Databases in a distributed system that appear to applications as a single data source.
- Apache Cassandra - Column-oriented and providing high availability with no single point of failure.
- Apache HBase - Hadoop database for big data.
- Druid - Real-time and historical OLAP data store that excel at aggregation and approximation queries.
- Infinispan - Highly concurrent key/value datastore used for caching.
- OpenTSDB - Scalable and distributed time series database written on top of Apache HBase.
- OrientDB - Embeddable distributed database written on top of Hazelcast.