MySQL InnoDB Redo 与 Undo
redo log重做日志介绍
![321324421 321324421](https://img2020.cnblogs.com/blog/1165731/202009/1165731-20200913164126502-1088607182.png)
![321523671 321523671](https://img2020.cnblogs.com/blog/1165731/202009/1165731-20200913164127373-545432081.png)
redo log重做日志的由来
![321589109 321589109](https://img2020.cnblogs.com/blog/1165731/202009/1165731-20200913164128190-285587735.png)
![321761296 321761296](https://img2020.cnblogs.com/blog/1165731/202009/1165731-20200913164129067-2129547009.png)
如何写 redo log重做日志的呢
![327751984 327751984](https://img2020.cnblogs.com/blog/1165731/202009/1165731-20200913164129810-1116092560.png)
log buffer 往 log file里写 redo log的触发机制
![327846109 327846109](https://img2020.cnblogs.com/blog/1165731/202009/1165731-20200913164130796-1354971690.png)
![328343890 328343890](https://img2020.cnblogs.com/blog/1165731/202009/1165731-20200913164131859-2001089604.png)
redo log 的特点
![328361218 328361218](https://img2020.cnblogs.com/blog/1165731/202009/1165731-20200913164132748-1652180822.png)
![328510984 328510984](https://img2020.cnblogs.com/blog/1165731/202009/1165731-20200913164133569-1569386622.png)
undo log 介绍
![328688109 328688109](https://img2020.cnblogs.com/blog/1165731/202009/1165731-20200913164134401-537528513.png)
![328737218 328737218](https://img2020.cnblogs.com/blog/1165731/202009/1165731-20200913164135234-476592279.png)
重做日志文件查看
![328745109 328745109](https://img2020.cnblogs.com/blog/1165731/202009/1165731-20200913164135993-1011840621.png)
mysql root@localhost:(none)> show variables like '%undo%'
+--------------------------+------------+
| Variable_name | Value |
+--------------------------+------------+
| innodb_max_undo_log_size | 1073741824 |
| innodb_undo_directory | ./ |
| innodb_undo_log_truncate | OFF |
| innodb_undo_logs | 128 |
| innodb_undo_tablespaces | 0 |
+--------------------------+------------+