MySQL 5.5 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
TABLE statement. 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 19.3.1, “Management of RANGE and LIST Partitions”.
For a discussion of managing
KEYpartitions, see Section 19.3.2, “Management of HASH and KEY Partitions”.
See Section 19.3.4, “Obtaining Information About Partitions”, for a discussion of mechanisms provided in MySQL 5.5 for obtaining information about partitioned tables and partitions.
For a discussion of performing maintenance operations on partitions, see Section 19.3.3, “Maintenance of Partitions”.
In MySQL 5.5, 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.
To change a table's partitioning scheme, it is necessary only to
TABLE statement with a
partition_options clause. This clause
has the same syntax as that as used with
CREATE TABLE for 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 statement:
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
id column 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;.
ALTER TABLE ... ENGINE = ... changes only the
storage engine used by the table, and leaves the table's
partitioning scheme intact. Use
ALTER TABLE ... REMOVE
PARTITIONING to remove a table's partitioning. See
Section 13.1.7, “ALTER TABLE Syntax”.
Only a single
REORGANIZE PARTITION, or
PARTITION clause can be used in a given
TABLE statement. If you (for example) wish to drop a
partition and reorganize a table's remaining partitions,
you must do so in two separate
TABLE statements (one using
PARTITION and then a second one using
Beginning with MySQL 5.5.0, it is possible to delete all rows from
one or more selected partitions using
ALTER TABLE ...