JavaJavaStar[https://github.com/Snailclimb/Java_Guide](https://github.com/Snailclimb/Java_Guide)

> ## 

**MySQL : 3**

> ## 

[MySQL ](http://www.runoob.com/mysql/mysql-tutorial.html)

[MySQL](https://www.yiibai.com/mysql/)

> ## 


**** [MySQL-](https://www.imooc.com/learn/122)

**Mysql** [MySQL](https://www.imooc.com/learn/398)[MySQL](https://www.imooc.com/learn/427)[MySQL](https://www.imooc.com/learn/449)

**Mysql5.7** [MySQL5.7](https://www.imooc.com/learn/533)[MySQL](https://www.imooc.com/learn/194)

[MySQLPXC](https://www.imooc.com/learn/993)[MyCAT](https://www.imooc.com/learn/951)


> ## 

- ### 

  [MySQLMyISAMInnoDB](https://juejin.im/post/5b1685bef265da6e5c3c1c34)
  
- ### 

   Mysql

   Mysql PSJava
   
      [MySQL](https://www.cnblogs.com/geaozhang/p/6724393.html#mysqlyuzifuji)

-  ### 
    
   Mysql**BTree**  **** BTree
   
   MysqlBTreeBB+Tree

   **MyISAM:** B+TreedataB+TreeKey data  data 
   
   **InnoDB:** MyISAMB+TreedatakeyInnoDBdataMyISAM**key** **** PSJava
   
    
    
    [mysql](https://www.jianshu.com/p/1775b4ff123a)
    
    [MySQL--](https://blog.csdn.net/Jack__Frost/article/details/72571540)
 
    [](https://juejin.im/post/5b55b842f265da0f9e589e79#comment)
    
- ### 

   my.cnfMysql
   ```
   query_cache_type=1
   query_cache_size=600000
   ```
   
   Mysql
   
   ```
   set global  query_cache_type=1;
   set global  query_cache_size=600000;
   ```
   ****Mysql
   
   Mysql
   
   **** MB**sql_cachesql_no_cache**
   ```
   select sql_no_cache count(*) from usr;
   ```
   
- ### 
   
   **ACID**

![](https://user-gold-cdn.xitu.io/2018/5/20/1637b08b98619455?w=312&h=305&f=png&s=22430)

   1.  **** 
   2.  **** 
   3.  **** 
   4.  ****  
   
  ****

-  **READ_UNCOMMITTED:** ****
-  **READ_COMMITTED:** 	****
-  **REPEATABLE_READ:** 	****
- **SERIALIZABLE:** 	ACID****

  **Mysql  REPEATABLE_READ Oracle  READ_COMMITTED.**

  MVCC

      [Spring](https://blog.csdn.net/qq_34337272/article/details/80394121)

- ### InnoDB
   **MyISAMInnoDB**

  - MyISAM(table-level locking)
  - InnoDB(row-level locking),

   ****

    - **** Mysql **** MyISAM InnoDB
   - **** Mysql ****   

   
   [Mysql](https://blog.csdn.net/qq_34337272/article/details/80611486)
   
  **InnoDB**
   - Record lock
   - Gap lock
   - Next-key lockrecord+gap 
 
   ****
    1. innodbnext-key lock
    2. Next-locking keyingPhantom Problem
    3. next-key lockrecord key
    4. Gap
    5. gaprecord lock A. RC B. innodb_locks_unsafe_for_binlog1

-  ### 

   MySQLCRUD
  
  1. **** 
  2. **/** 
  3 . **** 
     
      **** 

      **** 
    ![](https://user-gold-cdn.xitu.io/2018/6/16/164084354ba2e0fd?w=950&h=279&f=jpeg&s=26015)
  
      **** BlockI/O

      **** JoinJoin

  4. **** 
  
   
     ** ** 
   
     200
   
     ![](https://user-gold-cdn.xitu.io/2018/6/16/164084b7e9e423e3?w=690&h=271&f=jpeg&s=23119)
   
     :MySQL **** 
   
      **** ****  JoinJava **** I/O
   
     ****
     - ****  **jarJDBC**  **Sharding-JDBC** TDDL
     - **** ****  **Mycat** 360AtlasDDB
  
  
  
  [MySQL](https://segmentfault.com/a/1190000006158186)