Bring RocksDB to PostgreSQL as an extension. It is the first foreign data wrapper (FDW) that introduces LSM-tree into PostgreSQL. The underneath storage engine can be RocksDB. The FDW also serves for VidarDB engine, a versatile storage engine for various workloads. See the link for more info about VidarDB engine.
VidarDB engine is a modern embedded key-value store with a versatile storage engine. It is a lineage of LevelDB and RocksDB, but with support of various workloads.
PyVidarDB is a simple, fast, and persistent key-value store that can store terabytes of data. It is the Python binding for VidarDB.