Mysql分区表的管理与维护

数据库 2024/12/23 佚名

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改变一个表的分区方案只需使用alter table 加 partition_options 子句就可以了。和创建分区表时的create table语句很像。

创建表

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)
);

创建插入数据存储过程

delimiter $$
drop procedure if exists pr_trb3$$
create procedure pr_trb3(in begindate date,in enddate date,in tabname varchar(40))
begin
while begindate<enddate 1="" begindate="date_add(begindate,interval" delimiter="" do="" drop="" end="" execute="" from="" insert="" pre="" prepare="" s="concat_ws('" set="" stmt=""><p>调用存储过程插入数据</p><pre class="brush:sql;">call pr_trb3('1985-01-01','2004-12-31','trb3');</pre>
<p>查看数据分布</p>
<pre class="brush:sql;">select 
partition_name part, 
partition_expression expr, 
partition_description descr, 
table_rows 
from information_schema.partitions where 
table_schema = schema() 
and table_name='trb3';
+------+------------------+-------+------------+
| part | expr | descr | table_rows |
+------+------------------+-------+------------+
| p0 | YEAR(purchased) | 1990 | 1826 |
| p1 | YEAR(purchased) | 1995 | 1826 |
| p2 | YEAR(purchased) | 2000 | 1826 |
| p3 | YEAR(purchased) | 2005 | 1826 |
+------+------------------+-------+------------+
4 rows in set (0.00 sec)</pre>
<p>改变分区方案</p>
<pre class="brush:sql;">mysql> ALTER TABLE trb3 PARTITION BY KEY(id) PARTITIONS 4;
Query OK, 7304 rows affected (0.07 sec)
Records: 7304 Duplicates: 0 Warnings: 0</pre>
<p>查看数据</p>
<pre class="brush:sql;">select 
partition_name part, 
partition_expression expr, 
partition_description descr, 
table_rows 
from information_schema.partitions where 
table_schema = schema() 
and table_name='trb3';
+------+------+-------+------------+
| part | expr | descr | table_rows |
+------+------+-------+------------+
| p0 | `id` | NULL | 7472 |
| p1 | `id` | NULL | 0 |
| p2 | `id` | NULL | 0 |
| p3 | `id` | NULL | 0 |
+------+------+-------+------------+
4 rows in set (0.00 sec)
mysql> select 1826*4;
+--------+
| 1826*4 |
+--------+
| 7304 |
+--------+
1 row in set (0.00 sec)</pre>
<p>count(*)行数一致，说明数据没出问题，但是information_schema.partitions查出来的不对<del>，这就不知道为什么了</del></p>
<blockquote>
<p>For partitioned InnoDB tables, the row count given in the TABLE_ROWS column of the INFORMATION_SCHEMA.PARTITIONS table is only an estimated value used in SQL optimization, and is not always exact.</p>
</blockquote>
<pre class="brush:sql;">mysql> select count(*) from trb3;
+----------+
| count(*) |
+----------+
| 7304 |
+----------+
但是count(*)还是7304，什么鬼</pre>
<p>再次改变分区方案</p>
<pre class="brush:sql;">ALTER TABLE trb3 
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)
);
mysql> select 
-> partition_name part, 
-> partition_expression expr, 
-> partition_description descr, 
-> table_rows 
-> from information_schema.partitions where 
-> table_schema = schema() 
-> and table_name='trb3';
+------+------------------+-------+------------+
| part | expr | descr | table_rows |
+------+------------------+-------+------------+
| p0 | YEAR(purchased) | 1990 | 1826 |
| p1 | YEAR(purchased) | 1995 | 1826 |
| p2 | YEAR(purchased) | 2000 | 0 |
| p3 | YEAR(purchased) | 2005 | 0 |
+------+------------------+-------+------------+
4 rows in set (0.00 sec)</pre>
<p><del>丢数据了。。</del><br>
更正，实际没丢，这个information_shcema.partitions表有延迟，过一会再查就好了</p>
<pre class="brush:sql;">mysql> select 
