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 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, you must check whether the table group contains tables and the partitioning 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 following rules apply:

• If you want to set the SHARDING attribute to NONE, you can modify it without considering the partition definitions of the tables in the table group.

• If you want to set the SHARDING attribute to PARTITION, the following conditions must be met:

  • All tables in the table group are non-partitioned tables.

  • The table group contains both non-partitioned tables and partitioned tables.

  • All tables in the table group are first-level partitioned tables or second-level partitioned tables. In addition, the partition types, number of partitions, and partition values of the first-level partitions or second-level partitions of all tables must be the same.

• If you want to set the SHARDING attribute to ADAPTIVE, the following conditions must be met:

  • All tables in the table group are non-partitioned tables.

  • The table group contains both non-partitioned tables and partitioned tables.

  • The table group contains both first-level partitioned tables and second-level partitioned tables.

  • All first-level partitioned tables must have the same partition types, number of partitions, and partition values.

  • All second-level partitioned tables must have the same partition types, number of partitions, and partition values.

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'

Note:

• You must have the global ALTER privilege.

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

• SHARDING: the table group attribute. When you modify the attribute, follow the rules.

Example:

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

   CREATE TABLEGROUP tblgroup1 SHARDING = 'PARTITION'; 
   

2. Create two partitioned tables named tbl1 and tbl2 with the same partitions 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 first-level partitioned tables, and they have the same partition types, number of partitions, and partition values, which meets the rules. The SHARDING attribute is successfully modified.

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