Supporting Elastic Compaction of LSM-tree with a FaaS Cluster

LSM-tree is widely used as a write-optimized storage engine in many key-value stores. However, the periodical compaction operations in LSM-tree cost many I/O bandwidths and CPU resources of the local server, resulting in throughput drops of the system. To address this issue, this paper proposes a new compaction scheme based on a FaaS (Functions as a Service) cluster, which is called FaaS Compaction. It utilizes the elastic computing capability of FaaS clusters and pushes compactions to a FaaS cluster. The FaaS cluster will perform actual compaction operations, which will not affect the processing of the local server. Therefore, we can maintain stable performance even when periodical compactions are triggered. We implement the FaaS Compaction and compare the FaaS Compaction with RocksDB and the state-of-the-art offloading compaction policy. The results suggest the efficiency and elasticity of our proposal.