Tighten integrity checks on ALTER TABLE ... ALTER COLUMN ... RENAME.

When a column is renamed, we recursively rename the same column in
all descendent tables.  But if one of those tables also inherits that
column from a table outside the inheritance hierarchy rooted at the
named table, we must throw an error.  The previous coding correctly
prohibited the rename when the parent had inherited the column from
elsewhere, but overlooked the case where the parent was OK but a child
table also inherited the same column from a second, unrelated parent.

For now, not backpatched due to lack of complaints from the field.

KaiGai Kohei, with further changes by me.
Reviewed by Bernd Helme and Tom Lane.

2 files changed, 133 insertions, 0 deletions

diff --git a/src/test/regress/expected/inherit.out b/src/test/regress/expected/inherit.out
index 9c83a32f934..98c8a79a7e2 100644
--- a/src/test/regress/expected/inherit.out
+++ b/src/test/regress/expected/inherit.out
@@ -1053,3 +1053,97 @@ NOTICE:  merging column "a" with inherited definition
 ERROR:  column "a" has a storage parameter conflict
 DETAIL:  MAIN versus EXTENDED
 DROP TABLE t1, t2, t3, t4, t12_storage, t12_comments, t1_inh, t13_inh, t13_like, t_all;
+-- Test for renaming in simple multiple inheritance
+CREATE TABLE t1 (a int, b int);
+CREATE TABLE s1 (b int, c int);
+CREATE TABLE ts (d int) INHERITS (t1, s1);
+NOTICE:  merging multiple inherited definitions of column "b"
+ALTER TABLE t1 RENAME a TO aa;
+ALTER TABLE t1 RENAME b TO bb;                -- to be failed
+ERROR:  cannot rename inherited column "b"
+ALTER TABLE ts RENAME aa TO aaa;      -- to be failed
+ERROR:  cannot rename inherited column "aa"
+ALTER TABLE ts RENAME d TO dd;
+\d+ ts
+                  Table "public.ts"
+ Column |  Type   | Modifiers | Storage | Description 
+--------+---------+-----------+---------+-------------
+ aa     | integer |           | plain   | 
+ b      | integer |           | plain   | 
+ c      | integer |           | plain   | 
+ dd     | integer |           | plain   | 
+Inherits: t1,
+          s1
+Has OIDs: no
+
+DROP TABLE ts;
+-- Test for renaming in diamond inheritance
+CREATE TABLE t2 (x int) INHERITS (t1);
+CREATE TABLE t3 (y int) INHERITS (t1);
+CREATE TABLE t4 (z int) INHERITS (t2, t3);
+NOTICE:  merging multiple inherited definitions of column "aa"
+NOTICE:  merging multiple inherited definitions of column "b"
+ALTER TABLE t1 RENAME aa TO aaa;
+\d+ t4
+                  Table "public.t4"
+ Column |  Type   | Modifiers | Storage | Description 
+--------+---------+-----------+---------+-------------
+ aaa    | integer |           | plain   | 
+ b      | integer |           | plain   | 
+ x      | integer |           | plain   | 
+ y      | integer |           | plain   | 
+ z      | integer |           | plain   | 
+Inherits: t2,
+          t3
+Has OIDs: no
+
+CREATE TABLE ts (d int) INHERITS (t2, s1);
+NOTICE:  merging multiple inherited definitions of column "b"
+ALTER TABLE t1 RENAME aaa TO aaaa;
+ALTER TABLE t1 RENAME b TO bb;                -- to be failed
+ERROR:  cannot rename inherited column "b"
+\d+ ts
+                  Table "public.ts"
+ Column |  Type   | Modifiers | Storage | Description 
+--------+---------+-----------+---------+-------------
+ aaaa   | integer |           | plain   | 
+ b      | integer |           | plain   | 
+ x      | integer |           | plain   | 
+ c      | integer |           | plain   | 
+ d      | integer |           | plain   | 
+Inherits: t2,
+          s1
+Has OIDs: no
+
+WITH RECURSIVE r AS (
+  SELECT 't1'::regclass AS inhrelid
+UNION ALL
+  SELECT c.inhrelid FROM pg_inherits c, r WHERE r.inhrelid = c.inhparent
+)
+SELECT a.attrelid::regclass, a.attname, a.attinhcount, e.expected
+  FROM (SELECT inhrelid, count(*) AS expected FROM pg_inherits
+        WHERE inhparent IN (SELECT inhrelid FROM r) GROUP BY inhrelid) e
+  JOIN pg_attribute a ON e.inhrelid = a.attrelid WHERE NOT attislocal
+  ORDER BY a.attrelid::regclass::text, a.attnum;
+ attrelid | attname | attinhcount | expected 
+----------+---------+-------------+----------
+ t2       | aaaa    |           1 |        1
+ t2       | b       |           1 |        1
+ t3       | aaaa    |           1 |        1
+ t3       | b       |           1 |        1
+ t4       | aaaa    |           2 |        2
+ t4       | b       |           2 |        2
+ t4       | x       |           1 |        2
+ t4       | y       |           1 |        2
+ ts       | aaaa    |           1 |        1
+ ts       | b       |           2 |        1
+ ts       | x       |           1 |        1
+ ts       | c       |           1 |        1
+(12 rows)
+
+DROP TABLE t1, s1 CASCADE;
+NOTICE:  drop cascades to 4 other objects
+DETAIL:  drop cascades to table t2
+drop cascades to table ts
+drop cascades to table t3
+drop cascades to table t4
diff --git a/src/test/regress/sql/inherit.sql b/src/test/regress/sql/inherit.sql
index 192e8604d6d..192b3e73340 100644
--- a/src/test/regress/sql/inherit.sql
+++ b/src/test/regress/sql/inherit.sql
@@ -334,3 +334,42 @@ CREATE TABLE inh_error1 () INHERITS (t1, t4);
 CREATE TABLE inh_error2 (LIKE t4 INCLUDING STORAGE) INHERITS (t1);
 
