Simply using a partition_options clause with ALTER TABLE on a partitioned table repartitions the table according to the partitioning scheme defined by the partition_options. 只需在分区表上使用带有ALTER TABLE的partition_options子句，即可根据partition_options定义的分区方案重新分区表。This clause always begins with PARTITION BY, and follows the same syntax and other rules as apply to the partition_options clause for CREATE TABLE (for more detailed information, see Section 13.1.20, “CREATE TABLE Statement”), and can also be used to partition an existing table that is not already partitioned. 该子句始终以PARTITION BY开头，并遵循适用于CREATE TABLE的partition_options子句相同的语法和其他规则（有关更多详细信息，请参阅第13.1.20节，“CREATE TABLE语句”），还可用于对尚未分区的现有表进行分区。For example, consider a (nonpartitioned) table defined as shown here:例如，考虑如下定义的（非分区）表：

CREATE TABLE t1 (
    id INT,
    year_col INT
);

This table can be partitioned by HASH, using the id column as the partitioning key, into 8 partitions by means of this statement:通过以下语句，可以使用id列作为分区键，通过HASH将该表分区为8个分区：

ALTER TABLE t1
    PARTITION BY HASH(id)
    PARTITIONS 8;

MySQL supports an ALGORITHM option with [SUB]PARTITION BY [LINEAR] KEY. MySQL支持通过[SUB]PARTITION BY [LINEAR] KEY（按[LINEAR]键进行[SUB]分区）的ALGORITHM（算法）选项。ALGORITHM=1 causes the server to use the same key-hashing functions as MySQL 5.1 when computing the placement of rows in partitions; ALGORITHM=2 means that the server employs the key-hashing functions implemented and used by default for new KEY partitioned tables in MySQL 5.5 and later. ALGORITHM=1导致服务器在计算分区中的行位置时使用与MySQL 5.1相同的密钥散列函数；ALGORITHM=2意味着服务器使用默认情况下为MySQL 5.5及更高版本中的新密钥分区表实现和使用的密钥散列函数。(Partitioned tables created with the key-hashing functions employed in MySQL 5.5 and later cannot be used by a MySQL 5.1 server.) （使用MySQL 5.5及更高版本中使用的密钥散列函数创建的分区表不能由MySQL 5.1服务器使用。）Not specifying the option has the same effect as using ALGORITHM=2. 不指定该选项的效果与使用ALGORITHM=2的效果相同。This option is intended for use chiefly when upgrading or downgrading [LINEAR] KEY partitioned tables between MySQL 5.1 and later MySQL versions, or for creating tables partitioned by KEY or LINEAR KEY on a MySQL 5.5 or later server which can be used on a MySQL 5.1 server.此选项主要用于在MySQL 5.1和更高版本的MySQL之间升级或降级[LINEAR] KEY分区表，或在MySQL 5.5或更高版本的服务器上创建可在MySQL 5.1服务器上使用的按KEY或LINEAR KEY分区的表。

The table that results from using an ALTER TABLE ... PARTITION BY statement must follow the same rules as one created using CREATE TABLE ... PARTITION BY. 使用ALTER TABLE ... PARTITION BY语句生成的表必须遵循与使用CREATE TABLE ... PARTITION BY创建的表相同的规则。This includes the rules governing the relationship between any unique keys (including any primary key) that the table might have, and the column or columns used in the partitioning expression, as discussed in Section 24.6.1, “Partitioning Keys, Primary Keys, and Unique Keys”. 这包括管理表可能具有的任何唯一键（包括任何主键）与分区表达式中使用的列之间关系的规则，如第24.6.1节，“分区键、主键和唯一键”中所述。The CREATE TABLE ... PARTITION BY rules for specifying the number of partitions also apply to ALTER TABLE ... PARTITION BY.用于指定分区数的CREATE TABLE ... PARTITION BY规则也适用于ALTER TABLE ... PARTITION BY。