-> partition_name part, 
-> partition_expression expr, 
-> partition_description descr, 
-> table_rows 
-> from information_schema.partitions where 
-> table_schema = schema() 
-> and table_name='trb3';
+------+------------------+-------+------------+
| part | expr | descr | table_rows |
+------+------------------+-------+------------+
| p0 | YEAR(purchased) | 1990 | 1826 |
| p1 | YEAR(purchased) | 1995 | 1826 |
| p2 | YEAR(purchased) | 2000 | 1826 |
| p3 | YEAR(purchased) | 2005 | 1826 |
+------+------------------+-------+------------+
4 rows in set (0.00 sec)</pre>
<p>官方文档说：<br>
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;<br>
就是说ALTER TABLE trb3 PARTITION BY与 drop table然后重新create table trb3 partition by key(id) partitions 2一样呢。</p>
<h3 id="改存储引擎和普通表没啥区别">改存储引擎，和普通表没啥区别</h3>
<pre class="brush:sql;">mysql> drop table trb3;
Query OK, 0 rows affected (0.01 sec)
mysql> 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)
-> );
Query OK, 0 rows affected (0.03 sec)
mysql> call pr_trb3('1985-01-01','2004-12-31','trb3');
Query OK, 0 rows affected (1.69 sec)
mysql> select 
-> partition_name part, 
-> partition_expression expr, 
-> partition_description descr, 
-> table_rows 
-> from information_schema.partitions where 
-> table_schema = schema() 
-> and table_name='trb3';
+------+------------------+-------+------------+
| part | expr | descr | table_rows |
+------+------------------+-------+------------+
| p0 | YEAR(purchased) | 1990 | 1826 |
| p1 | YEAR(purchased) | 1995 | 1826 |
| p2 | YEAR(purchased) | 2000 | 1826 |
| p3 | YEAR(purchased) | 2005 | 1826 |
+------+------------------+-------+------------+
4 rows in set (0.01 sec)
mysql> alter table trb3 engine=myisam;
Query OK, 7304 rows affected (0.02 sec)
Records: 7304 Duplicates: 0 Warnings: 0
mysql> select 
-> partition_name part, 
-> partition_expression expr, 
-> partition_description descr, 
-> table_rows 
-> from information_schema.partitions where 
-> table_schema = schema() 
-> and table_name='trb3';
+------+------------------+-------+------------+
| part | expr | descr | table_rows |
+------+------------------+-------+------------+
| p0 | YEAR(purchased) | 1990 | 1826 |
| p1 | YEAR(purchased) | 1995 | 1826 |
| p2 | YEAR(purchased) | 2000 | 1826 |
| p3 | YEAR(purchased) | 2005 | 1826 |
+------+------------------+-------+------------+
4 rows in set (0.01 sec)
mysql> show create table trb3\G
*************************** 1. row ***************************
Table: trb3
Create Table: CREATE TABLE `trb3` (
`id` int(11) DEFAULT NULL,
`name` varchar(50) DEFAULT NULL,
`purchased` date DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=utf8
/*!50100 PARTITION BY RANGE ( YEAR(purchased))
(PARTITION p0 VALUES LESS THAN (1990) ENGINE = MyISAM,
PARTITION p1 VALUES LESS THAN (1995) ENGINE = MyISAM,
PARTITION p2 VALUES LESS THAN (2000) ENGINE = MyISAM,
PARTITION p3 VALUES LESS THAN (2005) ENGINE = MyISAM) */
1 row in set (0.00 sec)</pre>
<h3 id="将表由分区表改为非分区表">将表由分区表改为非分区表</h3>
<pre class="brush:sql;">mysql> alter table trb3 remove partitioning;
Query OK, 7304 rows affected (0.01 sec)
Records: 7304 Duplicates: 0 Warnings: 0
mysql> select 
-> partition_name part, 
-> partition_expression expr, 
-> partition_description descr, 
-> table_rows 
-> from information_schema.partitions where 
-> table_schema = schema() 
-> and table_name='trb3';
