Hyeongjun Jeon  Hera Koo  Sungho Moon  Beomseok Nam

10.5626/JOK.2023.50.1.87

LSM-tree NoSQL Index

Key-Value store, which is one of the NoSQL databases, uses Log-Structured Merge Tree(LSM Tree) as its index data structure. LSM Tree normally has good writing performance, but write amplification and write stall as chronic problems in LSM Tree have impeded the write performance of LSM Tree. In this paper, we introduce Extended MemTable which is an extended version of the current LSM Tree’s MemTable considering that recent datacenter’s main memory space is increasing. Extended Memtable uses partition which is divided by key ranges. It does the flush operation in the manner that the compaction operation can be operated effectively. It can increase the write throughput by up to 2 x and the read throughput by up to 4 x while reducing write amplification by up to 3.7 x compared to the original RocksDB by significantly reducing write amplification and write stall problems.