The partition_definition clause for ALTER TABLE ADD PARTITION supports the same options as the clause of the same name for the CREATE TABLE statement. ALTER TABLE ADD PARTITION的partition_definition子句支持与CREATE TABLE语句的同名子句相同的选项。(See Section 13.1.20, “CREATE TABLE Statement”, for the syntax and description.) （有关语法和说明，请参阅第13.1.20节，“CREATE TABLE语句”。）Suppose that you have the partitioned table created as shown here:假设已创建分区表，如下所示：

CREATE TABLE t1 (
    id INT,
    year_col INT
)
PARTITION BY RANGE (year_col) (
    PARTITION p0 VALUES LESS THAN (1991),
    PARTITION p1 VALUES LESS THAN (1995),
    PARTITION p2 VALUES LESS THAN (1999)
);

You can add a new partition p3 to this table for storing values less than 2002 as follows:您可以将新分区p3添加到此表中，以存储小于2002的值，如下所示：

ALTER TABLE t1 ADD PARTITION (PARTITION p3 VALUES LESS THAN (2002));

DROP PARTITION can be used to drop one or more RANGE or LIST partitions. DROP PARTITION可用于删除一个或多个RANGE分区或LIST分区。This statement cannot be used with HASH or KEY partitions; instead, use COALESCE PARTITION (see later in this section). 此语句不能与HASH分区或KEY分区一起使用；而是使用COALESCE PARTITION（参见本节后面的内容）。Any data that was stored in the dropped partitions named in the partition_names list is discarded. 存储在partition_names列表中命名的已删除分区中的任何数据都将被丢弃。For example, given the table t1 defined previously, you can drop the partitions named p0 and p1 as shown here:例如，给定前面定义的表t1，可以删除名为p0和p1的分区，如下所示：

ALTER TABLE t1 DROP PARTITION p0, p1;

ADD PARTITION and DROP PARTITION do not currently support IF [NOT] EXISTS.ADD PARTITION和DROP PARTITION当前不支持IF [NOT] EXISTS。

The DISCARD PARTITION ... TABLESPACE and IMPORT PARTITION ... TABLESPACE options extend the Transportable Tablespace feature to individual InnoDB table partitions. DISCARD PARTITION ... TABLESPACE和IMPORT PARTITION ... TABLESPACE选项将可传输表空间功能扩展到单个InnoDB表分区。Each InnoDB table partition has its own tablespace file (.ibd file). 每个InnoDB表分区都有自己的表空间文件（.ibd文件）。The Transportable Tablespace feature makes it easy to copy the tablespaces from a running MySQL server instance to another running instance, or to perform a restore on the same instance. 可传输表空间特性使得将表空间从一个正在运行的MySQL服务器实例复制到另一个正在运行的实例或在同一实例上执行恢复变得非常容易。Both options take a comma-separated list of one or more partition names. 这两个选项都采用一个或多个分区名称的逗号分隔列表。For example:例如：

ALTER TABLE t1 DISCARD PARTITION p2, p3 TABLESPACE;

ALTER TABLE t1 IMPORT PARTITION p2, p3 TABLESPACE;

When running DISCARD PARTITION ... TABLESPACE and IMPORT PARTITION ... TABLESPACE on subpartitioned tables, both partition and subpartition names are allowed. 当在子分区表上运行DISCARD PARTITION ... TABLESPACE和IMPORT PARTITION ... TABLESPACE时，既允许使用分区名称，又允许使用子分区名称。When a partition name is specified, subpartitions of that partition are included.指定分区名称时，将包括该分区的子分区。

The Transportable Tablespace feature also supports copying or restoring partitioned InnoDB tables. 可传输表空间功能还支持复制或恢复已分区的InnoDB表。For more information, see Section 15.6.1.3, “Importing InnoDB Tables”.有关更多信息，请参阅第15.6.1.3节，“导入InnoDB表”。

Renames of partitioned tables are supported. 支持对分区表进行重命名。You can rename individual partitions indirectly using ALTER TABLE ... REORGANIZE PARTITION; however, this operation copies the partition's data.您可以使用ALTER TABLE ... REORGANIZE PARTITION间接重命名各个分区；但是，此操作复制分区的数据。

