Low-Overhead Asynchronous Checkpointing in Main-Memory Database Systems

Abstract

As it becomes increasingly common for transaction processing systems to operate on datasets that fit within the main memory of a single machine or a cluster of commodity machines, traditional mechanisms for guaranteeing transaction durability---which typically involve synchronous log flushes---incur increasingly unappealing costs to otherwise lightweight transactions. Many applications have turned to periodically checkpointing full database state. However, existing checkpointing methods---even those which avoid freezing the storage layer---often come with significant costs to operation throughput, end-to-end latency, and total memory usage. This paper presents Checkpointing Asynchronously using Logical Consistency (CALC), a lightweight, asynchronous technique for capturing database snapshots that does not require a physical point of consistency to create a checkpoint, and avoids conspicuous latency spikes incurred by other database snapshotting schemes. Our experiments show that CALC can capture frequent checkpoints across a variety of transactional workloads with extremely small cost to transactional throughput and low additional memory usage compared to other state-of-the-art checkpointing systems.