How can I Enable MySQL\'s Slow Query Log without Restarting the Server?

Setting MySQL's Slow Query Log without Rebooting

Enabling MySQL's slow query log without restarting the server can be a convenient way to quickly troubleshoot performance issues. Here's a detailed guide on how to accomplish this:

Configuring the Log File

By default, MySQL creates the slow query log file in the data directory with a name of host_name-slow.log. To specify a different directory, provide an absolute path name.

Setting the Threshold and File Location

Setting the threshold alone does not suffice for enabling the slow query log. You need to additionally configure the file location.

Using SET GLOBAL Command

For MySQL versions 5.1 or later, use the following command to enable and configure the slow query log:

SET GLOBAL slow_query_log = 'ON';

Refreshing the Log

To apply the changes, you can flush the log using the following command:

FLUSH LOGS;

Handling Exceptions

For MySQL versions earlier than 5.1, setting the slow query log via the SET GLOBAL command will result in an error. In such cases, you'll need to restart the server or set the log_slow_queries option in the MySQL configuration file and restart the server.

참고 사항

Remember that enabling the slow query log can impact performance, so it's recommended to disable it after troubleshooting or capturing the necessary data.

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