From a performance standpoint, sometimes even tightly tuned queries can cause a performance drag. The common problem here is not one of actual query performance, rather it is a function of:
- the velocity and frequency that a query is submiited for execution
- the total execution time of the aggregated executions
This could be symptomatic of an application not properly configured for caching (see Darren Oldag's blog on this!), or just overall poor design. Regardless of why, when or how we all know it happens. The trouble with this particular problem is that when a query is tuned, or very simple, it is usually not suspect for being a resource hog. Pulling aggregates for number of execs and total exec time for specific queries is a little tricky and labor intensive with the Slow Query Log, and not really a good option for SHOW PROCESSLIST. With this in mind, we designed the Query Analyzer to aggregate these values for quick reference in the Enterprise Monitor. Take a look:
We have also been listening when Mark Callaghan talks about reporting rollups for the top-N objects that are consuming resources on the server. Given we will probably have to wait until 6.0 to get the SHOW STATS extensions for this, we are looking at creative ways we can do this now using the proxy and Monitor service agent.