请教MYSQL里JOIN操作与SORT操作内存的问题

一般的nested loop join都是把内存分为3块,一块用来存放较小的TABLE,一块用来存放较大TABLE的一部分,一块用来存放结果准备输出.
请问在MYSQL里的JOIN_BUFFER也是这么分的吗? 还是JOIN_BUFFER只负责存放JOIN的两个TABLE?
另外BUFFER分配的比例是怎么样了?
还想请教下SORT操作时SORT_BUFFER的分配是怎么样的呢?
最好能提供相关函数 谢谢

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这个问题，估计需要等你看完源代码才能回答了。

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mysql 设置join_buffer_size 才被应用

Assume that a join between three tables t1, t2, and t3 is to be executed using the following join types:
Table  Join Type
t1      range
t2      ref
t3      ALL
If a simple NLJ algorithm is used, the join would be processed like this:
for each row in t1 matching range {
  for each row in t2 matching reference key {
    for each row in t3 {
      if row satisfies join conditions,
      send to client
    }
  }
}
Because the NLJ algorithm passes rows one at a time from outer loops to inner loops, tables processed in the inner loops typically are read many times.

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JOIN_BUFFER 和 SORT_BUFFER都可以在配置文件中配置　调优的时候可能会用到