What kind of data is this? My best guesses are - either it is SAAS in which case shard it should make sense to shard by customer - or it is something-to-cons

What kind of data is this? My best guesses are - either it is SAAS in which case shard it should make sense to shard by customer - or it is something-to-consumer (social networking?) on which case I guess you'll have to take a step back and see if you can sacrifice one of your current assumptions ... but I feel I'm missing something since what I am saying feels a bit trivial.