Quasi Serializability: a Correctness Criterion for Global Concurrency Control in InterBase

In this paper, we introduce Quasi Serializability, a correctness criterion for concurrency control in heterogeneous distributed database environments. A global history is quasi serializable if it is (conflict) equivalent to a quasi serial history in which global transactions are submitted serially. Quasi serializability theory is an extension of serializability. We study the relationships between serializability and quasi serializability and the reasons quasi serializability can be used as a correctness criterion in heterogeneous distributed database environments. We also use quasi serializability theory to give a correctness proof for an altruistic locking algorithm.