TwinDB is an embedded key/value database based on
BerkeleyDB. It basically adds security from
database corruption on top of the
non-transactional version of BerkeleyDB. It
accomplishes this by maintaining twin BerkeleyDB
databases and using "lock" files to indicate when
a set of writes are in progress. Performance is
still good (tested at ~60K writes/sec and 300K
reads/sec). It was written because the
transactional version of BerkeleyDB is expensive.
