问题整理

20200915：利用远程mysql创建表时出现报错。

CREATE TABLE test.test_perm
ENGINE = MergeTree()
ORDER BY app_id AS
SELECT *
FROM mysql('10.32.0.103:3306', 'test', 'test_perm', 'trancare', 'trancare')

Received exception from server (version 20.5.2):
Code: 44. DB::Exception: Received from localhost:9000. DB::Exception: Sorting key cannot contain nullable

0 rows in set. Elapsed: 2.246 sec.

排序字段app_id必须在mysql端定义为not null。