mysql 查询语句性能分析

Question

有什么工具可以分析记录 一条查询语句吗？比如说在那条语句中，查询哪个字段用时最多。

Answer 1

Records stored in mysql are generally not divided into fields and are stored as a whole.
Tools for optimizing SQL include: explain: used to analyze whether to apply indexes and the number of scanned records; slow log generally records SQL statements whose execution time is greater than a certain value; show profiles generally analyzes data on IO, Memory, CPU, etc.

Answer 2

Use execution plan, explain

Answer 3

Set in my.cnf

php[mysqld] 
slow_query_log=on 
slow_query_log_file=mysql-slow

Slow query log analysis tool officially provided by mysqlmysqldumpslow mysql-slow
Also mysqlsla

Answer 4

Use explain command

Answer 5

Must explain

Answer 6

It is recommended to use Alibaba's druid database connection pool. Configure it to record all SQL execution statistics for a period of time. There will be a web page that can be accessed, which is very helpful for SQL execution analysis. However, the cache of this thing takes up a lot of space, and it cannot count long-term running conditions. It is very suitable for analyzing the amount of data for several hours.