一张id为分布列的hash分布表。
gbase> create table t_hash(id int, name varchar(100))distributed by('id');
Query OK, 0 rows affected (Elapsed: 00:00:00.66)
gbase> show create table t_hash;
+--------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+--------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| t_hash | CREATE TABLE "t_hash" (
"id" int(11) DEFAULT NULL,
"name" varchar(100) DEFAULT NULL
) ENGINE=EXPRESS DISTRIBUTED BY('id') DEFAULT CHARSET=utf8 TABLESPACE='sys_tablespace' |
+--------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (Elapsed: 00:00:00.00)
重建表
该方法适合所有版本，无任何风险。
新建一张表，表结构与hash分布表一样，但去掉hash分布列
create table t_nohash(id int, name varchar(100));
insert into t_nohash select * from t_hash;
rename table t_hash to t_hash_BAK;
reanem table t_nohash to t_hash ;
如上的rename操作确认所有业务正常后，可以考虑删除t_hash_BAK表以便节省空间。
删除hash列关键字
该方法在9.5的手册里出现，86未注意，但预计能用。
gbase> drop distributed column on t_hash;
Query OK, 0 rows affected (Elapsed: 00:00:00.02)
gbase> show create table t_hash;
+--------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+--------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
| t_hash | CREATE TABLE "t_hash" (
"id" int(11) DEFAULT NULL,
"name" varchar(100) DEFAULT NULL
) ENGINE=EXPRESS DEFAULT CHARSET=utf8 TABLESPACE='sys_tablespace' |
+--------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (Elapsed: 00:00:00.00)
