Many popular database management systems implement a multiversion concurrency control algorithm called snapshot isolation rather than providing full serializability based on locking. There are well-known anomalies permitted by snapshot isolation that can lead to violations of data consistency by interleaving transactions that would maintain consistency if run serially. Until now, the only way to prevent these anomalies was to modify the applications by introducing explicit locking or ...

DB - Making Snapshot Isolation Serializable.pdf Snapshot Isolation (SI) is a multiversion concurrency control algorithm, first described in Berenson et al. [1995]. SI is attractive because it provides an isolation level that avoids many of the common concurrency anomalies, and has been implemented by Oracle and Microsoft SQL Server (with certain minor variations). SI does not guarantee serializability in all cases, but the TPC-C benchmark application [TPC-C],

This paper describes our experience implementing PostgreSQL’s new serializable isolation level. It is based on the recently-developed Serializable Snapshot Isolation (SSI) technique. This is the first implementation of SSI in a production database release as well as the first in a database that did not previously have a lock-based serializable isolation level. We reflect on our experience and describe how we overcame some of the resulting challenges, including the implementation of a new lock ...

数据库编程 事务隔离级别 课程目标 了解 —— 事务隔离级别的概念； 理解 —— 事务隔离的四种级别； 掌握 —— 事务隔离级别的设置； 事务隔离级别 事务隔离：每一个事务都有一个所谓的隔离级，它定义了用户彼此之间隔离和交互的程度。隔离性强制对事务进行某种程度的隔离，保证应用程序在事务中看到一致的数据。 MySQL提供了下面4种隔离级：序列化（SERIALIZABLE）、可重复读（REPEATABLE READ）、提交读（READ COMMITTED）、未提交读（READ UNCOMMITTED）。 事务隔离级别 语法格式： SET [GLOBAL | SESSION] TRANSACTION ISOLATION LEVEL SERIALIZABLE | REPEATABLE READ | READ COMMITTED | READ UNCOMMITTED 说明：如果指定GLOBAL，那么定义的隔离级将适用于所有的SQL用户；如果指定SESSION，则隔离级只适用于当前运行的会话和连接。MySQL默认为REPEATABLE READ隔离级。 事务隔离级别 序列化 如果隔离级为序列化，用

介绍数据库事务的四种隔离级别，比较不同隔离级别的区别和影响