Great when you are a huge company with massive number of data and operations where every ms counts, but in most cases there are bigger and more important things to optimize before saving some round trips from the db.
But, in many (if not most) situations the ms you loose by doing more round trips then necessary are not worth how much more maintainable the system is.
Especially when there is probably some programming or query optimization that will save you seconds, when reducing the round trips is a matter of ms.
But micro optimization has always the same caveat:
Of course it is not irrelevant, it might even be very important, in very specific cases.
But if you are not one of those cases (and you should already know if you are) you shouldn't even bother with it.
Of course as a VoltDB employee, we have a number of smaller customers who use VoltDB because it allows a small shop to do things that would be too expensive with a traditional system. Just because you’re small, doesn’t mean you don’t have a high-throughput problem.
One example is Xacte, which tracks marathon bibs as they fly by RFID sensors in the course. The issue is when 50 people run by a sensor in one second, the de-duplification code in the sensor sometimes breaks down, and their system gets hundreds of triggers. They literally have a van full of equiptment that includes a small VoltDB cluster keeping accurate runner positioning for events like the LA Marathon.