一、概述：
Mysql的explain工具目前还没有Oracle的explain plan工具那么强大，但是结合show profiles工具可以实现相似的效果。show profiles语句用于在当前会话执行的语句的资源使用情况。其具体语法为：
SHOW PROFILE [type [, type] ... ] [FOR QUERY n] [LIMIT row_count [OFFSET offset]] type: ALL | BLOCK IO | CONTEXT SWITCHES | CPU | IPC | MEMORY | PAGE FAULTS | SOURCE | SWAPS二、开启profiling
show variables like '%profil%';set @@session.profiling=1; --会话级别开启
show profiles在Mysql5.6.7之后官方已经不推荐继续使用（deprecated），转而支持performance_schema（感觉老麻烦，还是show profile简单），performance_schema用法详见如下链接：
https://dev.mysql.com/doc/refman/5.6/en/performance-schema-query-profiling.html
三、show profiles的使用
废话不多说，直接3张图说明。（注意：单个query查询用的是show profile不是show profiles）
至于图中各个列的解释，官网说明在此：（即infomation_schema.PROFILING表的说明）
QUERY_ID is a numeric statement identifier. SEQ is a sequence number indicating the display order for rows with the same QUERY_ID value. STATE is the profiling state to which the row measurements apply. DURATION indicates how long statement execution remained in the given state, in seconds. CPU_USER and CPU_SYSTEM indicate user and system CPU use, in seconds. CONTEXT_VOLUNTARY and CONTEXT_INVOLUNTARY indicate how many voluntary and involuntary context switches occurred. BLOCK_OPS_IN and BLOCK_OPS_OUT indicate the number of block input and output operations. MESSAGES_SENT and MESSAGES_RECEIVED indicate the number of communication messages sent and received. PAGE_FAULTS_MAJOR and PAGE_FAULTS_MINOR indicate the number of major and minor page faults. SWAPS indicates how many swaps occurred. SOURCE_FUNCTION, SOURCE_FILE, and SOURCE_LINE provide information indicating where in the source code the profiled state executes.转载于:https://www.cnblogs.com/leohahah/p/8385528.html
