Why In-Memory Data Grids are more technically advanced than NoSQL products?

We had this discussion in office another day and I couldn’t figure our why popular NoSQL products like MongoDB, CouchDB, Cassandra, etc. are generally years behind on some of the core scalability and performance technologies behind established In-Memory Data Grid vendors like Coherence, GridGain, GigaSpaces, GemFire?

It’s not a feature by feature comparison that I’m talking about - all of these products has plenty of unique features. It’s just the fact that while IMDG were scaling to 100s and 1000s of nodes and working in mission critical systems for years now - NoSQL products are simply not there and moving there rather slowly (if at all).

I can’t remember ever having IMDG product with a global-lock based implementation (like the MongoDB “engineered”), as an illustration to what I’m talking about it.

Than it downed on me while here at HPC for Wall Street conference (where not a single NoSQL vendor was present, btw): it’s customers...

Look, 90% of NoSQL usage comes from the same crowd as a typical memcached users: non-critical, “moms-n-pops” websites. 90% of IMDG/IMCG usage comes from mission critical systems.

Different customers => different requirements => different products...