Operational Databases carries out regular operations of an organisation and are generally very important to a business. They generally use online transaction processing that allows them to enter, collect and retrieve specific information about the company. It is optimized for faster processing of transactions (inserting, updating and deleting). Operational databases can store information like employee information, training status, etc and they work best when information is needed quickly.
VoltDB
VoltDB is an in-memory operational database that is based on NewSQL relational database that supports SQL access from within pre-compiled Java stored procedures. It is capable of writing and reading millions of data events per second and to serve large numbers of concurrent users. It has a modern distributed architecture with a scale out system in a shared-nothing configuration.
NUO DB
NuoDB is a distributed cloud database management system with a rich SQL implementation and true ACID transactions. It’s an operational DBMS designed to meet the needs of cloud-scale apps and the 50+ billion connected devices in use worldwide.