[Spoutingshite]

In our experience, sharding at the application level is to be avoided.

We implemented application level sharding a few years ago when we had 1Tb of data. We now have over 20Tb of data and application level business logic is killing us.

Our pain is not DB speed, but application complexity. All of our applications (backup, web, maintenance, archiving etc) all need the business logic to traverse the sharding set.

We are planning to move to DB level sharding in January (as part of a larger application and infrastructure refresh).