SHOW [GLOBAL] STATUS

I already discussed status variables related to configuration options in Chapter 3. Here I’ll add some information about other status variables. Like server variables, status variables can be global or per-session. When a client connects, the session variables are set to zero. Global variables show the status since server startup or since the most recent FLUSH STATUS query.

When troubleshooting with status variables, don’t just look at isolated values, but instead follow them over time. One huge number in itself may not mean anything; perhaps you’ve just been lucky enough to experience years of uptime. If it’s large and growing rapidly, though, you might be seeing symptoms of a problem.