+------+------+-------+------------+
| part | expr | descr | table_rows |
+------+------+-------+------------+
| NULL | NULL | NULL | 7304 |
+------+------+-------+------------+
1 row in set (0.00 sec)
mysql> show create table trb3\G
*************************** 1. row ***************************
Table: trb3
Create Table: CREATE TABLE `trb3` (
`id` int(11) DEFAULT NULL,
`name` varchar(50) DEFAULT NULL,
`purchased` date DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=utf8
1 row in set (0.00 sec)</pre>
<h3 id="range-list分区管理">Range List分区管理</h3>
<pre class="brush:sql;">mysql> drop table trb3;
Query OK, 0 rows affected (0.01 sec)
mysql> 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)
-> );
Query OK, 0 rows affected (0.03 sec)
mysql> call pr_trb3('1985-01-01','2004-12-31','trb3');
Query OK, 0 rows affected (1.75 sec)
mysql> select 
-> partition_name part, 
-> partition_expression expr, 
-> partition_description descr, 
-> table_rows 
-> from information_schema.partitions where 
-> table_schema = schema() 
-> and table_name='trb3';
+------+------------------+-------+------------+
| part | expr | descr | table_rows |
+------+------------------+-------+------------+
| p0 | YEAR(purchased) | 1990 | 1826 |
| p1 | YEAR(purchased) | 1995 | 1826 |
| p2 | YEAR(purchased) | 2000 | 1826 |
| p3 | YEAR(purchased) | 2005 | 1826 |
+------+------------------+-------+------------+
4 rows in set (0.00 sec)</pre>
<h4 id="增加分区">增加分区</h4>
<pre class="brush:sql;">mysql> alter table trb3 add partition (partition p5 values less than(2010));
Query OK, 0 rows affected (0.00 sec)
Records: 0 Duplicates: 0 Warnings: 0</pre>
<h4 id="合并分区">合并分区</h4>
<pre class="brush:sql;">mysql> alter table trb3 reorganize partition p3,p5 into(partition p5 values less than(2010));
Query OK, 1826 rows affected (0.03 sec)
Records: 1826 Duplicates: 0 Warnings: 0
mysql> select 
-> partition_name part, 
-> partition_expression expr, 
-> partition_description descr, 
-> table_rows 
-> from information_schema.partitions where 
-> table_schema = schema() 
-> and table_name='trb3';
+------+------------------+-------+------------+
| part | expr | descr | table_rows |
+------+------------------+-------+------------+
| p0 | YEAR(purchased) | 1990 | 1826 |
| p1 | YEAR(purchased) | 1995 | 1826 |
| p2 | YEAR(purchased) | 2000 | 1826 |
| p5 | YEAR(purchased) | 2010 | 1826 |
+------+------------------+-------+------------+
4 rows in set (0.00 sec)</pre>
<h4 id="分裂分区">分裂分区</h4>
<pre class="brush:sql;">mysql> ALTER TABLE trb3 REORGANIZE PARTITION p5 INTO (
-> PARTITION p3 VALUES LESS THAN (2005),
-> PARTITION p4 VALUES LESS THAN (2010)
-> );
Query OK, 1826 rows affected (0.04 sec)
Records: 1826 Duplicates: 0 Warnings: 0
select 
partition_name part, 
partition_expression expr, 
partition_description descr, 
table_rows 
from information_schema.partitions where 
table_schema = schema() 
and table_name='trb3';
+------+------------------+-------+------------+
| part | expr | descr | table_rows |
+------+------------------+-------+------------+
| p0 | YEAR(purchased) | 1990 | 1826 |
| p1 | YEAR(purchased) | 1995 | 1826 |
| p2 | YEAR(purchased) | 2000 | 1826 |
| p3 | YEAR(purchased) | 2005 | 1826 |
| p4 | YEAR(purchased) | 2010 | 0 |
+------+------------------+-------+------------+
5 rows in set (0.00 sec)</pre>
