Replica-Group Leadership Change as a Performance Enhancing Mechanism in NoSQL Data Stores

In this paper we investigate replica-group reconfiguration as a way to mask performance bottlenecks on the primary node of a primary-backup replication group in a NoSQL data store. We investigate the benefit of changing replica-group leadership prior to resource-intensive background tasks such as LSM-tree compactions or data backups on the primary node, a method that can improve throughput by up to 23% during LSM-tree compactions and by 35% during backup tasks. Our implementation is based on MongoRocks (MongoDB 3.7 and RocksDB 5.7) using leveled compaction. We experimentally demonstrate the performance impact of compactions and data backups when they occur at replica-group primaries, and the benefits of targeted leadership-change actions. We evaluate our system using the Yahoo Cloud Serving Benchmark (YCSB) and compare to unmodified MongoRocks on dedicated infrastructure.