1. A method for processing serialized transactions in parallel while preserving: transaction integrity, the method comprising: receiving a transaction from a set of serialized transactions, the transaction comprising at least two keys; accessing a serialization-independent key (“SI-Key”) and a serialization-dependent key (“SD-Key”) from the transaction; assigning the transaction to an execution group based on the value for the SI-Key, the execution group configured to hold one or more transactions; and scheduling the one or more transactions in the execution group for execution in an order defined by each SD-Key value, the execution group configured to execute in parallel with one or more additional execution groups.