MySQL如何設置innodb_log_file_size

1.查看pmm的“InnoDB Log File Usage Hourly”

2.查看pmm的“Inodb checkpoint age”

如果Uncheckpointed Bytes非常接近Max Checkpoint Age，就可以確定當前的innodb_log_file_size影響了性能。

3.在業務高峰期估算：

mysql> pager grep sequence
PAGER set to 'grep sequence'
mysql> show engine innodb statusG select sleep(60); show engine innodb statusG
Log sequence number 84 3836410803
1 row in set (0.06 sec)
​
1 row in set (1 min 0.00 sec)
​
Log sequence number 84 3838334638
1 row in set (0.05 sec)
mysql> select (3838334638 - 3836410803) / 1024 / 1024 as MB_per_min;
+------------+
| MB_per_min |
+------------+
| 1.83471203 | 
+------------+

這里估算出來的是每分鍾生成量，每小時大概是118MB，設置成2的倍數是128MB，因為有兩組redo日志。所以設置成：

innodb_log_file_size=64M

4.業務高峰期執行估算：

mysql> show global status like 'Innodb_os_log_written';select sleep(60); show global status like 'Innodb_os_log_written';

原理和方法3類似。