WordPress.org

This doesn't do anything!

Yes it does. Hey, didn't you ask this question over on my other plugin too?

I need the cache to be cleared at a different interval than 5 minutes.

Change $cacheMoney->threshold to whatever number of seconds you wish.

How can I tell if this is working?

The directory wp-content/plugins/wpdb-cache-money/ should be full of files with names similar to 4a13fc6a615ac14cc3f58160ce9c52f3.php. If not, check to make sure this directory is writable by your server. echo $wpdb->stats(TRUE) will give you a result like q: 9 | c: 6 | m: 9.055 t: 0.171. q is the number of actual database queries, c is the number of cached queries, m is the memory usage in megabytes, and t is the time in seconds to render the page. echo $wpdb->stats() will do the same, wrapped in an html comment, for times when you need to be discrete. There is also a profiler method - echo $wpdb->profiler(). You will need to make sure $cacheMoney->useProfiler is set to TRUE to use this. The default for the profiler is to sort the queries by length of time descending. $wpdb->profiler(FALSE) will show the queries in the order performed.