1. An optimistic multiversion concurrency control system, comprising: a concurrency control component configured to enforce isolation among concurrently executing transactions operating on data in at least one data store by verifying, with respect to at least one read-write transaction of the transactions, that all data reads of the at least one read-write transactions yield the same result if the data reads were to be repeated at the end time of the at least one read-write transaction, wherein the at least one read-write transaction includes at least one read operation over the at least one data store and at least one write operation over the at least one data store, and wherein the at least one write operation creates a new version of a data record of the at least one data store, and wherein each version of data records of the at least one data store is assigned at least two timestamps indicating a lifetime of the version.