Relational Database Management Systems (RDBMS) are designed to manage well-structured data, requiring users to design a schema before storing and querying data with the help of SQL (Structured Query Language). The evolution of database management system undergoes many developments for more than forty years to meet the challenges by modern applications. In this fast Growing science and technological period, where advancements in web technology, mobile devices and sensors (IoT) need to accommodate huge amount of structured and unstructured data, called Big Data. The demand for technologies with large processing and storage requirements are rising enormously. Customized RDBMS has to confront challenges against Big Data’s scalability and performances. To meet these requirements such as volume, variety, velocity and variability, enterprises are adopting alternative technologies like NoSQL and NewSQL. Currently, NewSQL scalability is classified as modern RDBMS which carries NoSQL for OLTP (Online Transaction Processing)   to read as well write data, whereas satisfying the Atomicity, Consistency, Isolation, and Durability (ACID) properties of a traditional DB system. Further my research paper introduces NoSQL and its key attributes and NewSQL (NuoDB, VoltDB)