官方文档

InnoDB implements standard row-level locking where there are two types of locks, shared (S) locks and exclusive (X) locks.

  • A shared (S) lock permits the transaction that holds the lock to read a row.

  • An exclusive (X) lock permits the transaction that holds the lock to update or delete a row.

If transaction T1 holds a shared (S) lock on row r, then requests from some distinct transaction T2 for a lock on row r are handled as follows:

  • A request by T2 for an S lock can be granted immediately. As a result, both T1 and T2 hold an S lock on r.

  • A request by T2 for an X lock cannot be granted immediately.

If a transaction T1 holds an exclusive (X) lock on row r, a request from some distinct transaction T2 for a lock of either type on r cannot be granted immediately. Instead, transaction T2 has to wait for transaction T1 to release its lock on row r.

 shared  lock

A kind of lock that allows other transactions to read the locked object, and to also acquire other shared locks on it, but not to write to it.

exclusive lock

A kind of lock that prevents any other transaction from locking the same row. Depending on the transaction isolation level, this kind of lock might block other transactions from writing to the same row, or might also block other transactions from reading the same row. The default InnoDB isolation level, REPEATABLE READ, enables higher concurrency by allowing transactions to read rows that have exclusive locks, a technique known as consistent read.

MySQL Shared and Exclusive Locks的更多相关文章

  1. Shared and Exclusive Locks 共享和排它锁

    14.5 InnoDB Locking and Transaction Model InnoDB 锁和事务模型 14.5.1 InnoDB Locking 14.5.2 InnoDB Transact ...

  2. If one session has a shared or exclusive lock on record R in an index, another session cannot insert

    If one session has a shared or exclusive lock on record R in an index, another session cannot insert ...

  3. mysql锁之Next-Key Locks

    一个Next-key锁结合了行锁和gap锁. InnoDB执行一个行级别锁在这样的一个途径,那就是它搜索或者扫描一个表索引时,它设置共享或者独占锁在它遭遇的索引记录上.于是,行级锁是真实的行记录锁.一 ...

  4. 转 MYSQL InnoDB Record, Gap, and Next-Key Locks

    http://dev.mysql.com/doc/refman/5.0/en/innodb-record-level-locks.html InnoDB has several types of re ...

  5. 小白学习mysql 之 innodb locks

    Innodb 锁类型: Shared and Exclusive Locks Intention Locks Record Locks Gap Locks Next-Key Locks Insert ...

  6. Mysql讲解数据库并发控制知识

    1.下载Mysql并安装,我喜欢不用安装的zip版,cd到bin目录下,先修改下mysql的密码. mysqladmin -u root -p password mysql ,第一次运行并修改mysq ...

  7. 14.3.3 Locks Set by Different SQL Statements in InnoDB 不同的SQL语句在InnoDB里的锁设置

    14.3.3 Locks Set by Different SQL Statements in InnoDB 不同的SQL语句在InnoDB里的锁设置 locking read, 一个UPDATE,或 ...

  8. mysql锁机制详解

    前言 大概几个月之前项目中用到事务,需要保证数据的强一致性,期间也用到了mysql的锁,但当时对mysql的锁机制只是管中窥豹,所以本文打算总结一下mysql的锁机制. 本文主要论述关于mysql锁机 ...

  9. 转 mysql Next-Key Locking

    原文:http://dev.mysql.com/doc/refman/5.5/en/innodb-next-key-locking.html 14.5.2.5 Avoiding the Phantom ...

随机推荐

  1. linux磁盘空间满了 但是没有大文件

    很常见的一个问题 linux磁盘空间满了 但是没有大文件 解决思路: 1.用df 检查发现/根目录可用空间为0 [root@/]#df -h 2.用du检查发现各目录占用的空间都很少,有约3G的空间莫 ...

  2. oracle 字符集安装错了,修改字符集 及创建用户 表空间 ,删除用户及所有的表

    1.首先以sysdba的身份登录上去 conn /as sysdba 2.关闭数据库shutdown immediate; 3.以mount打来数据库,startup mount 4.设置sessio ...

  3. 【转】大众点评CAT开源监控系统剖析

    https://www.cnblogs.com/yeahwell/p/cat.html 参考文档: 大众点评的实时监控系统分析(一) CAT_source_analyze 透过CAT,来看分布式实时监 ...

  4. DecimalField的使用

    DecimalField类DecimalField(max_digits =无,decimal_places =无[,**选项])固定精度的十进制数,在Python中表示一个 十进制的实例.有两个必需 ...

  5. python预课01 turtle学习

    Turtle命令: import turtle # 导入模块 t = turtle.Pen() # 生成画笔 t.speed() #设置速度0-10:0最快 t.forward() # 前进 t.ba ...

  6. 一台服务器配置多个TOMCAT

    如果要在一台服务器上配置多个Tomcat,主要就是要避免Tomcat服务器的端口冲突的问题.只需要修改CATALINA_HOME\conf\server.xml中的启动端口和连接端口就OK了! 下面我 ...

  7. Mobx | 强大的状态管理工具 | 可以用Mobx来替代掉redux

    来源简书 电梯直达 https://www.jianshu.com/p/505d9d9fe36a Mobx是一个功能强大,上手非常容易的状态管理工具.就连redux的作者也曾经向大家推荐过它,在不少情 ...

  8. 客户端本地存储,web存储,localStorage

    HTML5 LocalStorage 本地存储 说到本地存储,这玩意真是历尽千辛万苦才走到HTML5这一步,之前的历史大概如下图所示: 最早的Cookies自然是大家都知道,问题主要就是太小,大概也就 ...

  9. 如何保护你的 Python 代码 (一)—— 现有加密方案

    https://zhuanlan.zhihu.com/p/54296517 0 前言 去年11月在PyCon China 2018 杭州站分享了 Python 源码加密,讲述了如何通过修改 Pytho ...

  10. 没有内置小鹤双拼的rime输入法就是差劲

    没有内置小鹤双拼的rime输入法就是差劲,还特立独行,搞什么繁体~ 没有内置小鹤双拼的rime输入法就是差劲,还特立独行,搞什么繁体~ 没有内置小鹤双拼的rime输入法就是差劲,还特立独行,搞什么繁体 ...