Couchbase database was a key-value store till sometime back. With the introduction of version 2.0 it has become a document oriented database. Now it has added support for JSON documents, indexing and querying, incremental map reduce and cross datacenter replication. The 2.0 release adds several new features making it easier for you to build richer and more powerful apps that
suit many different use-cases including content and metadata management systems, social and mobile games, ad targeting platforms, user profiles stores, application session stores, chat and messaging platforms or high availability caches.
As a NoSQL document database, with Couchbase, there’s no need to create and manage schemas. This greatly reduces the complexity and the time required to make changes to applications. Using documents, you can model your data exactly as it’s represented in the application, as objects and entities. Plus, document lookups are fast as all related data is located together.
In 2.0, it has added cross datacenter replication that allows you to replicate data from one cluster to the other so that your database is always on 24×365. It provides you with an easy way to replicate active data unidirectionally or bidirectionally to multiple datacenters across different geographical areas either for disaster recovery or to bring your data closer to your end users for reduced latencies. XDCR (Cross data center replication) and intra-cluster replication occur simultaneously.
Try Couchbase. It’s scalability is awesome.