<h3 id="hash-key分区">HASH KEY分区</h3>
<pre class="brush:sql;">CREATE TABLE trb3 (id INT, name VARCHAR(50), purchased DATE)
PARTITION BY hash( YEAR(purchased) ) 
partitions 12;
mysql>call pr_trb3('1985-01-01','2004-12-31','trb3');
select 
partition_name part, 
partition_expression expr, 
partition_description descr, 
table_rows 
from information_schema.partitions where 
table_schema = schema() 
and table_name='trb3';
+------+------------------+-------+------------+
| part | expr | descr | table_rows |
+------+------------------+-------+------------+
| p0 | YEAR(purchased) | NULL | 731 |
| p1 | YEAR(purchased) | NULL | 365 |
| p2 | YEAR(purchased) | NULL | 365 |
| p3 | YEAR(purchased) | NULL | 365 |
| p4 | YEAR(purchased) | NULL | 366 |
| p5 | YEAR(purchased) | NULL | 730 |
| p6 | YEAR(purchased) | NULL | 730 |
| p7 | YEAR(purchased) | NULL | 730 |
| p8 | YEAR(purchased) | NULL | 732 |
| p9 | YEAR(purchased) | NULL | 730 |
| p10 | YEAR(purchased) | NULL | 730 |
| p11 | YEAR(purchased) | NULL | 730 |
+------+------------------+-------+------------+
12 rows in set (0.00 sec)</pre>
<h4 id="缩建分区从12个到8个">缩建分区从12个到8个</h4>
<pre class="brush:sql;">mysql> ALTER TABLE trb3 COALESCE PARTITION 4;
Query OK, 7304 rows affected (0.13 sec)
Records: 7304 Duplicates: 0 Warnings: 0
select 
partition_name part, 
partition_expression expr, 
partition_description descr, 
table_rows 
from information_schema.partitions where 
table_schema = schema() 
and table_name='trb3';
+------+------------------+-------+------------+
| part | expr | descr | table_rows |
+------+------------------+-------+------------+
| p0 | YEAR(purchased) | NULL | 732 |
| p1 | YEAR(purchased) | NULL | 1095 |
| p2 | YEAR(purchased) | NULL | 1095 |
| p3 | YEAR(purchased) | NULL | 1095 |
| p4 | YEAR(purchased) | NULL | 1097 |
| p5 | YEAR(purchased) | NULL | 730 |
| p6 | YEAR(purchased) | NULL | 730 |
| p7 | YEAR(purchased) | NULL | 730 |
+------+------------------+-------+------------+
8 rows in set (0.00 sec)
mysql> select count(*) from trb3;
+----------+
| count(*) |
+----------+
| 7304 |
+----------+
1 row in set (0.00 sec)</pre>
<p>没丢数据</p>
<p>收缩前2004年在P0</p>
<pre class="brush:sql;">mysql> select mod(2004,12);
+--------------+
| mod(2004,12) |
+--------------+
| 0 |
+--------------+</pre>
<p>收缩后2004年在P4</p>
<pre class="brush:sql;">mysql> select mod(2004,8);
+-------------+
| mod(2004,8) |
+-------------+
| 4 |
+-------------+</pre>
<h3 id="exchanging-partitions-and-subpartitions-with-tables">Exchanging Partitions and Subpartitions with Tables</h3>
<h3 id="分区子分区交换">分区(子分区)交换</h3>
<pre class="brush:sql;"> ALTER TABLE pt EXCHANGE PARTITION p WITH TABLE nt</pre>
<p>pt是一个分区表，p是pt的分区或子分区，而nt是一个非分区表</p>
<h4 id="限制条件">限制条件:</h4>
<p>1.表nt不是分区表<br>
2.表nt不是临时表<br>
3.表pt和nt结构在其他方面是相同的<br>
4.表n没有外键约束，也没有其他表引用它的列为外键<br>
5.表nt的所有行都包含在表p的分区范围内(比如p range分区最大values less than 10，那么表nt不能有大于等于10的值)</p>
<h4 id="权限">权限:</h4>
<p>除了 ALTER, INSERT, and CREATE 权限外，你还要有DROP权限才能执行ALTER TABLE … EXCHANGE PARTITION.</p>
<h4 id="其他注意事项">其他注意事项:</h4>
<p>1.执行ALTER TABLE … EXCHANGE PARTITION 不会调用任何在nt表和p表上的触发器<br>
2.在交换表中的任何AUTO_INCREMENT列会被reset<br>
3.IGNORE关键字在执行ALTER TABLE … EXCHANGE PARTITION时会失效</p>
<h4 id="完整实例语句如下">完整实例语句如下:</h4>
<pre class="brush:sql;">ALTER TABLE pt 
EXCHANGE PARTITION p 
WITH TABLE nt;</pre>
<p>在一次ALTER TABLE EXCHANGE PARTITION 中，只能有一个分区和一个非分区表被交换<br>
