Abstract: Systems and methods are provided to implement a partitioned data store that transparently manages the partitioning of storage objects. In embodiments, the data store may determine that a user-specified partition key for a storage object is inadequate to properly partition the storage object, and generate another partition key that includes the user-specified partition key and another partition attribute. The data store may allow clients to query and update the data using the user-specified partition key, but transparently rebalance the actual partitions by adjusting the generated partition key. In embodiments, the data store may monitor usage metrics for its partitions, and take rebalancing actions (e.g., splitting partitions or relocating partition data) to dynamically maintain balance among the partitions. In embodiments, the data store may provide an analytics interface that displays the usage metrics for the different user-specified partitions.