
   order by tgrelid::regclass::text, tgfoid;
- tgrelid |         tgname          |       tgfoid        | tgenabled 
----------+-------------------------+---------------------+-----------
- child1  | RI_ConstraintTrigger_c_ | "RI_FKey_check_ins" | O
- child1  | RI_ConstraintTrigger_c_ | "RI_FKey_check_upd" | O
-(2 rows)
+ tgrelid |         tgname          |         tgfoid         | tgenabled 
+---------+-------------------------+------------------------+-----------
+ child1  | RI_ConstraintTrigger_c_ | "RI_FKey_check_ins"    | O
+ child1  | RI_ConstraintTrigger_c_ | "RI_FKey_check_upd"    | O
+ child1  | RI_ConstraintTrigger_a_ | "RI_FKey_noaction_del" | O
+ child1  | RI_ConstraintTrigger_a_ | "RI_FKey_noaction_upd" | O
+(4 rows)
 
 -- Before v15, this has no effect because parent has no triggers:
 alter table parent disable trigger all;
@@ -2725,11 +2727,13 @@ select tgrelid::regclass, rtrim(tgname, '0123456789') as tgname,
   tgfoid::regproc, tgenabled
   from pg_trigger where tgrelid in ('parent'::regclass, 'child1'::regclass)
   order by tgrelid::regclass::text, tgfoid;
- tgrelid |         tgname          |       tgfoid        | tgenabled 
----------+-------------------------+---------------------+-----------
- child1  | RI_ConstraintTrigger_c_ | "RI_FKey_check_ins" | O
- child1  | RI_ConstraintTrigger_c_ | "RI_FKey_check_upd" | O
-(2 rows)
+ tgrelid |         tgname          |         tgfoid         | tgenabled 
+---------+-------------------------+------------------------+-----------
+ child1  | RI_ConstraintTrigger_c_ | "RI_FKey_check_ins"    | O
+ child1  | RI_ConstraintTrigger_c_ | "RI_FKey_check_upd"    | O
+ child1  | RI_ConstraintTrigger_a_ | "RI_FKey_noaction_del" | O
+ child1  | RI_ConstraintTrigger_a_ | "RI_FKey_noaction_upd" | O
+(4 rows)
 
 drop table parent, child1;
 -- Verify that firing state propagates correctly on creation, too
diff --git a/src/test/regress/sql/foreign_key.sql b/src/test/regress/sql/foreign_key.sql
index 0d0a52375dd..6d33f4c2042 100644
--- a/src/test/regress/sql/foreign_key.sql
+++ b/src/test/regress/sql/foreign_key.sql
@@ -1438,29 +1438,55 @@ CREATE TABLE part33_self_fk (
 );
 ALTER TABLE part3_self_fk ATTACH PARTITION part33_self_fk FOR VALUES FROM (30) TO (40);
 
-SELECT cr.relname, co.conname, co.contype, co.convalidated,
+-- verify that this constraint works
+INSERT INTO parted_self_fk VALUES (1, NULL), (2, NULL), (3, NULL);
+INSERT INTO parted_self_fk VALUES (10, 1), (11, 2), (12, 3) RETURNING tableoid::regclass;
+
+INSERT INTO parted_self_fk VALUES (4, 5);	-- error: referenced doesn't exist
+DELETE FROM parted_self_fk WHERE id = 1 RETURNING *;	-- error: reference remains
+
+SELECT cr.relname, co.conname, co.convalidated,
        p.conname AS conparent, p.convalidated, cf.relname AS foreignrel
 FROM pg_constraint co
 JOIN pg_class cr ON cr.oid = co.conrelid
 LEFT JOIN pg_class cf ON cf.oid = co.confrelid
 LEFT JOIN pg_constraint p ON p.oid = co.conparentid
-WHERE cr.oid IN (SELECT relid FROM pg_partition_tree('parted_self_fk'))
-ORDER BY co.contype, cr.relname, co.conname, p.conname;
+WHERE co.contype = 'f' AND
+      cr.oid IN (SELECT relid FROM pg_partition_tree('parted_self_fk'))
+ORDER BY cr.relname, co.conname, p.conname;
 
 -- detach and re-attach multiple times just to ensure everything is kosher
 ALTER TABLE parted_self_fk DETACH PARTITION part2_self_fk;
+
+\d+ part2_self_fk
+
+INSERT INTO part2_self_fk VALUES (16, 9);	-- good, but it'll prevent the attach below
+ALTER TABLE parted_self_fk ATTACH PARTITION part2_self_fk FOR VALUES FROM (10) TO (20);
+
+DELETE FROM part2_self_fk WHERE id = 16;
 ALTER TABLE parted_self_fk ATTACH PARTITION part2_self_fk FOR VALUES FROM (10) TO (20);
+
+INSERT INTO parted_self_fk VALUES (16, 9);	-- error: referenced doesn't exist
+DELETE FROM parted_self_fk WHERE id = 3 RETURNING *;	-- error: reference remains
+
 ALTER TABLE parted_self_fk DETACH PARTITION part2_self_fk;
 ALTER TABLE parted_self_fk ATTACH PARTITION part2_self_fk FOR VALUES FROM (10) TO (20);
 
-SELECT cr.relname, co.conname, co.contype, co.convalidated,
+ALTER TABLE parted_self_fk DETACH PARTITION part3_self_fk;
+ALTER TABLE parted_self_fk ATTACH PARTITION part3_self_fk FOR VALUES FROM (30) TO (40);
+
+ALTER TABLE part3_self_fk DETACH PARTITION part33_self_fk;
+ALTER TABLE part3_self_fk ATTACH PARTITION part33_self_fk FOR VALUES FROM (30) TO (40);
+
+SELECT cr.relname, co.conname, co.convalidated,
        p.conname AS conparent, p.convalidated, cf.relname AS foreignrel
 FROM pg_constraint co
 JOIN pg_class cr ON cr.oid = co.conrelid
 LEFT JOIN pg_class cf ON cf.oid = co.confrelid
 LEFT JOIN pg_constraint p ON p.oid = co.conparentid
-WHERE cr.oid IN (SELECT relid FROM pg_partition_tree('parted_self_fk'))
-ORDER BY co.contype, cr.relname, co.conname, p.conname;
+WHERE co.contype = 'f' AND
+      cr.oid IN (SELECT relid FROM pg_partition_tree('parted_self_fk'))
+ORDER BY cr.relname, co.conname, p.conname;
 
 -- Leave this table around, for pg_upgrade/pg_dump tests