Modify the SHARDING attribute of a table group

After you create a table group, you can modify the SHARDING attribute of the table group based on your business adjustments.

Limitations

Do not execute the ALTER TABLEGROUP statement to modify the SHARDING attribute during the upgrade of OceanBase Database.

Rules

Before you modify the SHARDING attribute of a table group, check whether the table group contains tables and the partition information of the tables. For more information, see View table group information.

If the table group does not contain tables, you can modify the SHARDING attribute of the table group as needed. If the table group contains tables, the modification is subject to the following rules:

• If you want to change the SHARDING attribute of the table group to NONE, you can do so without considering the partition definitions of the tables in the table group.

• If you want to change the SHARDING attribute of the table group to PARTITION, the partitioned tables must meet the following requirements:

  • If all tables in the table group are non-partitioned tables, the modification is allowed.

  • If the table group contains both partitioned and non-partitioned tables, the modification is not allowed.

  • If the table group contains only partitioned tables, the partition types, number of partitions, and partition values of all tables must be the same.

• If you want to change the SHARDING attribute of the table group to ADAPTIVE, the partitioned tables must meet the following requirements:

  • If all tables in the table group are non-partitioned tables, the modification is allowed.

  • If the table group contains both partitioned and non-partitioned tables, the modification is not allowed.

  • If the table group contains both partitioned tables and subpartitioned tables, the modification is not allowed.

  • If all tables in the table group are partitioned tables, the partition types, number of partitions, and partition values of all tables must be the same.

  • If all tables in the table group are subpartitioned tables, the partition types, number of partitions, and partition values of all partitioned tables and subpartitioned tables must be the same.

Modify the table group attribute

Execute the following statement to modify the SHARDING attribute of a table group:

ALTER TABLEGROUP tablegroup_name tablegroup_option;

tablegroup_option:
SHARDING = 'NONE'
SHARDING = 'PARTITION'
SHARDING = 'ADAPTIVE'

The statement parameters are described as follows:

• Make sure that you have the global ALTER privilege before you execute the statement.

• tablegroup_name: the name of the table group whose attribute is to be modified.

• SHARDING: the table group attribute. The modification is subject to the preceding rules.

Here is an example of modifying the table group attribute:

1. Create a table group named tblgroup1 with the SHARDING attribute set to PARTITION.

   CREATE TABLEGROUP tblgroup1 SHARDING = 'PARTITION'; 
   

2. Create two partitioned tables named tbl1 and tbl2 with the same partition definition, and add them to the tblgroup1 table group.

   CREATE TABLE tbl1 (col1 BIGINT PRIMARY KEY,col2 VARCHAR(50)) TABLEGROUP = tblgroup1
   PARTITION BY LIST(col1)
   (PARTITION p0 VALUES IN (1, 2, 3),
   PARTITION p1 VALUES IN (5, 6),
   PARTITION p2 VALUES IN (DEFAULT)
   );
   

   CREATE TABLE tbl2 (col1 BIGINT PRIMARY KEY,col2 VARCHAR(50)) TABLEGROUP = tblgroup1
   PARTITION BY LIST(col1)
   (PARTITION p0 VALUES IN (1, 2, 3),
   PARTITION p1 VALUES IN (5, 6),
   PARTITION p2 VALUES IN (DEFAULT)
   );
   

3. Change the SHARDING attribute of the tblgroup1 table group to ADAPTIVE.

   ALTER TABLEGROUP tblgroup1 SHARDING = "ADAPTIVE";
   

4. View the table group attribute.

   SHOW TABLEGROUPS WHERE tablegroup_name = 'tblgroup1';
   

   The result is as follows:

   +-----------------+------------+---------------+----------+
   | Tablegroup_name | Table_name | Database_name | Sharding |
   +-----------------+------------+---------------+----------+
   | tblgroup1       | tbl1       | test          | ADAPTIVE |
   | tblgroup1       | tbl2       | test          | ADAPTIVE |
   +-----------------+------------+---------------+----------+
   2 rows in set
   

   The tbl1 and tbl2 tables in the table group are all partitioned tables, and their partition types, number of partitions, and partition values are the same, which meets the modification requirements.

References

• Overview of table groups

• Create a table group

• Query information about a table group

• Add tables to a table group

• Manage tables in a table group

• Drop a table group