We should add support for REPLACE INTO SELECT FROM.

CREATE TABLE t1(
name VARCHAR(50),
population INT
) ENGINE=Columnstore;
INSERT INTO t1(name,population)
VALUES('New York', 8008278),
('Los Angeles', 3694825),
('San Diego', 1223405);

CREATE TABLE t2(
name VARCHAR(50),
population INT
) ENGINE=Columnstore;
INSERT INTO t2(name,population)
VALUES('San Fransisco', 4694825);

REPLACE INTO
t1(name,population)
SELECT
name,
population
FROM
t2;
ERROR 1178 (42000): The storage engine for the table doesn't support REPLACE statement is not supported in Columnstore.