The Fennel C++ data management library has been under development for quite some time; this is the first packaged GPL release. Features include high-performance asynchronous I/O for database files; page-based storage allocation and caching; extensible transaction management; table storage with clustered indexes based on high-concurrency B-link trees; tuple manipulation; query execution stream dataflow scheduling; SQL expression execution; and high-performance external sorting.
For more information, please visit http://fennel.sourceforge.net.