Uniqueness across the cluster
What changes in Uniqueness across the cluster compared with MongoDB and what your application has to do.
This difference is of the Stronger guarantee kind.
What MongoDB does
In a collection with a shard key, _id and unique indexes are only unique within each shard, unless the index has the shard key as a prefix.
What TeselaDB does
_id is unique across the cluster. A unique index is too, without the shard key as a prefix.
What your application has to do
Nothing. You can drop the uniqueness checks you did in your application.