说明
1、在MySQL对于join操作的处理过程中,join buffer是一个重要的概念。
2、是MySQL对于table join的一个重要的优化手段。虽然这个概念实现并不复杂,但是这个是实现MySQL join连接优化的一个重要方法,在连接的时候可以极大提高join查询的效率。
实例
Table name Type t1 range t2 ref t3 ALL The join is then done as follows: - While rows in t1 matching range - Read through all rows in t2 according to reference key - Store used fields from t1, t2 in cache - If cache is full - Read through all rows in t3 - Compare t3 row against all t1, t2 combinations in cache - If row satisfies join condition, send it to client - Empty cache - Read through all rows in t3 - Compare t3 row against all stored t1, t2 combinations in cache - If row satisfies join condition, send it to client
以上就是MySQL中join buffer的介绍,希望对大家有所帮助。更多mysql学习指路:MySQL
推荐操作系统:windows7系统、mysql5.8、DELL G3电脑
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