FlashKey:A High-Performance Flash Friendly Key-Value Store

Abstract

Key-value stores (KVS) provide an efficient storage for increasing amounts of semi-structured or unstructured data generated by many applications. Most KVS in existence have been designed for hard-disk based storage where avoiding random accesses is crucial for good performance. Unfortunately, the resulting storage structures result in high read, write, and space amplifications when used on modern SSDs. In this paper, we introduce a KV store especially designed for SSDs, called FlashKey, and demonstrate that even as an initial implementation, it substantially outperforms the two most popular commercial KVS in existence, namely, Google’s LevelDB and Facebook’s RocksDB. In particular, we show that FlashKey achieves up to 85% improvement in average access latency, 2x improvement in tail latencies, and 12x improvement in write amplification, at comparable or better space-amplification. Furthermore, FlashKey can easily trade off space and write amplifications, thereby providing a new tuning knob that is difficult to implement in LevelDB and RocksDB.