[MySQL] 事务隔离级别

DataBase Isolation Levels

隔离级别以及对应级别存在问题

Isolation Level/Problem P0
Dirty Write
P1
Dirty Read
P4C
Cursor Lose Update
P4
Lose Update
p2
Fuzzy Read
P3
Phantom
A5A
Read Skew
A5B
Write Skew
Read Uncommitted Not Possible Possible Possible Possible Possible Possible Possible Possible
Read Committed Not Possible Not Possible Possible Possible Possible Possible Possible Possible
Cursor Stabillity Not Possible Not Possible Not Possible Possible Possible Possible Possible Possible
Repeatable Read Not Possible Not Possible Not Possible Not Possible Not Possible Possible Not Possible Not Possible
Snapshot Not Possible Not Possible Not Possible Not Possible Not Possible Possible Not Possible Possible
Serializable Not Possible Not Possible Not Possible Not Possible Not Possible Not Possible Not Possible Not Possible

隔离级别由弱到强

Degree 0 (everything goes) << Read Uncommitted << Read Committed << Cursor Stability << Repeatable Read << Serializable

这里还有其他2种隔离级别: <font color="green", size="5">Oracle Consistency Read和Snapshot Isolation, Read Committed << Oracle Consistent Read,
Read Committed << Snapshot Isolation << Serializable,
这2种隔离级别都是多版本并发控制机制.

Snapshot Isolation和Repeatable Read并不是对等的, 前者可以防止写偏序(Write Skew), 而Repeatable Read可以防止Snapshot Isolation情况下的一些不能防止的幻读(Phantoms)问题.

隔离级别总结

posted @ 2016-02-28 20:05  Renolei  阅读(562)  评论(1编辑  收藏  举报