Can you see other users' session variables in MySQL?

In MySQL, Using SHOW GLOBAL VARIABLES gives the ability to see global variables.
SHOW SESSION VARIABLES are the variable settings for that session.

Is there a way to see the SESSION variables of other active, connected users, from a superuser connection? For example, is there a query or view that would show me which active sessions have variables set differently from the global variables?

As of MySQL 5.7 the performance_schema can provide this information.


Is there a way to see the SESSION variables of other active, connected users, from a superuser connection ?

You can get these from performance_schema.variables_by_thread.

You will need to know the Thread ID. The ID from SHOW PROCESSLIST is Process ID. Knowing the Process ID you can then look up the Thread ID from performance_schema.threads.


is there a query or view that would show me which active sessions have variables set differently from the global variables?

You sure can.

SELECT VARIABLE_NAME, gv.VARIABLE_VALUE, tv.VARIABLE_VALUE
FROM performance_schema.global_variables gv
  JOIN performance_schema.variables_by_thread tv USING (VARIABLE_NAME)
WHERE gv.VARIABLE_VALUE <> tv.VARIABLE_VALUE
  AND THREAD_ID = ?;

StackExchange Database Administrators Q#65144, answer score: 12