1. A method comprising: in response to receiving a transaction, accessing, by use of at least one processor, a transaction serialization-independent key (SI-Key) and a predefined transaction serialization-dependent key (SD-Key) of the received transaction; in response to a determination that an existing execution group of a plurality of execution groups is not associated with the transaction SI-Key and an execution group limit is reached, assigning the received transaction to the existing execution group; and in response to a determination that the existing execution group is not associated with the transaction SI-key and the execution group limit is not reached, assigning the received transaction to a new execution group; wherein a plurality of transactions assigned to any execution group of the plurality of execution groups are executed serially in an order based on transaction SD-Keys; and wherein the plurality of transactions assigned to any execution group of the plurality of execution groups are executed in parallel with transactions assigned to other execution groups.