# 8.1 mysql缓存.md

在MySQL 5.6开始，就已经默认禁用查询缓存了。在MySQL 8.0，就已经删除查询缓存功能了。

将select语句和语句的结果做[hash](https://so.csdn.net/so/search?q=hash\&spm=1001.2101.3001.7020)映射关系后保存在一定的内存区域内。

禁用原因：

1.命中率低

2.写时所有都失效

禁用了：<https://mp.weixin.qq.com/s/\\_EXXmciNdgXswSVzKyO4xg。>

查询缓存讲解：<https://blog.csdn.net/zzddada/article/details/124116182>


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# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://gitbook.wenzhihuai.com/ba-mysql/shu-ju-ku-huan-cun.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.