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How to Turn On MySQL Slow Query Log

How To


Summary

Show the steps how to turn on MySQL (MariaDB) slow query log to detect queries that take too long to finish.

Objective

Turn on MySQL slow query log in order to find slow queries that take too long to finish.

Steps

1. To turn on slow query log when MySQL is running

Log in to MySQL as root, and run the following:

SET GLOBAL long_query_time = 1800;
SET GLOBAL slow_query_log_file = '/var/lib/mysql/slow-query.log';
SET GLOBAL slow_query_log = 'ON';

In this case, any query longer than 1800 secs will be logged in /var/lib/mysql/slow-query.log

2. Make the changes permanent, even after MySQL restarts.

In /etc/my.cnf (or /etc/my.cnf.d/server.cnf for MariaDB), add

long_query_time = 1800
slow_query_log_file = /var/lib/mysql/slow_query.log

Document Location

Worldwide


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Document Information

More support for:
IBM Spectrum LSF RTM

Software version:
All Versions

Operating system(s):
Linux

Document number:
1171246

Modified date:
13 January 2020

UID

ibm11171246

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