# 日志

- `undo log`
  - 事务回滚
  - MVCC
- `redo log`
  - 持久性保证（掉电恢复）
- `binlog`
  - 数据备份
  - 主从复制

![redo log](https://cdn.xiaolincoding.com/gh/xiaolincoder/mysql/how_update/wal.png?image_process=watermark,text_5YWs5LyX5Y-377ya5bCP5p6XY29kaW5n,type_ZnpsdHpoaw,x_10,y_10,g_se,size_20,color_0000CD,t_70,fill_0)

**两阶段提交**
- redo log
- binlog

![两阶段提交](https://cdn.xiaolincoding.com/gh/xiaolincoder/mysql/how_update/%E4%B8%A4%E9%98%B6%E6%AE%B5%E6%8F%90%E4%BA%A4.drawio.png?image_process=watermark,text_5YWs5LyX5Y-377ya5bCP5p6XY29kaW5n,type_ZnpsdHpoaw,x_10,y_10,g_se,size_20,color_0000CD,t_70,fill_0)