Scalable versioning in distributed databases with commuting updates

Presents a multiversioning scheme for a distributed system with the workload consisting of read-only transactions and update transactions, (most of) which commute on individual nodes. The scheme introduces a version advancement protocol that is completely asynchronous with user transactions, thus allowing the system to scale to very high transaction rates and frequent version advancements. Moreover, the scheme never creates more than three copies of a data item. Combined with existing techniques to avoid global concurrency control for commuting transactions that execute in a particular version, our multiversioning scheme results in a protocol where no user transaction on a node can be delayed by any activity (either version advancement or another transaction) occurring on another node. Non-commuting transactions are gracefully handled. Our technique is of particular value to distributed recording systems where guaranteeing global serializability is often desirable, but rarely used because of the high performance cost of running distributed transactions. Examples include calls on a telephone network, inventory management in a “point-of-sale” system, operations monitoring systems in automated factories, and medical information management systems