如何设置mysql innodb 表的压缩
一、 如何设置mysql innodb 表的压缩
设置innodb 表的 压缩
第一，mysql的版本需要大于5.5
第二，设置innodb_file_format=barracuda
第三，create table或者alter talble 增加 ROW_FORMAT=COMPRESSED KEY_BLOCK_SIZE=8;(默认的key_block_size=16)
根据经验，一般压缩比例可以达到30%-40%
顺序不能改变， 先设置字符集给事为 innodb_file_format=barracuda，然后再建表或者修改表的compaesed
二 步骤
---设置innodb字符集set global innodb_file_format=Barracuda
vi /etc/my.cnf 添加
innodb_file_format=Barracuda
--修改表压缩
alter table t row_format=COMPRESSED;
或者建表
create table t(id int,a varchar(10)) ENGINE=InnoDB ROW_FORMAT=COMPRESSED
注意：
在innodb_file_format=antelope的情况下，建立压缩表（表结构中带有row_format=compressed），然后在设置innodb_file_format=barracuda ，此时建立的压缩表会忽略压缩参数
三、实验
3.1 Antelope 字符集下 建立压缩innodb表
mysql> show global variables like 'innodb_file_format%';+--------------------------+----------+
| Variable_name | Value |
+--------------------------+----------+
| innodb_file_format | Antelope |
| innodb_file_format_check | ON |
| innodb_file_format_max | Antelope |
+--------------------------+----------+
3 rows in set (0.02 sec)
mysql> create table t(id int,a varchar(10)) ENGINE=InnoDB ROW_FORMAT=COMPRESSED
-> ;
Query OK, 0 rows affected, 2 warnings (0.24 sec)
mysql> show warnings;
+---------+------+-----------------------------------------------------------------------+
| Level | Code | Message |
+---------+------+-----------------------------------------------------------------------+
| Warning | 1478 | InnoDB: ROW_FORMAT=COMPRESSED requires innodb_file_format > Antelope. |
| Warning | 1478 | InnoDB: assuming ROW_FORMAT=COMPACT. |
+---------+------+-----------------------------------------------------------------------+
2 rows in set (0.00 sec)
查看压缩表的状态
mysql> show table status like 't'\G;
*************************** 1. row ***************************
Name: t
Engine: InnoDB
Version: 10
Row_format: Compact //显示没有压缩
Rows: 0
Avg_row_length: 0
Data_length: 16384
Max_data_length: 0
Index_length: 0
Data_free: 0
Auto_increment: NULL
Create_time: 2017-02-03 17:48:56
Update_time: NULL
Check_time: NULL
Collation: utf8_general_ci
Checksum: NULL
Create_options: row_format=COMPRESSED
Comment:
1 row in set (0.01 sec)
结论：我们也就得出字符集是innodb_file_format=antelope，是不能够压缩的，压缩选项会被忽略掉
3.2 Barracuda 字符集下 建立压缩innodb表
修改字符集：
set global innodb_file_format=Barracuda
mysql> set global innodb_file_format=Barracuda ;
Query OK, 0 rows affected (0.00 sec)
mysql> show global variables like 'innodb_file_format%';
+--------------------------+-----------+
| Variable_name | Value |
+--------------------------+-----------+
| innodb_file_format | Barracuda |
| innodb_file_format_check | ON |
| innodb_file_format_max | Antelope |
+--------------------------+-----------+
3 rows in set (0.00 sec)
mysql> drop table t;
Query OK, 0 rows affected (0.16 sec)
mysql> create table t(id int,a varchar(10)) ENGINE=InnoDB ROW_FORMAT=COMPRESSED ;
Query OK, 0 rows affected (0.27 sec)
mysql> show table status like 't'\G;
*************************** 1. row ***************************
Name: t
Engine: InnoDB
Version: 10
Row_format: Compressed //正确压缩
Rows: 0
Avg_row_length: 0
Data_length: 8192
Max_data_length: 0
Index_length: 0
Data_free: 0
Auto_increment: NULL
Create_time: 2017-02-03 17:53:10
Update_time: NULL
Check_time: NULL
Collation: utf8_general_ci
Checksum: NULL
Create_options: row_format=COMPRESSED
Comment:
1 row in set (0.00 sec)
mysql> show create table t\G
*************************** 1. row ***************************
Table: t
Create Table: CREATE TABLE `t` (
`id` int(11) DEFAULT NULL,
`a` varchar(10) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 ROW_FORMAT=COMPRESSED
1 row in set (0.00 sec)
如果是这种方式不能正确的查看表是否已经压缩
四、注意
mysql> show global variables like '%innodb_file_format%';+--------------------------+-----------+
| Variable_name | Value |
+--------------------------+-----------+
| innodb_file_format | Barracuda |
| innodb_file_format_check | ON |
| innodb_file_format_max | Barracuda |
+--------------------------+-----------+
3 rows in set (0.00 sec)
mysql> exit
Bye
[root@dg mysql]# service mysql restart
Shutting down MySQL.. [确定]
Starting MySQL.. [确定]
mysql> show global variables like '%innodb_file_format%';
+--------------------------+-----------+
| Variable_name | Value |
+--------------------------+-----------+
| innodb_file_format | Antelope |
| innodb_file_format_check | ON |
| innodb_file_format_max | Barracuda |
+--------------------------+-----------+
3 rows in set (0.00 sec)
重启后字符集又变了，所以要在参数文件中标明innodb_file_format= Barracuda ，重启后才不会改变
注意： 我们可以通过命令来修改 innodb_file_format= Barracuda的字符集格式，但是往往我们会忽略掉，或者忘记了参数文件中曾经设置过字符集是 innodb_file_format=Antelope或者参数文件中曾经没有设置过 innodb_file_format，
重启后参数还原成了innodb_file_format=Antelope，而表可能会让我们的压缩重新回到不压缩的状态，所以一定要记住在参数文件中设置字符集
mysql> show global variables like '%innodb_strict_mode%';
+--------------------+-------+
| Variable_name | Value |
+--------------------+-------+
| innodb_strict_mode | OFF |
+--------------------+-------+
1 row in set (0.00 sec)