DROP DATABASE IF EXISTS mcol_5357;
CREATE DATABASE mcol_5357;
USE mcol_5357;
CREATE TABLE t1 (a INT)engine=columnstore;
INSERT INTO t1 VALUES (1), (2), (3);
SELECT item FROM (
SELECT item FROM (SELECT a AS item FROM t1) tt
UNION ALL
SELECT item FROM (SELECT a AS item FROM t1) tt
) ttt;
item
1
2
3
1
2
3
DROP DATABASE mcol_5357;