I'm wondering if it has been considered to buffer the metrics into a memory table so they can participate in queries, and then let MySQL flush them to durable tables at regular intervals?
My personal opinion on that is that it's another layer of complexity without too much to gain. It's something else to manage (operational overhead), and something else to interact with (programmer overhead).
MySQL by itself is plenty fast for us. As Baron mentioned, we don't even run the database servers at full capacity.