想交换多个，就执行多次ALTER TABLE EXCHANGE PARTITION<br>
任何MySQL支持的分区类型都可以进行交换</p>
<h4 id="交换实例">交换实例</h4>
<pre class="brush:sql;">CREATE TABLE e (
id INT NOT NULL,
fname VARCHAR(30),
lname VARCHAR(30)
)
PARTITION BY RANGE (id) (
PARTITION p0 VALUES LESS THAN (50),
PARTITION p1 VALUES LESS THAN (100),
PARTITION p2 VALUES LESS THAN (150),
PARTITION p3 VALUES LESS THAN (MAXVALUE)
);
INSERT INTO e VALUES 
(1669, "Jim", "Smith"),
(337, "Mary", "Jones"),
(16, "Frank", "White"),
(2005, "Linda", "Black");</pre>
<p>创建一个与e结构一样的非分区表e2</p>
<pre class="brush:sql;">mysql> create table e2 like e;
Query OK, 0 rows affected (0.01 sec)
mysql> show create table e2\G
*************************** 1. row ***************************
Table: e2
Create Table: CREATE TABLE `e2` (
`id` int(11) NOT NULL,
`fname` varchar(30) DEFAULT NULL,
`lname` varchar(30) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8
/*!50100 PARTITION BY RANGE (id)
(PARTITION p0 VALUES LESS THAN (50) ENGINE = InnoDB,
PARTITION p1 VALUES LESS THAN (100) ENGINE = InnoDB,
PARTITION p2 VALUES LESS THAN (150) ENGINE = InnoDB,
PARTITION p3 VALUES LESS THAN MAXVALUE ENGINE = InnoDB) */
1 row in set (0.00 sec)
mysql> alter table e2 remove partitioning;
Query OK, 0 rows affected (0.02 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> show create table e2\G
*************************** 1. row ***************************
Table: e2
Create Table: CREATE TABLE `e2` (
`id` int(11) NOT NULL,
`fname` varchar(30) DEFAULT NULL,
`lname` varchar(30) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)</pre>
<p>查看数据在e表中的分布:</p>
<pre class="brush:sql;">select 
partition_name part, 
partition_expression expr, 
partition_description descr, 
table_rows 
from information_schema.partitions where 
table_schema = schema() 
and table_name='e'
+------+------+----------+------------+
| part | expr | descr | table_rows |
+------+------+----------+------------+
| p0 | id | 50 | 1 |
| p1 | id | 100 | 0 |
| p2 | id | 150 | 0 |
| p3 | id | MAXVALUE | 3 |
+------+------+----------+------------+
4 rows in set (0.00 sec)</pre>
<p>将分区p0与e2表进行交换:</p>
<pre class="brush:sql;">mysql> ALTER TABLE e EXCHANGE PARTITION p0 WITH TABLE e2;
Query OK, 0 rows affected (0.01 sec)
select 
partition_name part, 
partition_expression expr, 
partition_description descr, 
table_rows 
from information_schema.partitions where 
table_schema = schema() 
and table_name='e';
+------+------+----------+------------+
| part | expr | descr | table_rows |
+------+------+----------+------------+
| p0 | id | 50 | 0 |
| p1 | id | 100 | 0 |
| p2 | id | 150 | 0 |
| p3 | id | MAXVALUE | 3 |
+------+------+----------+------------+
4 rows in set (0.01 sec)
mysql> select * from e2;
+----+-------+-------+
| id | fname | lname |
+----+-------+-------+
| 16 | Frank | White |
+----+-------+-------+
1 row in set (0.00 sec) </pre>
<p>重做实验，这次在交换前在表e2中插入一些数据</p>
<pre class="brush:sql;">mysql> insert into e2 values(16,'FAN','BOSHI');
Query OK, 1 row affected (0.00 sec)
mysql> insert into e2 values(51,'DU','YALAN');
Query OK, 1 row affected (0.00 sec)
mysql> select * from e2;
+----+-------+-------+
| id | fname | lname |
+----+-------+-------+
| 16 | FAN | BOSHI |
| 51 | DU | YALAN |
+----+-------+-------+
2 rows in set (0.00 sec)
mysql> ALTER TABLE e EXCHANGE PARTITION p0 WITH TABLE e2;
