---

part1/bug-reproducers/5/reduced_test.sql

@@ -0,0 +1,11 @@
+CREATE TABLE t1(a PRIMARY KEY, x UNIQUE);
+CREATE TABLE t2(a PRIMARY KEY, y UNIQUE);
+
+INSERT INTO t1 VALUES ('a','m'),('b','n'),('c','o');
+INSERT INTO t2 VALUES ('b','k'),('c','l');
+
+SELECT a FROM t1
+INTERSECT
+SELECT a FROM t2;
+
+ALTER TABLE t2 ADD COLUMN extra_col;