To delete rows from selected partitions, use the TRUNCATE PARTITION option. 要从选定分区中删除行，请使用TRUNCATE PARTITION选项。This option takes a list of one or more comma-separated partition names. 此选项接受一个或多个以逗号分隔的分区名称的列表。Consider the table t1 created by this statement:考虑由该语句创建的表t1：

CREATE TABLE t1 (
    id INT,
    year_col INT
)
PARTITION BY RANGE (year_col) (
    PARTITION p0 VALUES LESS THAN (1991),
    PARTITION p1 VALUES LESS THAN (1995),
    PARTITION p2 VALUES LESS THAN (1999),
    PARTITION p3 VALUES LESS THAN (2003),
    PARTITION p4 VALUES LESS THAN (2007)
);

To delete all rows from partition p0, use the following statement:要删除分区p0中的所有行，请使用以下语句：

ALTER TABLE t1 TRUNCATE PARTITION p0;

The statement just shown has the same effect as the following DELETE statement:刚才显示的语句与以下DELETE语句具有相同的效果：

DELETE FROM t1 WHERE year_col < 1991;

When truncating multiple partitions, the partitions do not have to be contiguous: This can greatly simplify delete operations on partitioned tables that would otherwise require very complex WHERE conditions if done with DELETE statements. 在截断多个分区时，分区不必是连续的：这可以大大简化分区表上的删除操作，否则，如果使用DELETE语句，则需要非常复杂的WHERE条件。For example, this statement deletes all rows from partitions p1 and p3:例如，此语句删除分区p1和p3中的所有行：

ALTER TABLE t1 TRUNCATE PARTITION p1, p3;

An equivalent DELETE statement is shown here:此处显示了等效的DELETE语句：

DELETE FROM t1 WHERE
    (year_col >= 1991 AND year_col < 1995)
    OR
    (year_col >= 2003 AND year_col < 2007);

If you use the ALL keyword in place of the list of partition names, the statement acts on all table partitions.如果使用ALL关键字代替分区名称列表，则该语句将作用于所有表分区。

TRUNCATE PARTITION merely deletes rows; it does not alter the definition of the table itself, or of any of its partitions.TRUNCATE PARTITION只删除行；它不会改变表本身或其任何分区的定义。

To verify that the rows were dropped, check the INFORMATION_SCHEMA.PARTITIONS table, using a query such as this one:要验证行是否已被删除，请使用以下查询检查INFORMATION_SCHEMA.PARTITIONS表：

SELECT PARTITION_NAME, TABLE_ROWS
    FROM INFORMATION_SCHEMA.PARTITIONS
    WHERE TABLE_NAME = 't1';

COALESCE PARTITION can be used with a table that is partitioned by HASH or KEY to reduce the number of partitions by number. COALESCE PARTITION可以与按哈希或键分区的表一起使用，以按数量减少分区的数量。Suppose that you have created table t2 as follows:假设您创建了表t2，如下所示：

CREATE TABLE t2 (
    name VARCHAR (30),
    started DATE
)
PARTITION BY HASH( YEAR(started) )
PARTITIONS 6;

To reduce the number of partitions used by t2 from 6 to 4, use the following statement:要将t2使用的分区数从6减少到4，请使用以下语句：

ALTER TABLE t2 COALESCE PARTITION 2;

The data contained in the last number partitions is merged into the remaining partitions. 最后number分区中包含的数据将合并到其余分区中。In this case, partitions 4 and 5 are merged into the first 4 partitions (the partitions numbered 0, 1, 2, and 3).在这种情况下，分区4和5合并到前4个分区中（编号为0、1、2和3的分区）。

To change some but not all the partitions used by a partitioned table, you can use REORGANIZE PARTITION. 要更改分区表使用的部分分区，但不是全部分区，可以使用REORGANIZE PARTITION。This statement can be used in several ways:此语句可通过多种方式使用：

For more detailed information about and examples of ALTER TABLE ... REORGANIZE PARTITION statements, see Section 24.3.1, “Management of RANGE and LIST Partitions”.有关ALTER TABLE ... REORGANIZE PARTITION语句的更多详细信息和示例，请参阅第24.3.1节，“范围和列表分区的管理”。

