The null safe `<=>` operator does not work, here is an example case.

CREATE TABLE t3(id INT) ENGINE=COLUMNSTORE;

CREATE TABLE t4(id INT) ENGINE=COLUMNSTORE;

SELECT *

FROM t3

LEFT JOIN

(

  SELECT *

  FROM t4

) t4 ON t3.id <=> t4.id;

"Internal Error: MCS-1000: 't3' and 'sub-query' are not joined".

This fails with the error as above. The query is generated by Tableau and other ORMs which the user can't control. It will be great to have this support implemented.