Selects the most recent BatchID between the offlineStore and the BatchID calculated with batchesToKeep.
Selects the most recent BatchID between the offlineStore and the BatchID calculated with batchesToKeep. The more recent BatchID is used as the begining of the range used to query the onlineStore.
Pivot to pivot (K, BatchID) pairs into K -> (BatchID, V).
Pivots each BatchID out of the key and into the Value's future.