CREATE TABLEGROUP

描述

该语句用来创建表组。

表组主要用于创建一组具有相同分布特征的表，具有相同分布特征的表在进行连接操作时，可以在本地进行，避免跨节点的数据请求。

创建表组时，首先要规划好表组的用途。如果是用于普通表的属性，表组就不用分区；如果是用于分区表的属性，表组就要指定分区策略，并且要跟分区表的分区策略保持一致。

语法

CREATE TABLEGROUP [IF NOT EXISTS] tablegroup_name [PARTITION BY opt_tg_partition_option]

opt_tg_partition_option:

     KEY column_num  PARTITIONS INTNUM
   | HASH PARTITIONS INTNUM
   | RANGE {PARTITION partition_name VALUES LESS THAN range_partition_expr, ...}
   | RANGE COLUMNS column_num {PARTITION partition_name VALUES LESS THAN range_partition_expr, ...}
   | LIST {PARTITION partition_name VALUES IN list_partition_expr, ...}
   | LIST COLUMNS column_num {PARTITION partition_name VALUES IN list_partition_expr, ...}

参数解释

示例

• 创建名为 myTableGroup1 的表组。

  obclient> CREATE TABLEGROUP myTableGroup1;
  Query OK, 0 rows affected
  
  obclient> CREATE TABLE myt1 (c1 int, c2 int ) TABLEGROUP = myTableGroup1;
  Query OK, 0 rows affected
  
  obclient> CREATE TABLE myt2 (c1 int, c2 int ) TABLEGROUP = myTableGroup1;
  Query OK, 0 rows affected
  

• 创建 HASH 分区的表组 tgh，同时创建 HASH 分区的表，其中 ttgh 与 ttgh2 且分区个数相同，ttgh3 且分区个数不相同，发生报错。

  obclient> CREATE TABLEGROUP tgh PARTITION BY HASH PARTITIONS 10;
  Query OK, 0 rows affected
  
  obclient> CREATE TABLE ttgh(c1 INT, c2 INT) TABLEGROUP = tgh PARTITION BY HASH(c1) PARTITIONS 10;
  Query OK, 0 rows affected
  
  obclient> CREATE TABLE ttgh2(c1 INT, c2 INT) TABLEGROUP = tgh PARTITION BY HASH(c1) PARTITIONS 10;
  Query OK, 0 rows affected
  
  obclient> CREATE TABLE ttgh3(c1 INT, c2 INT) TABLEGROUP = tgh PARTITION BY HASH(c1) PARTITIONS 5;
  ErrorCode = 4179, SQLState = HY000, Details = range partition number not match not allowed
  

• 创建 Range 分区的表组。

  obclient> CREATE TABLEGROUP tblgroup1 PARTITION BY RANGE
              ( PARTITION p0 VALUES LESS THAN(100),
                PARTITION p1 VALUES LESS THAN(200)
               );
  Query OK, 0 rows affected
  

• 创建 Range Columns 分区的表组。

  obclient> CREATE TABLEGROUP tblgroup2 PARTITION BY RANGE COLUMNS 1 
              ( PARTITION p0 VALUES LESS THAN(100),
                PARTITION p1 VALUES LESS THAN(200)
               );
  Query OK, 0 rows affected
  

• 创建 List 分区的表组。

  obclient> CREATE TABLEGROUP tblgroup3 PARTITION BY LIST
              ( PARTITION p_northwest VALUES IN(100),
                PARTITION p_southwest VALUES IN(200)
              );
  Query OK, 0 rows affected
  

• 创建 List Columns 分区的表组。

  obclient> CREATE TABLEGROUP tblgroup4 PARTITION BY LIST COLUMNS 1 
              ( PARTITION p_northwest VALUES IN('OR', 'WA'),
                PARTITION p_southwest VALUES IN('AZ', 'UT', 'NM')
              );
  Query OK, 0 rows affected
  

• 创建 Hash 分区的表组。

  obclient> CREATE TABLEGROUP tblgroup5 PARTITION BY HASH PARTITIONS 10;
  Query OK, 0 rows affected
  

• 创建 Key 分区的表组。

  obclient> CREATE TABLEGROUP tblgroup6 PARTITION BY KEY 1 PARTITIONS 10;
  Query OK, 0 rows affected