在上面的代码中,execution_plan[8]、execution_plan[9]和execution_plan[10]分别表示prefix_cost、read_cost和eval_cost的值。 总结 通过以上步骤,我们可以连接到MySQL数据库,打开性能模式,执行查询语句,查询Performance Schema表并解析执行计划数据,最终获取到prefix_cost、read_cost和eval_cost等指标的值。 这些指标...
• When EXPLAIN is used with an explainable【可解释的;可说明的;】 statement, MySQL displays information from the optimizer about the statement execution plan. That is, MySQL explains how it would process the statement, including information about how tables are joined and in which order. • ...
Re: QEP (Query Execution Plan) 3219 KimSeong Loh July 07, 2008 06:06PM Re: QEP (Query Execution Plan) 3359 Ashwathi Krishnan July 08, 2008 05:53AM Re: QEP (Query Execution Plan) 3101 KimSeong Loh July 08, 2008 08:36AM Sorry, you can't reply to this topic. It has been closed...
8.8.2 EXPLAIN Output Format 8.8.3 Extended EXPLAIN Output Format 8.8.4 Obtaining Execution Plan Information for a Named Connection 8.8.5 Estimating Query Performance Depending on the details of your tables, columns, indexes, and the conditions in yourWHEREclause, the MySQL optimizer considers many ...
10.8.2 EXPLAIN Output Format 10.8.3 Extended EXPLAIN Output Format 10.8.4 Obtaining Execution Plan Information for a Named Connection 10.8.5 Estimating Query Performance Depending on the details of your tables, columns, indexes, and the conditions in yourWHEREclause, the MySQL optimizer considers man...
Version:MySQL8.0.18,MySQL8.0.28OS:Linux Assigned to:CPU Architecture:Any Tags:optimizer; execution plan; [31 May 2023 13:23] shang canfang Description:In a simple case where the index is relatively small and the row length is long, for a simple query 'select id from sbtest1 where id >...
MySQL Execution Plan--使用Query Rewrite 安装Query Rewrite Plugin 在MySQL的安装目录的share文件夹下,有两个文件用来安装和卸载Query Rewrite Plugin: install_rewriter.sql: 安装脚本 uninstall_rewriter.sql: 卸载脚本 install_rewriter.sql文件中脚本为:
③、如果解析器解析结果是一条未被 cache 的select语句,则将控制权交给 Optimizer,也就是 Query 优化器模块,主要负责对sql语句进行解析(prase)利用内部算法对sql进行解析,生成解析树(parse tree)及执行计划(execution plan)。(解析:一条sql语句有N条执行方案,当选择最优的方案过程,是最消耗资源的)执行sql,交由访...
Query "select SQL_BUFFER_RESULT a, max(b)+1 from test where a = 0 group by a;" also crashes server. For this query the optimizer chooses query execution plan which doesn't use (and thus doesn't create) the result_field of the max function. But the combination of the SQL_BUFFER_RE...
Rick James May 11, 2012 07:16PM Re: Query execution plan 1561 Chris Slominski May 14, 2012 05:27AM Re: Query execution plan 1309 Rick James May 15, 2012 07:22PM Sorry, you can't reply to this topic. It has been closed.