 DROP TABLE t1, t2, t3, t4, t12_storage, t12_comments, t1_inh, t13_inh, t13_like, t_all;
+
+-- Test for renaming in simple multiple inheritance
+CREATE TABLE t1 (a int, b int);
+CREATE TABLE s1 (b int, c int);
+CREATE TABLE ts (d int) INHERITS (t1, s1);
+
+ALTER TABLE t1 RENAME a TO aa;
+ALTER TABLE t1 RENAME b TO bb;                -- to be failed
+ALTER TABLE ts RENAME aa TO aaa;      -- to be failed
+ALTER TABLE ts RENAME d TO dd;
+\d+ ts
+
+DROP TABLE ts;
+
+-- Test for renaming in diamond inheritance
+CREATE TABLE t2 (x int) INHERITS (t1);
+CREATE TABLE t3 (y int) INHERITS (t1);
+CREATE TABLE t4 (z int) INHERITS (t2, t3);
+
+ALTER TABLE t1 RENAME aa TO aaa;
+\d+ t4
+
+CREATE TABLE ts (d int) INHERITS (t2, s1);
+ALTER TABLE t1 RENAME aaa TO aaaa;
+ALTER TABLE t1 RENAME b TO bb;                -- to be failed
+\d+ ts
+
+WITH RECURSIVE r AS (
+  SELECT 't1'::regclass AS inhrelid
+UNION ALL
+  SELECT c.inhrelid FROM pg_inherits c, r WHERE r.inhrelid = c.inhparent
+)
+SELECT a.attrelid::regclass, a.attname, a.attinhcount, e.expected
+  FROM (SELECT inhrelid, count(*) AS expected FROM pg_inherits
+        WHERE inhparent IN (SELECT inhrelid FROM r) GROUP BY inhrelid) e
+  JOIN pg_attribute a ON e.inhrelid = a.attrelid WHERE NOT attislocal
+  ORDER BY a.attrelid::regclass::text, a.attnum;
+
+DROP TABLE t1, s1 CASCADE;