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This article mainly explains "how to locate slow SQL in MySQL". The content in the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn how to locate slow SQL in MySQL.

The direct performance loss caused by slow logs is the most expensive I SQL O resource in the database system. The advantage of turning on slow query records is that SQL statements can be optimized by analyzing slow log.

The steps to enable the slow log feature are as follows:

1) add the following parameters to the my.cnf configuration file:

Slow_query_log=1

Slow_query_log_file=/mysql/data/mysql.slow

Long_query_time=2 (SQL of more than 2 seconds will be recorded)

2) when the number of database connections is high, the slow logs of this period are intercepted through the time point at that time, such as:

Sed-n'/ # Time:110720 16 purge 17purl 40lemag.myqlUniqql.slow > slow.log

Then use the mysqldumpslow command to take out the first 10 slow SQL which takes the longest time for analysis.

Mysqldumpslow-s t-t 10 slow.log

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