To exchange a table partition or subpartition with a table, use the ALTER TABLE ... EXCHANGE PARTITION statement—that is, to move any existing rows in the partition or subpartition to the nonpartitioned table, and any existing rows in the nonpartitioned table to the table partition or subpartition.要与表交换表分区或子分区，请使用ALTER TABLE ... EXCHANGE PARTITION语句，即将分区或子分区中的任何现有行移动到非分区表，并将非分区表中的任何现有行移动到表分区或子分区。

For usage information and examples, see Section 24.3.3, “Exchanging Partitions and Subpartitions with Tables”.有关使用信息和示例，请参阅第24.3.3节，“用表交换分区和子分区”。

Several options provide partition maintenance and repair functionality analogous to that implemented for nonpartitioned tables by statements such as CHECK TABLE and REPAIR TABLE (which are also supported for partitioned tables; for more information, see Section 13.7.3, “Table Maintenance Statements”). 有几个选项提供分区维护和修复功能，类似于CHECK TABLE和REPAIR TABLE等语句为非分区表实现的功能（分区表也支持这些功能；有关更多信息，请参阅第13.7.3节，“表维护语句”）。These include ANALYZE PARTITION, CHECK PARTITION, OPTIMIZE PARTITION, REBUILD PARTITION, and REPAIR PARTITION. 这些包括ANALYZE PARTITION（分析分区）、CHECK PARTITION（检查分区）、OPTIMIZE PARTITION（优化分区）、REBUILD PARTITION（重建分区）和REPAIR PARTITION（修复分区）。Each of these options takes a partition_names clause consisting of one or more names of partitions, separated by commas. 这些选项中的每一个都采用一个partition_names子句，该子句由一个或多个分区名称组成，用逗号分隔。The partitions must already exist in the target table. 分区必须已经存在于目标表中。You can also use the ALL keyword in place of partition_names, in which case the statement acts on all table partitions. 您还可以使用ALL关键字代替partition_names，在这种情况下，该语句作用于所有表分区。For more information and examples, see Section 24.3.4, “Maintenance of Partitions”.有关更多信息和示例，请参阅第24.3.4节，“分区维护”。

InnoDB does not currently support per-partition optimization; ALTER TABLE ... OPTIMIZE PARTITION causes the entire table to rebuilt and analyzed, and an appropriate warning to be issued. InnoDB目前不支持每个分区的优化；ALTER TABLE ... OPTIMIZE PARTITION会导致重建和分析整个表，并发出相应的警告。(Bug #11751825, Bug #42822) To work around this problem, use ALTER TABLE ... REBUILD PARTITION and ALTER TABLE ... ANALYZE PARTITION instead.要绕过此问题，请改用ALTER TABLE ... REBUILD PARTITION和ALTER TABLE ... ANALYZE PARTITION。

The ANALYZE PARTITION, CHECK PARTITION, OPTIMIZE PARTITION, and REPAIR PARTITION options are not supported for tables which are not partitioned.未分区的表不支持ANALYZE PARTITION（分析分区）、CHECK PARTITION（检查分区）、OPTIMIZE PARTITION（优化分区）和REPAIR PARTITION选项。

REMOVE PARTITIONING enables you to remove a table's partitioning without otherwise affecting the table or its data. REMOVE PARTITIONING使您能够移除表的分区，而不会影响表或其数据。This option can be combined with other ALTER TABLE options such as those used to add, drop, or rename columns or indexes.此选项可以与其他ALTER TABLE选项组合使用，例如用于添加、删除或重命名列或索引的选项。

Using the ENGINE option with ALTER TABLE changes the storage engine used by the table without affecting the partitioning. 将ENGINE选项与ALTER TABLE一起使用会更改表使用的存储引擎，而不会影响分区。The target storage engine must provide its own partitioning handler. 目标存储引擎必须提供自己的分区处理程序。Only the InnoDB and NDB storage engines have native partitioning handlers; NDB is not currently supported in MySQL 8.0.只有InnoDB和NDB存储引擎具有本机分区处理程序；MySQL 8.0目前不支持NDB。