innodb_log_file_size设置

innodb_log_file_size的大小设置将会影响MySQL数据库的写入性能，若设置的太小，
会增加checkpoint写的次数，以下测试在MySQL5.7版本中的如何修改innodb_log_file_size


[root@endb local]# mysql
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.9-log MySQL Community Server (GPL)


Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.


Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.


Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.


mysql> show variables like '%innodb_log_file%';
+---------------------------+------------+
| Variable_name             | Value      |
+---------------------------+------------+
| innodb_log_file_size      | 1073741824 |
| innodb_log_files_in_group | 2          |
+---------------------------+------------+
2 rows in set (0.00 sec)


mysql> select 1073741824/1024/1024;
+----------------------+
| 1073741824/1024/1024 |
+----------------------+
|        1024.00000000 |
+----------------------+
1 row in set (0.00 sec)




这里确认innodb_fast_shutdown为1，这样在重启MySQL时，不会使用ib_logfile文件
mysql> show variables like '%shutdown%';
+-------------------------------------+-------+
| Variable_name                       | Value |
+-------------------------------------+-------+
| innodb_buffer_pool_dump_at_shutdown | ON    |
| innodb_fast_shutdown                | 1     |
+-------------------------------------+-------+
2 rows in set (0.00 sec)




mysql> show variables like '%datadir%';
+---------------+--------------+
| Variable_name | Value        |
+---------------+--------------+
| datadir       | /home/mysql/ |
+---------------+--------------+
1 row in set (0.00 sec)


[root@endb local]# /etc/init.d/mysql stop
Shutting down MySQL...[  OK  ]
[root@endb local]# grep innodb_log /etc/my.cnf 
innodb_log_file_size = 512M


[root@endb mysql]# cp ib_logfile* ..
[root@endb mysql]# ll ib_logfile*
-rw-r----- 1 mysql mysql 1073741824 Mar  3 15:03 ib_logfile0
-rw-r----- 1 mysql mysql 1073741824 Nov 25 16:09 ib_logfile1
[root@endb mysql]# ll -h ib_logfile*
-rw-r----- 1 mysql mysql 1.0G Mar  3 15:03 ib_logfile0
-rw-r----- 1 mysql mysql 1.0G Nov 25 16:09 ib_logfile1


mysql> show variables like '%innodb_log%';
+-----------------------------+-----------+
| Variable_name               | Value     |
+-----------------------------+-----------+
| innodb_log_buffer_size      | 16777216  |
| innodb_log_checksums        | ON        |
| innodb_log_compressed_pages | ON        |
| innodb_log_file_size        | 536870912 |
| innodb_log_files_in_group   | 2         |
| innodb_log_group_home_dir   | ./        |
| innodb_log_write_ahead_size | 8192      |
+-----------------------------+-----------+
7 rows in set (0.00 sec)
[root@endb mysql]# ll -h ib_logfile*
-rw-r----- 1 mysql mysql 512M Mar  3 15:05 ib_logfile0
-rw-r----- 1 mysql mysql 512M Mar  3 15:05 ib_logfile1

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