Scenario

Slow queries can degrade the overall performance of a MySQL cluster, so they need to be monitored closely and addressed promptly.

Fluentd can be set up to parse and collect data from MySQL's slow query logs. Applications include:

  1. Sending email alerts if the query time exceeds a particular threshold.
  2. Generate real-time statistics on slow queries by using Elasticsearch as the search backend.

Setup

  1. Install the MySQL slow query plugin by running the following command

    $ fluent-gem install fluent-plugin-mysqlslowquery
    
  2. Open your Fluentd configuration file and add the following lines:

    <source>
      type mysql_slow_query
      path /path/to/mysqld-slow.log
      tag mysqld.slow_query
    </source>
    

    For example, in most cases, the slow query log is located at /var/log/mysql/slow.log, so the above config would be

    <source>
        type mysql_slow_query
        path /var/log/mysql/slow.log
        tag mysqld.slow_query
    </source>
    

    If you are not sure where you slow query logs are, ask the DBA or look into my.cnf

What's Next?

It's time to configure data outputs. Here are some examples.

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