MySQL性能优化的最佳20条经验【技术文档】 MySQL性能优化的最佳20+条经验 今天，数据库的操作越来越成为整个应用的性能瓶颈了，这点对于 Web应用尤其明显。关于数据库的性能，这并不只是 DBA才需要担心的事，而这更是我 们程序员需要去关注的事情。当我们去设
MySQL性能优化的最佳20条经验【技术文档】MySQL性能优化的最佳20+条经验
今天，数据库的操作越来越成为整个应用的性能瓶颈了，这点对于 Web应用尤其明显。关于数据库的性能，这并不只是 DBA才需要担心的事，而这更是我 们程序员需要去关注的事情。当我们去设计数据库表结构，对操作数据库时（尤其是查表时的 SQL 语句），我们都需要注意数据操作的性能。这里，我们不会讲过 多的SQL 语句的优化，而只是针对 MySQL这一 Web应用最多的数据库。希望下面的这些优化技巧对你有用。
1. 为查询缓存优化你的查询
大多数的MySQL服务器都开启了查询缓存。这是提高性最有效的方法之一，而且这是被
MySQL的数据库引擎处理的。当有很多相同的查询被执行了多次的时候，这些查询结果会被放
到一个缓存中，这样，后续的相同的查询就不用操作表而直接访问缓存结果了。
这里最主要的问题是，对于程序员来说，这个事情是很容易被忽略的。因为，我们某些查询语句会让 MySQL不使用缓存。
2. EXPLAIN 你的 SELECT 查询
使用 EXPLAIN 关键字可以让你知道 MySQL是如何处理你的 SQL 语句的。这可以帮你分
析你的查询语句或是表结构的性能瓶颈。
EXPLAIN 的查询结果还会告诉你你的索引主键被如何利用的，你的数据表是如何被搜索和排序的……
挑一个你的SELECT 语句（推荐挑选那个最复杂的，有多表联接的），把关键字EXPLAIN
加到前面。你可以使用 phpmyadmin 来做这个事。然后，你会看到一张表格。
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