noSQL is a big tent with lots of interesting tech in it. A few years ago at work I got an assignment to evaluate graph databases as a possible datastore for our 40-million-pageviews-a-day CMS. Graph DBs are elegant stuff, though not a particularly special fit for that application. Here’s what I had to say. Graph databases are all about “highly connected” data. But instead of tracking relationships through foreign-key mappings RDBMS style, they use pointers that directly connect the related records.
(Note: This is a writeup I did a few years ago when evaluating Riak KV as a possible data store for a high-traffic CMS. At the time, the product was called simply “Riak”. Apologies for anything else that has become out of date that I missed. Also please pardon the stiff tone! My audience included execs who we wanted to convince to finance our mad scientist data architecture ideas.) Riak is a horizontally scalable, fault-tolerant, distributed, key/value store.