MySQL 5.1 provides a number of ways to modify partitioned tables. It is possible to add, drop, redefine, merge, or split existing partitions. All of these actions can be carried out using the partitioning extensions to the
ALTER TABLEcommand (see Section 12.1.7, “
ALTER TABLESyntax”, for syntax definitions). There are also ways to obtain information about partitioned tables and partitions. We discuss these topics in the sections that follow.
For information about partition management in tables partitioned by
LIST, see Section 18.3.1, “Management of
For a discussion of managing
KEYpartitions, see Section 18.3.2, “Management of
See Section 18.3.4, “Obtaining Information About Partitions”, for a discussion of mechanisms provided in MySQL 5.1 for obtaining information about partitioned tables and partitions.
For a discussion of performing maintenance operations on partitions, see Section 18.3.3, “Maintenance of Partitions”.
In MySQL 5.1, all partitions of a partitioned table must have the same number of subpartitions, and it is not possible to change the subpartitioning once the table has been created.
ALTER TABLE ... PARTITION BY ...is available and is functional beginning with MySQL 5.1.6; previously in MySQL 5.1, this was accepted as valid syntax, but the statement did nothing.
To change a table's partitioning scheme, it is necessary only to use the
ALTER TABLEcommand with a
partition_optionsclause. This clause has the same syntax as that as used with
CREATE TABLEfor creating a partitioned table, and always begins with the keywords
PARTITION BY. Suppose that you have a table partitioned by range using the following
CREATE TABLE trb3 (id INT, name VARCHAR(50), purchased DATE) PARTITION BY RANGE( YEAR(purchased) ) ( PARTITION p0 VALUES LESS THAN (1990), PARTITION p1 VALUES LESS THAN (1995), PARTITION p2 VALUES LESS THAN (2000), PARTITION p3 VALUES LESS THAN (2005) );
To repartition this table so that it is partitioned by key into two partitions using the
idcolumn value as the basis for the key, you can use this statement:
ALTER TABLE trb3 PARTITION BY KEY(id) PARTITIONS 2;
This has the same effect on the structure of the table as dropping the table and re-creating it using
CREATE TABLE trb3 PARTITION BY KEY(id) PARTITIONS 2;.
In MySQL 5.1.7 and earlier MySQL 5.1 releases,
ALTER TABLE ... ENGINE = ...removed all partitioning from the affected table. Beginning with MySQL 5.1.8, this statement changes only the storage engine used by the table, and leaves the table's partitioning scheme intact. As of MySQL 5.1.8, use
ALTER TABLE ... REMOVE PARTITIONINGto remove a table's partitioning. See Section 12.1.7, “
Only a single
REORGANIZE PARTITION, or
COALESCE PARTITIONclause can be used in a given
ALTER TABLEstatement. If you (for example) wish to drop a partition and reorganize a table's remaining partitions, you must do so in two separate
ALTER TABLEstatements (one using
DROP PARTITIONand then a second one using