LMDB noSQL database
Robin Rowe's fork of LMDB is much less to download than taking all of OpenLDAP, accepts patches, removed compile warnings, and adds a C++ wrapper to the the canonical OpenLDAP source code.
From https://en.wikipedia.org/wiki/Lightning_Memory-Mapped_Database
Lightning Memory-Mapped Database (LMDB) is a software library that provides an embedded transactional database in the form of a key-value store. LMDB is written in C with API bindings for several programming languages. LMDB stores arbitrary key/data pairs as byte arrays, has a range-based search capability, supports multiple data items for a single key and has a special mode for appending records (MDB_APPEND) without checking for consistency.[1] LMDB is not a relational database, it is strictly a key-value store like Berkeley DB and dbm.