Mysql slow query Analysis Method

This article mainly introduces the MySQL slow query analysis method. Some days ago, I set a record to query SQL statements that are slower than 1 second in the MySQL database. There are several very well-configured methods, and the names of several parameters cannot be remembered, so I made a note again.

For troubleshooting and identifying performance bottlenecks, the most common problems are slow MySQL queries and queries without indexes.

OK. Start to find the SQL statement that is not "refreshing" in MySQL.

　MySQL slow query Analysis Method 1:

I am using this method.

MySQL and later versions Support recording slow SQL statements.

MySQL> show variables like long %;

Note: This long_query_time is used to define how many seconds are slower to calculate as "Slow query"

+ ----------------- + ----------- +
| Variable_name | Value |
+ ----------------- + ----------- +
| Long_query_time | 10.000000 |
+ ----------------- + ----------- +
1 row in set (0.00 sec)
MySQL> set long_query_time = 1;

Note: I set 1, that is, if the execution time exceeds 1 second, the query is slow.

Query OK, 0 rows affected (0.00 sec)
MySQL> show variables like slow %;
+ --------------------- + --------------- +
| Variable_name | Value |
+ --------------------- + --------------- +
| Slow_launch_time | 2 |
| Slow_query_log | ON |

Note: whether to Enable Logging

| Slow_query_log_file |/tmp/slow. log |

NOTE: Where to set