As work on WarpSQL (Shard-Query 3) progresses, it has outgrown MySQL proxy.  MySQL proxy is a very useful tool, but it requires LUA scripting, and it is an external daemon that needs to be maintained.  The MySQL proxy module for Shard-Query works well, but to make WarpSQL into a real distributed transaction coordinator, moving the proxy logic inside of the server makes more sense.

The main benefit of MySQL proxy is that it allows a script to “inject” queries between the client and server, intercepting the results and possibly sending back new results to the client.  I would like similar functionality, but inside of the server.

For example, I would like to implement new SHOW commands, and these commands do not need to be implemented as actual MySQL SHOW commands under the covers.

For example, for this blog post I made a new example command called “SHOW PASSWORD”

很久之前看过这个帖子,当时没有细究,这几天看了下mysql相关的internal 突然想起这个问题,跟三四个朋友讨论了下 想把这个问题展开讲一讲。

源帖子内容见：https://community.oracle.com/thread/1087650?start=0&tstart=0

这个帖子的内容为一个老外问oracle如何避免partial write的,也就是大家所说的半个IO问题,IO 在写到一半的时候发生断裂,（瞬间断线,瞬间crash瞬间存储或者机器故障等） 虽然这个情况极少发生,但是在非常规恢复的时候也是经常遇到的,例如某个block内部出现不一致,也就是我们所谓的逻辑坏块。
我仔细的又过了一遍帖子,发现下面的几个回答完全不准确,或者有点张冠李戴的意思。

首先我们看看什么是mysql 的double write:

—–引自 …