MongoDB doesn’t need multi-statement transactions. Both are limited by 1-writer or N-reader concurrency, but writes to database files are much faster with LevelDB because it doesn’t do update in place. So LevelDB doesn’t lose as much performance for IO-bound workloads by doing 1-writer or N-readers and my guess is that this could make MongoDB much better at supporting IO-bound workloads.
If getting LevelDB as a storage engine for MySQL is doubtful and I wouldn’t hold my breath until MongoDB would be using it, keep in mind that Riak might actually use LevelDB at some point.
Update: Justin Sheehy (CTO, Basho) has kindly (again) corrected me: LevelDB is supported and ships with Riak since the release of Riak 1.0. Plus it is the backend for the new secondary indexes, as it was correctly mentioned in the comments by Philip Cristiano.
Original title and link: LevelDB Might Be a Great Fit for MongoDB ( ©myNoSQL)