Peer-to-peer multidatabase systems (P2P MDBSs) are dynamic networks of peers with total absence of any global schema, any central administrative authority, any data integration, any global access to multiple databases, permanent participation of databases, etc. Global and local transactions are supported in P2P MDBSs. A global transaction generates descendent transactions when it is propagated to other peers over acquaintances in a P2P MDBS. Descendent transactions are translations of the original global transaction based on mappings between attributes in two acquainted peers. We present a serializability theory for transactions in P2P MDBSs, and then a concurrency control protocol is proposed to ensure the global serializability of global histories by controlling the consistency over each single acquaintance. The correctness of the concurrency control protocol is proved by using the developed theory. |