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MySQL的LIST分区体验与总结

王朝mysql·作者佚名  2008-05-21
窄屏简体版  字體: |||超大  

终于有点空闲时间了,测试一下LIST分区,因为LIST在我们的开发中用到。他分区以后再补上。

版本:

Server version: 5.1.23a-maria-alpha-log MySQL Community Server [Maria] (GPL)

一、讲在前面

注意:

1、ALTER TABLE也可以用于对带分区的表进行重新分区,所以不能在建表之后再用ALTER TABLE语法。

2、如果你表中有KEY。用来分区的字段必须是KEY的一部份。

3、现在的分区属于水平分区。(垂直分区我们可以自己模拟,这个以后再写)

mysql> use t_girl

Database changed

先建立一个普通表

mysql> create table category( cid int unsigned not null auto_increment primary key, cname varchar(64) not null, parent_id int not null);

Query OK, 0 rows affected (0.00 sec)

mysql> create table parent(parent_id int not null auto_increment primary key,pname varchar(64) not null);

Query OK, 0 rows affected (0.00 sec)

分区表

mysql> create table category_part( cid int unsigned not null auto_increment,cname varchar(64) not null,parent_id int not null,primary key (cid,parent_id))

partition by list(parent_id)(

partition p1 values in (1,2,3,6,9),

partition p2 values in (4,5,10,22,23),

partition p3 values in (7,8,11,12,13),

partition p4 values in (14,15,16,17,20),

partition p5 values in (18,19,21,24,25)

);

Query OK, 0 rows affected (0.01 sec)

插入数据部分省略。。。

建立索引。

mysql> create index f_parent_id on category(parent_id);

Query OK, 2048000 rows affected (17.61 sec)

Records: 2048000 Duplicates: 0 Warnings: 0

mysql> show index from category;

+----------+------------+-------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+

| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment |

+----------+------------+-------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+

| category | 0 | PRIMARY | 1 | cid | A | 2048000 | NULL | NULL | | BTREE | |

| category | 1 | f_parent_id | 1 | parent_id | A | 25 | NULL | NULL | | BTREE | |

+----------+------------+-------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+

2 rows in set (0.00 sec)

mysql> create index f_parent_id on category_part(parent_id);

Query OK, 2048000 rows affected (18.57 sec)

Records: 2048000 Duplicates: 0 Warnings: 0

mysql> show index from category_part;

+---------------+------------+-------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+

| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment |

+---------------+------------+-------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+

| category_part | 0 | PRIMARY | 1 | cid | A | 2048000 | NULL | NULL | | BTREE | |

| category_part | 0 | PRIMARY | 2 | parent_id | A | 2048000 | NULL | NULL | | BTREE | |

| category_part | 1 | f_parent_id | 1 | parent_id | A | 318 | NULL | NULL | | BTREE | |

+---------------+------------+-------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+

3 rows in set (0.01 sec)

mysql> select count(*) from category;

+----------+

| count(*) |

+----------+

| 2048000 |

+----------+

1 row in set (0.00 sec)

mysql> select count(*) from category_part;

+----------+

| count(*) |

+----------+

| 2048000 |

+----------+

1 row in set (0.00 sec)

mysql> select count(*) from parent;

+----------+

| count(*) |

+----------+

| 25 |

+----------+

1 row in set (0.00 sec)

二、具体测试

1、我们来看一下查询性能比较:

1)、单表查询

mysql> select count(*) from category where parent_id in (22,20);

+----------+

| count(*) |

+----------+

| 17002 |

+----------+

1 row in set (0.03 sec)

mysql> select count(*) from category_part where parent_id in (22,20);

+----------+

| count(*) |

+----------+

| 17002 |

+----------+

1 row in set (0.02 sec)

分区表普通的做了索引的速度上快了一点,不过差别不是很大。

mysql> explain select count(*) from category where parent_id in (22,20);

+----+-------------+----------+-------+---------------+-------------+---------+------+-------+--------------------------+

| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |

+----+-------------+----------+-------+---------------+-------------+---------+------+-------+--------------------------+

| 1 | SIMPLE | category | range | f_parent_id | f_parent_id | 4 | NULL | 14335 | Using where; Using index |

+----+-------------+----------+-------+---------------+-------------+---------+------+-------+--------------------------+

1 row in set (0.00 sec)

mysql> explain partitions select count(*) from category_part where parent_id in (22,20);

+----+-------------+---------------+------------+-------+---------------+-------------+---------+------+-------+--------------------------+

| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | Extra |

+----+-------------+---------------+------------+-------+---------------+-------------+---------+------+-------+--------------------------+

| 1 | SIMPLE | category_part | p2,p4 | range | f_parent_id | f_parent_id | 4 | NULL | 16893 | Using where; Using index |

+----+-------------+---------------+------------+-------+---------------+-------------+---------+------+-------+--------------------------+

1 row in set (0.00 sec)

mysql> select count(*) from category where parent_id = 25;

+----------+

| count(*) |

+----------+

| 2001 |

+----------+

1 row in set (0.01 sec)

mysql> select count(*) from category_part where parent_id = 25;

+----------+

| count(*) |

+----------+

| 2001 |

+----------+

1 row in set (0.00 sec)

mysql> explain select count(*) from category where parent_id = 25;

