With ArangoDB you can choose between synchronous replication and asynchronous. With the Agency of ArangoDB you also have a RAFT based consensus protocol which h

With ArangoDB you can choose between synchronous replication and asynchronous. With the Agency of ArangoDB you also have a RAFT based consensus protocol which holds the state of the cluster. My team mate wrote a nice article about our approach. You might want to have a look: https://www.arangodb.com/2017/01/reaching-harnessing-consensus-arangodb/ https://www.arangodb.com/2017/01/reaching-harnessing-consens.... In single instance you have full transactional guarantees with multi collection and multi document transactions. In cluster mode we provide single document transactions. More guarantees will follow.