Abstract: At present, there are a large number of writing-intensive loads (e.g., secondkilling of e-commerce, social user-generated data streams) in many applications such as e-commerce, social networking, mobile Internet and so on, which makes log-structured storage a popular technique for back-end storage of modern database systems. However, log-structured storage only supports the append operation, efficient primary key management (primary key generation and update) functions can improve the performance of database append operations. In the distributed and concurrent environment, implementing primary key maintenance faces challenges, such as primary key unique constraints, transactional maintenance, and high-performance requirements. In light of the characteristics of log-structured storage, this paper explores how to implement efficient primary key management in distributed log-structured database systems. First, we propose two kinds of concurrency control models for WAR (Write After Read) operations; second, we adopt these two models to design efficient primary key management algorithms; and finally, we integrate these algorithms into our distributed log-structured database, CEDAR, and verify the effectiveness of the proposed methods by a series of experiments.

Key words: log-structured, distributed database, primary key management, concurrent environment