The most compelling argument that I have heard is from this video here. Keep in mind I have not verified the information, but from a high level, it makes sense.
The argument being, SQL databases are optimized for memory. Which made sense for when they were made because memory was one of the most expensive pieces in a datacentre. Now memory is fairly cheap and CPU’s have become the most expensive pieces in a datacentre. NoSQL apparently optimizes for the CPU, which is why it generally has a fairly “dumb” querying mechanism.
But to me, that just seems to move the CPU usage from the database and into your application(s). So I don’t really know how it is a win.
I just wish I had a lot of time to dig deep into as many databases as I could in order to find what each of their use cases are. Unfortunately for me, I don’t have that time.
