wiki key-value database DBM LMDB paper The Log-Structured Merge-Tree (LSM-Tree) WiscKey: Separating Keys from Values in SSD-conscious Storage Name that compaction algorithm LSM math: revisiting the number of levels that minimizes write amplification article 如何将SQL数据映射到KV数据库 LevelDB From Scratch in Java From RDBMS to Key-Value Store: Data Modeling Techniques