How can I view live MySQL queries?

Solution 1:

You can log every query to a log file really easily:

mysql> SHOW VARIABLES LIKE "general_log%";

+------------------+----------------------------+
| Variable_name    | Value                      |
+------------------+----------------------------+
| general_log      | OFF                        |
| general_log_file | /var/run/mysqld/mysqld.log |
+------------------+----------------------------+

mysql> SET GLOBAL general_log = 'ON';

Do your queries (on any db). Grep or otherwise examine /var/run/mysqld/mysqld.log

Then don't forget to

mysql> SET GLOBAL general_log = 'OFF';

or the performance will plummet and your disk will fill!

Solution 2:

You can run the MySQL command SHOW FULL PROCESSLIST; to see what queries are being processed at any given time, but that probably won't achieve what you're hoping for.

The best method to get a history without having to modify every application using the server is probably through triggers. You could set up triggers so that every query run results in the query being inserted into some sort of history table, and then create a separate page to access this information.

Do be aware that this will probably considerably slow down everything on the server though, with adding an extra INSERT on top of every single query.

Edit: another alternative is the General Query Log, but having it written to a flat file would remove a lot of possibilities for flexibility of displaying, especially in real-time. If you just want a simple, easy-to-implement way to see what's going on though, enabling the GQL and then using running tail -f on the logfile would do the trick.

Solution 3:

Even though an answer has already been accepted, I would like to present what might even be the simplest option:

$ mysqladmin -u bob -p -i 1 processlist

This will print the current queries on your screen every second.

• -u The mysql user you want to execute the command as
• -p Prompt for your password (so you don't have to save it in a file or have the command appear in your command history)
• i The interval in seconds.
• Use the --verbose flag to show the full process list, displaying the entire query for each process. (Thanks, nmat)

There is a possible downside: fast queries might not show up if they run between the interval that you set up. IE: My interval is set at one second and if there is a query that takes .02 seconds to run and is ran between intervals, you won't see it.

Use this option preferably when you quickly want to check on running queries without having to set up a listener or anything else.