+----+-------------+----------+------+---------------+-------------+---------+-------+-------+-------------+

| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |

+----+-------------+----------+------+---------------+-------------+---------+-------+-------+-------------+

| 1 | SIMPLE | category | ref | f_parent_id | f_parent_id | 4 | const | 38240 | Using index |

+----+-------------+----------+------+---------------+-------------+---------+-------+-------+-------------+

1 row in set (0.00 sec)

mysql> explain partitions select count(*) from category_part where parent_id = 25;

+----+-------------+---------------+------------+------+---------------+-------------+---------+-------+------+-------------+

| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | Extra |

+----+-------------+---------------+------------+------+---------------+-------------+---------+-------+------+-------------+

| 1 | SIMPLE | category_part | p5 | ref | f_parent_id | f_parent_id | 4 | const | 4647 | Using index |

+----+-------------+---------------+------------+------+---------------+-------------+---------+-------+------+-------------+

1 row in set (0.00 sec)

可以看出,扫描的行数大幅度减少

2)、多表内联性能

mysql> select count(*) from category as a inner join parent as b using(parent_id);

+----------+

| count(*) |

+----------+

| 2048000 |

+----------+

1 row in set (0.84 sec)

mysql> select count(*) from category_part as a inner join parent as b using(parent_id);

+----------+

| count(*) |

+----------+

| 2048000 |

+----------+

1 row in set (0.88 sec)

mysql> explain select count(*) from category as a inner join parent as b using(parent_id);

+----+-------------+-------+-------+---------------+-------------+---------+--------------------+-------+-------------+

| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |

+----+-------------+-------+-------+---------------+-------------+---------+--------------------+-------+-------------+

| 1 | SIMPLE | b | index | PRIMARY | PRIMARY | 4 | NULL | 25 | Using index |

| 1 | SIMPLE | a | ref | f_parent_id | f_parent_id | 4 | t_girl.b.parent_id | 81920 | Using index |

+----+-------------+-------+-------+---------------+-------------+---------+--------------------+-------+-------------+

2 rows in set (0.00 sec)

mysql> explain partitions select count(*) from category_part as a inner join parent as b using(parent_id);

+----+-------------+-------+----------------+-------+---------------+-------------+---------+--------------------+------+-------------+

| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | Extra |

+----+-------------+-------+----------------+-------+---------------+-------------+---------+--------------------+------+-------------+

| 1 | SIMPLE | b | NULL | index | PRIMARY | PRIMARY | 4 | NULL | 25 | Using index |

| 1 | SIMPLE | a | p1,p2,p3,p4,p5 | ref | f_parent_id | f_parent_id | 4 | t_girl.b.parent_id | 6421 | Using index |

+----+-------------+-------+----------------+-------+---------------+-------------+---------+--------------------+------+-------------+

2 rows in set (0.00 sec)

可以看出,扫描的行数大幅度减少

mysql> explain select count(*) from category as a inner join parent as b using(parent_id) where a.parent_id =19;

+----+-------------+-------+-------+---------------+-------------+---------+-------+------+-------------+

| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |

+----+-------------+-------+-------+---------------+-------------+---------+-------+------+-------------+

| 1 | SIMPLE | b | const | PRIMARY | PRIMARY | 4 | const | 1 | Using index |

| 1 | SIMPLE | a | ref | f_parent_id | f_parent_id | 4 | const | 6746 | Using index |

+----+-------------+-------+-------+---------------+-------------+---------+-------+------+-------------+

2 rows in set (0.00 sec)

mysql> explain partitions select count(*) from category_part as a inner join parent as b using(parent_id) where a.parent_id =19;

+----+-------------+-------+------------+-------+---------------+-------------+---------+-------+------+-------------+

| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | Extra |

+----+-------------+-------+------------+-------+---------------+-------------+---------+-------+------+-------------+

| 1 | SIMPLE | b | NULL | const | PRIMARY | PRIMARY | 4 | const | 1 | Using index |

| 1 | SIMPLE | a | p5 | ref | f_parent_id | f_parent_id | 4 | const | 5203 | Using index |

+----+-------------+-------+------------+-------+---------------+-------------+---------+-------+------+-------------+

2 rows in set (0.00 sec)

由以上数据可以看出,数据越大,查询性能提升的越明显!

2、下来看看写性能

mysql> insert into category(cname,parent_id) values ('Test',1);

Query OK, 1 row affected (0.01 sec)

mysql> insert into category_part(cname,parent_id) values ('Test',1);

Query OK, 1 row affected (0.00 sec)

mysql> select * from category into outfile '/tmp/a.txt';

ERROR 1086 (HY000): File '/tmp/a.txt' already exists

mysql> select * from category into outfile '/tmp/test.dat';

Query OK, 2048005 rows affected (2.82 sec)

mysql> truncate table category;

Query OK, 0 rows affected (0.06 sec)

mysql> truncate table category_part;

Query OK, 2048005 rows affected (0.10 sec)

mysql> load data infile '/tmp/test.dat' into table category;

Query OK, 2048005 rows affected (17.67 sec)

Records: 2048005 Deleted: 0 Skipped: 0 Warnings: 0

mysql> load data infile '/tmp/test.dat' into table category_part;

Query OK, 2048005 rows affected (21.62 sec)

Records: 2048005 Deleted: 0 Skipped: 0 Warnings: 0

可以看出,写性能损失不了多少。

牺牲了少许写的性能却大幅度提高了查询的性能,这个是值得的。

如果我有什么说的不对的地方,欢迎各位提意见!

 
 
 
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