One of the essential problems with the covering the NoSQL movement is that it describes not what the associated databases are, but what they are not (and doesn’t even do that very well since SQL itself is in many cases orthogonal to the problem the databases are designed to solve).
It is interesting to see fellow analyst Curt Monash facing the same problem. As he notes, while there seems to be a common theme that “NoSQL is Foo without joins and transactions,” no one has adequately defined what “Foo” is.
Curt has proposed HVSP (High-Volume Simple Processing) as an alternative to NoSQL, and while I’m not jumping on the bandwagon just yet, it does pass the Ronseal test (it does what it says on the tin), and it also matches my view of what defines these distributed data store technologies.
There are numerous categorizations of the various NoSQL technologies available on the Internet. Without wishing to add yet another to the mix, I have created another one – more for my benefit than anything else.
It includes a list of users for the various projects (where available), and also some sense of whether the various projects fit into CAP Theorem, an understanding of which is, to my mind, essential for understanding how and why the NoSQL/HVSP movement has emerged (look out for more on CAP Theorem in a follow-up post on alternatives to NoSQL).
Here’s my take, for those that are interested. As you can see there’s a graph database-shaped whole in my knowledge. I’m hoping to fill that sooner rather than later.
By the way, our Spotlight report introducing The 451 Group’s formal coverage of NoSQL databases will be available here imminently.
Update: VMware has announced that it has hired Redis creator Salvatore Sanfilippo, and is taking on the Redis key value store project. The image below has been updated to reflect that, as well as the launch of NorthScale’s Membase.