The title is slightly misleading since they also include PostgreSQL, MySQL and Memcached in their tests. They conclude: * MongoDB and Tokyo Tyrant are useful n

The title is slightly misleading since they also include PostgreSQL, MySQL and Memcached in their tests. They conclude: * MongoDB and Tokyo Tyrant are useful now. CouchDB has promise, but is too slow currently. * Non-relational databases have shown their worth at larger sites when used cleverly. * Non-relational databases will continue to improve performance, stability & features. * Relational databases are still a great choice: fast, powerful and proven. With caching, denormalization, rework (e.g. Drizzle) & better replication, they will continue to be competitive.