关键词: 事务, 云计算, 强快照隔离, 强提交读隔离

Abstract: Current cloud storage system only supports weak consistency and single-key transaction. Developers have to check consistency and manage transactions in applications that need strong consistency and multi-key transaction. Such leads to difficulty in cloud application development. The need for high availability and fault tolerance brings about new challenges to transaction implementation in the cloud. Based on Megastore’s implementation of transaction serializability, this paper proposes two new isolation levels, i.e. snapshot+ isolation and read committed+ isolation. The proposal exploits read/write dataset detection to abort concurrent transactions with read-write and write-write conflicts earlier, avoiding extra communication costs. Both the proposal and Megastore’s approach are implemented on well-known open-source project Cassandra. An evaluation framework targeting the typical transaction patterns of cloud applications is designed to test the implementations. Test results demonstrate that the proposal provides higher concurrency than Megastore’s approach.

Key words: transaction, cloud computing, snapshot+ isolation, read committed+ isolation