There is a performance issue that causes collections with views to have substantially decreased performance if the collection lives on a different shard than the view. This isn't currently an issue for unsharded collections because all collections and views live on the dbPrimary.

However, once the balancer starts moving unsharded collections, it could be possible that the balancer chooses to move a collection with a view to a shard other than the dbPrimary. We should not allow this because it would reduce the performance on this view.

Because the balancer is located on the config server and so does not know which collections have views, it will be the responsibility of the shard donating the collection to check before beginning the moveCollection command and throw an error if the collection has a view and the destination shard is not the dbPrimary.