postgres
diff --git a/‎src/backend/optimizer/prep/prepunion.c
Lines changed: 2 additions & 2 deletions b/‎src/backend/optimizer/prep/prepunion.c
Lines changed: 2 additions & 2 deletions
diff --git a/‎src/test/isolation/expected/alter-table-4.out
Lines changed: 57 additions & 0 deletions b/‎src/test/isolation/expected/alter-table-4.out
Lines changed: 57 additions & 0 deletions
diff --git a/‎src/test/isolation/isolation_schedule
Lines changed: 1 addition & 0 deletions b/‎src/test/isolation/isolation_schedule
Lines changed: 1 addition & 0 deletions
diff --git a/‎src/test/isolation/specs/alter-table-4.spec
Lines changed: 37 additions & 0 deletions b/‎src/test/isolation/specs/alter-table-4.spec
Lines changed: 37 additions & 0 deletions
@@ -1638,15 +1638,15 @@ make_inh_translation_list(Relation oldrelation, Relation newrelation,
 		 */
 		if (old_attno < newnatts &&
 			(att = new_tupdesc->attrs[old_attno]) != NULL &&
-			!att->attisdropped && att->attinhcount != 0 &&
+			!att->attisdropped &&
 			strcmp(attname, NameStr(att->attname)) == 0)
 			new_attno = old_attno;
 		else
 		{
 			for (new_attno = 0; new_attno < newnatts; new_attno++)
 			{
 				att = new_tupdesc->attrs[new_attno];
-				if (!att->attisdropped && att->attinhcount != 0 &&
+				if (!att->attisdropped &&
 					strcmp(attname, NameStr(att->attname)) == 0)
 					break;
 			}
 
@@ -0,0 +1,57 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1b s1delc1 s2sel s1c s2sel
+step s1b: BEGIN;
+step s1delc1: ALTER TABLE c1 NO INHERIT p;
+step s2sel: SELECT SUM(a) FROM p; <waiting ...>
+step s1c: COMMIT;
+step s2sel: <... completed>
+sum            
+
+11             
+step s2sel: SELECT SUM(a) FROM p;
+sum            
+
+1              
+
+starting permutation: s1b s1delc1 s1addc2 s2sel s1c s2sel
+step s1b: BEGIN;
+step s1delc1: ALTER TABLE c1 NO INHERIT p;
+step s2sel: SELECT SUM(a) FROM p; <waiting ...>
+step s1c: COMMIT;
+step s2sel: <... completed>
+sum            
+
+11             
+step s2sel: SELECT SUM(a) FROM p;
+sum            
+
+101            
+
+starting permutation: s1b s1dropc1 s2sel s1c s2sel
+step s1b: BEGIN;
+step s1dropc1: DROP TABLE c1;
+step s2sel: SELECT SUM(a) FROM p; <waiting ...>
+step s1c: COMMIT;
+step s2sel: <... completed>
+sum            
+
+1              
+step s2sel: SELECT SUM(a) FROM p;
+sum            
+
+1              
+
+starting permutation: s1b s1delc1 s1modc1a s2sel s1c s2sel
+step s1b: BEGIN;
+step s1delc1: ALTER TABLE c1 NO INHERIT p;
+step s1modc1a: ALTER TABLE c1 ALTER COLUMN a TYPE float;
+step s2sel: SELECT SUM(a) FROM p; <waiting ...>
+step s1c: COMMIT;
+step s2sel: <... completed>
+error in steps s1c s2sel: ERROR:  attribute "a" of relation "c1" does not match parent's type
+step s2sel: SELECT SUM(a) FROM p;
+sum            
+
+1              
@@ -56,6 +56,7 @@ test: multiple-cic
 test: alter-table-1
 test: alter-table-2
 test: alter-table-3
+test: alter-table-4
 test: create-trigger
 test: async-notify
 test: vacuum-reltuples
 
@@ -0,0 +1,37 @@
+# ALTER TABLE - Add and remove inheritance with concurrent reads
+
+setup
+{
+ CREATE TABLE p (a integer);
+ INSERT INTO p VALUES(1);
+ CREATE TABLE c1 () INHERITS (p);
+ INSERT INTO c1 VALUES(10);
+ CREATE TABLE c2 (a integer);
+ INSERT INTO c2 VALUES(100);
+}
+
+teardown
+{
+ DROP TABLE IF EXISTS c1, c2, p;
+}
+
+session "s1"
+step "s1b"	{ BEGIN; }
+step "s1delc1"	{ ALTER TABLE c1 NO INHERIT p; }
+step "s1modc1a"	{ ALTER TABLE c1 ALTER COLUMN a TYPE float; }
+step "s1addc2"	{ ALTER TABLE c2 INHERIT p; }
+step "s1dropc1"	{ DROP TABLE c1; }
+step "s1c"	{ COMMIT; }
+
+session "s2"
+step "s2sel"	{ SELECT SUM(a) FROM p; }
+
+# NO INHERIT will not be visible to concurrent select,
+# since we identify children before locking them
+permutation "s1b" "s1delc1" "s2sel" "s1c" "s2sel"
+# adding inheritance likewise is not seen if s1 commits after s2 locks p
+permutation "s1b" "s1delc1" "s1addc2" "s2sel" "s1c" "s2sel"
+# but we do cope with DROP on a child table
+permutation "s1b" "s1dropc1" "s2sel" "s1c" "s2sel"
+# this case currently results in an error; doesn't seem worth preventing
+permutation "s1b" "s1delc1" "s1modc1a" "s2sel" "s1c" "s2sel"