ERROR 1737 (HY000): Found a row that does not match the partition</pre>
<p>报错了，因为51超出了p0的范围。<br>
如之前所说，此时使用IGNORE也无济于事</p>
<pre class="brush:sql;">mysql> ALTER IGNORE TABLE e EXCHANGE PARTITION p0 WITH TABLE e2;
ERROR 1737 (HY000): Found a row that does not match the partition</pre>
<p>修改id为49，这样就属于p0的范围了</p>
<pre class="brush:sql;">mysql> update e2 set id=49 where id=51;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> ALTER TABLE e EXCHANGE PARTITION p0 WITH TABLE e2;
Query OK, 0 rows affected (0.01 sec)
mysql> select 
-> partition_name part, 
-> partition_expression expr, 
-> partition_description descr, 
-> table_rows 
-> from information_schema.partitions where 
-> table_schema = schema() 
-> and table_name='e';
+------+------+----------+------------+
| part | expr | descr | table_rows |
+------+------+----------+------------+
| p0 | id | 50 | 2 |
| p1 | id | 100 | 0 |
| p2 | id | 150 | 0 |
| p3 | id | MAXVALUE | 3 |
+------+------+----------+------------+
4 rows in set (0.00 sec)
e2的数据被交换到了p0中
mysql> select * from e partition(p0);
+----+-------+-------+
| id | fname | lname |
+----+-------+-------+
| 16 | FAN | BOSHI |
| 49 | DU | YALAN |
+----+-------+-------+
2 rows in set (0.00 sec)
e的p0分区中的数据被交换到了e2中
mysql> select * from e2;
+----+-------+-------+
| id | fname | lname |
+----+-------+-------+
| 16 | Frank | White |
+----+-------+-------+
1 row in set (0.01 sec)</pre>
<h4 id="交换subpartition">交换subpartition</h4>
<pre class="brush:sql;">CREATE TABLE es (
id INT NOT NULL,
fname VARCHAR(30),
lname VARCHAR(30)
)
PARTITION BY RANGE (id)
SUBPARTITION BY KEY (lname)
SUBPARTITIONS 2 (
PARTITION p0 VALUES LESS THAN (50),
PARTITION p1 VALUES LESS THAN (100),
PARTITION p2 VALUES LESS THAN (150),
PARTITION p3 VALUES LESS THAN (MAXVALUE)
);
INSERT INTO es VALUES
(1669, "Jim", "Smith"),
(337, "Mary", "Jones"),
(16, "Frank", "White"),
(2005, "Linda", "Black");
CREATE TABLE es2 LIKE es;
ALTER TABLE es2 REMOVE PARTITIONING;</pre>
<p>尽管我们没有显示的指定每个子分区的名字，我们仍可以通过information_schema.partitions表获取到子分区的名字</p>
<pre class="brush:sql;">select 
partition_name part, 
subpartition_name, 
partition_expression expr, 
partition_description descr, 
table_rows 
from information_schema.partitions where 
table_schema = schema() 
and table_name='es';
+------+-------------------+------+----------+------------+
| part | subpartition_name | expr | descr | table_rows |
+------+-------------------+------+----------+------------+
| p0 | p0sp0 | id | 50 | 1 |
| p0 | p0sp1 | id | 50 | 0 |
| p1 | p1sp0 | id | 100 | 0 |
| p1 | p1sp1 | id | 100 | 0 |
| p2 | p2sp0 | id | 150 | 0 |
| p2 | p2sp1 | id | 150 | 0 |
| p3 | p3sp0 | id | MAXVALUE | 3 |
| p3 | p3sp1 | id | MAXVALUE | 0 |
+------+-------------------+------+----------+------------+</pre>
<p>接下来，开始将p3sp0和es进行交换</p>
<pre class="brush:sql;">mysql> select * from es partition(p3sp0);
+------+-------+-------+
| id | fname | lname |
+------+-------+-------+
| 1669 | Jim | Smith |
| 337 | Mary | Jones |
| 2005 | Linda | Black |
+------+-------+-------+
3 rows in set (0.00 sec)
mysql> ALTER TABLE es EXCHANGE PARTITION p3sp0 WITH TABLE es2;
Query OK, 0 rows affected (0.00 sec)
mysql> select * from es partition(p3sp0);
Empty set (0.00 sec)
mysql> select * from es2;
+------+-------+-------+
| id | fname | lname |
+------+-------+-------+
| 1669 | Jim | Smith |
| 337 | Mary | Jones |
| 2005 | Linda | Black |
