To expand the MVCC list noted above, MySQL + TokuDB is always in MVCC as well (since version 5.0 last year). Also note that the Quora link describes Fractional Cascading. TokuDB uses Fractal Tree indexes. To learn more about Fractal Tree indexes as opposed to basic LSM, see here - http://www.tokutek.com/2011/09/write-optimization-myths-comp...