RocksDB

RocksDB is a high-performance, embeddable key-value store: optimized for fast storage and server workloads.

RocksDB is an open-source, persistent key-value store, forked from Google's LevelDB in 2012 and engineered by Meta (formerly Facebook). It leverages a Log-Structured Merge-tree (LSM-tree) architecture, specifically optimized to exploit multi-core CPUs and fast storage like SSDs for I/O-bound workloads. This C++ library is designed to be embedded directly into applications (not a standalone server), eliminating network latency. Key features include support for transactions, Column Families, and merge operators. Its performance profile makes it the storage engine of choice for production systems like MySQL's MyRocks, CockroachDB, and Apache Flink's state store.

https://rocksdb.org/