[jeffdavis]

I attended a talk by Instagram post-buyout. That's where I got the impression that sharding was not a huge obstacle for them (though it was significant). Keep in mind their entire data management team was 2 people I think.

My point was that sharding is not an absolute "have it or not". Some features require major engineering efforts to get anywhere at all, but sharding is not one of them.

But if you think the overall effort is less with MongoDB then go for it.