1. A system for executing bulk data transfers between persistent data stores, comprising: one or more programmatic source interfaces, each being associated with a corresponding source data store, defined according to a common programmatic source interface specification, and exposed during a bulk data transfer to enable extraction from the corresponding source data store of one or more data entities for loading into any one or more selected target data stores during the bulk data transfer; and one or more programmatic target interfaces, each being associated with a corresponding target data store, defined according to a common programmatic target interface specification, and exposed during a bulk data transfer to enable loading into the corresponding target data store of one or more data entities extracted from any one or more selected source data stores during the bulk data transfer; each programmatic interface: providing to the corresponding data store an abstraction of bulk data transfer operations such that custom code need not be developed in connection with the corresponding data store to enable bulk data transfers between the corresponding data store and any other particular data stores; and isolating specific details associated with the corresponding data store such that custom code need not be developed in connection with the bulk data transfer operations to enable bulk data transfers between the corresponding data store and any other particular data stores.