不可重复读与脏读之间的区别 [英] Difference between non-repeatable read vs dirty read

问题描述

来自此 Oracle Java教程:

From this oracle java tutorial:

当事务A检索行时，将发生不可重复的读取， 事务B随后更新该行，事务A随后更新 再次检索同一行.事务A检索同一行 两次，但看到不同的数据.

A non-repeatable read occurs when transaction A retrieves a row, transaction B subsequently updates the row, and transaction A later retrieves the same row again. Transaction A retrieves the same row twice but sees different data.

脏读和不可重复读之间有什么区别?是不是同一回事?由于其他人的更新而读取了错误的结果?

What's the difference between a dirty read and the non-repeatable read? Is it not the same thing? reading the wrong result due to others' updating?

谢谢.

推荐答案

完全相同的页面解释了什么是脏读:

The exact same page explains what a dirty read is:

访问尚未提交的更新值被视为脏读，因为该值可能会回滚到其先前的值.如果您读取的某个值稍后又会回滚，则您将读取一个无效的值.

Accessing an updated value that has not been committed is considered a dirty read because it is possible for that value to be rolled back to its previous value. If you read a value that is later rolled back, you will have read an invalid value.

因此，不可重复读包含读取两个不同的提交值，而脏读包含读取尚未提交的值.完全不同.

So, non-repeatable read consists in reading two different committed values, whereas dirty read consists in reading a value that hasn't been committed yet. Quite different.

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