“…P ERSISTENT key-value (KV) stores are an integral part of storage infrastructure in data centers and have been used in many applications including cloud storage [1], online games [2], advertising [3], [4], e-commerce [5], web indexing [3], [6], and social networks [4], [7], [8]. KV stores can be divided into three categories depending on the index structure used: hash index-based design [9], [10], B-tree-based design [11], and log-structured merge (LSM)-tree-based design [12]. Among them, the LSM-tree-based KV stores, such as BigTable [3], Cassandra [13], LevelDB [6], [14], RocksDB [4], and Hbase [15], are state-of-the-art persistent KV stores for write-intensive workloads.…”