Wikipedia
TokuMX is an open source distribution of MongoDB which, among other things, replaces the default B-tree data structure found in the basic MongoDB distribution with a Fractal tree index. It is a drop-in replacement for MongoDB (applications will run "as is") that offers the scalability and performance improvements associated with Fractal Tree indexing. It also adds support for document-level locking, transaction support with ACID and MVCC, and replication optimization; it does not support full-text search.
TokuMX is specifically designed for high performance on write-intensive workloads. It achieves this using a Fractal tree index, which replaces 40-year-old B-tree indexing and is based on cache-oblivious algorithms. This approach to building memory-efficient systems was originally jointly developed by researchers at the Massachusetts Institute of Technology, Rutgers University, and the State University of New York at Stony Brook (SUNY). TokuMX is a scalable, ACID, and MVCC compliant distribution of MongoDB that provides indexing-based query improvements, offers online schema modifications, and reduces slave lag for both hard disk drives and flash memory. It also adds transactions with MVCC and ACID reliability to any MongoDB application, making MongoDB suitable for a much wider range of solutions.
Most TokuMX source files are made available under the terms of the GNU Affero General Public License (AGPL). The TokuKV Fractal Tree Indexing library is made available under the terms of the GNU General Public License (GPL) version 2, with an additional grant of a patent license.