+------+-------+-------+
3 rows in set (0.00 sec)</pre>
<p>如果一个分区表有子分区，那么你只能以子分区为粒度进行交换，而不能直接交换子分区的父分区</p>
<pre class="brush:sql;">mysql> ALTER TABLE es EXCHANGE PARTITION p3 WITH TABLE es2;
ERROR 1704 (HY000): Subpartitioned table, use subpartition instead of partition</pre>
<p>EXCHANGE PARTITION有着严格的要求<br>
两个将要交换的表的 列名，列的创建顺序，列的数量，以及索引都要严格一致。当然存储引擎也要一致</p>
<pre class="brush:sql;">mysql> desc es2;
+-------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| id | int(11) | NO | | NULL | |
| fname | varchar(30) | YES | | NULL | |
| lname | varchar(30) | YES | | NULL | |
+-------+-------------+------+-----+---------+-------+
3 rows in set (0.00 sec)
mysql> create index id_name on es2(id,fname);
Query OK, 0 rows affected (0.01 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> ALTER TABLE es EXCHANGE PARTITION p3sp0 WITH TABLE es2;
ERROR 1736 (HY000): Tables have different definitions</pre>
<p>改变es2的存储引擎</p>
<pre class="brush:sql;">mysql> drop index id_name on es2;
Query OK, 0 rows affected (0.00 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> alter table es2 engine=myisam;
Query OK, 0 rows affected (0.01 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> ALTER TABLE es EXCHANGE PARTITION p3sp0 WITH TABLE es2;
ERROR 1497 (HY000): The mix of handlers in the partitions is not allowed in this version of MySQL</pre>
<h3 id="分区表的维护">分区表的维护</h3>
<p>CHECK TABLE, OPTIMIZE TABLE, ANALYZE TABLE, and REPAIR TABLE可以被用于维护分区表</p>
<p>Rebuilding partitions.相当于将分区中的数据drop掉再插入回来,对于避免磁盘碎片很有效<br>
Example:</p>
<pre class="brush:sql;">ALTER TABLE t1 REBUILD PARTITION p0, p1;</pre>
<p>Optimizing partitions.如果你的表增加删除了大量数据，或者进行了大量的边长列的更新操作( VARCHAR, BLOB, or TEXT columns)。那么optimize partition将回收未使用的空间，并整理分区数据文件。<br>
Example:</p>
<pre class="brush:sql;">ALTER TABLE t1 OPTIMIZE PARTITION p0, p1;</pre>
<p>运行OPTIMIZE PARTITION 相当于做了 CHECK PARTITION, ANALYZE PARTITION, and REPAIR PARTITION</p>
<blockquote>
<p>Some MySQL storage engines, including InnoDB, do not support per-partition optimization; in these cases, ALTER TABLE … OPTIMIZE PARTITION rebuilds the entire table. In MySQL 5.6.9 and later, running this statement on such a table causes the entire table to rebuilt and analyzed, and an appropriate warning to be issued. (Bug #11751825, Bug #42822) Use ALTER TABLE … REBUILD PARTITION and ALTER TABLE … ANALYZE PARTITION instead, to avoid this issue.</p>
</blockquote>
<p>Analyzing partitions.读取并保存分区的键分布<br>
Example:</p>
<pre class="brush:sql;">ALTER TABLE t1 ANALYZE PARTITION p3;</pre>
<p>Repairing partitions.修补被破坏的分区<br>
Example:</p>
<pre class="brush:sql;">ALTER TABLE t1 REPAIR PARTITION p0,p1;</pre>
<p>Checking partitions.可以使用几乎与对非分区表使用CHECK TABLE 相同的方式检查分区。<br>
Example:</p>
<pre class="brush:sql;">ALTER TABLE trb3 CHECK PARTITION p1;</pre>
<p>这个命令可以告诉你表trb3的分区p1中的数据或索引是否已经被破坏。如果发生了这种情况，使用“ALTER TABLE … REPAIR PARTITION”来修补该分区。</p>
<h4 id="以上每个命令都支持将分区换成all">以上每个命令都支持将分区换成ALL</h4>
<blockquote>
<p>The use of mysqlcheck and myisamchk is not supported with partitioned tables.</p>
</blockquote>
<p>mysqlcheck和myisamchk不支持分区表</p>
<p>你可以使用 ALTER TABLE … TRUNCATE PARTITION. 来删除一个或多个分区中的数据<br>
如:ALTER TABLE … TRUNCATE PARTITION ALL删除所有数据</p>
<p>ANALYZE, CHECK, OPTIMIZE, REBUILD, REPAIR, and TRUNCATE 操作不支持 subpartitions.</p>
</enddate>

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