OrientDB - OrientDB - The World's First Distributed Multi-Model NoSQL Database with a Graph Database Engine.
Datomic - The fully transactional, cloud-ready, distributed database
PostgreSQL - PostgreSQL is a powerful, open source object-relational database system.
Datahike - A durable datalog database adaptable for distribution.
ArangoDB - A distributed open-source database with a flexible data model for documents, graphs, and key-values.
MarkLogic Server - MarkLogic Server is a multi-model database that has both NoSQL and trusted enterprise data management capabilities.