修改聚类键

更改表的聚类键。

另请参阅： 删除聚类键

语法

ALTER TABLE [ IF EXISTS ] <name> CLUSTER BY ( <expr1> [ , <expr2> ... ] )

示例

-- 创建表
CREATE TABLE IF NOT EXISTS playground(a int, b int);

-- 通过列添加聚类键
ALTER TABLE playground CLUSTER BY(b,a);

INSERT INTO playground VALUES(0,3),(1,1);
INSERT INTO playground VALUES(1,3),(2,1);
INSERT INTO playground VALUES(4,4);

SELECT * FROM playground ORDER BY b,a;
SELECT * FROM clustering_information('db1','playground');

-- 删除聚类键
ALTER TABLE playground DROP CLUSTER KEY;

-- 通过表达式添加聚类键
ALTER TABLE playground CLUSTER BY(rand()+a);