Two-Stage Transaction Processing in Client-Server DBMSs

In this paper, we show that there is scope for replication in data-shipping client-server DBMSs offering opportunities for improved transactionresponse times. To support this replication, we describe a two-stage protocol for transaction processing (2STP). We extend the conventional clientserver data-shipping mechanism by allowing clients to update and query cached objects that have replicas in multiple sites. We use the concept of acceptance criteria to provide a means for flexible handling of client updates. The effectiveness of the two-stage transaction processing mechanism is supported by means of queuing analysis and detailed simulationexperiments comparing 2STP with a global lockbased data-shipping protocol. This improvement in transaction processing efficiency is achieved at the cost of longer downtimes for crash recovery.