could reproduced by:
CREATE TABLE t (
name varchar(128)
) ENGINE=OLAP
UNIQUE KEY(name)
DISTRIBUTED BY HASH(name) BUCKETS 1;
insert into t values('abc');
SELECT cd
FROM
(SELECT cast(now() as string) cd FROM t) t1
JOIN
(select cast(now() as string) td from t GROUP BY now()) t2
ON t1.cd = t2.td;
ERROR 1105 (HY000): errCode = 2, detailMessage = Unexpected exception: null
4ec6aa1691