RDBMS to NoSQL: Reviewing Some Next-Generation Non-Relational Database's

s In the world of cloud computing, one essential ingredient is a database that can accommodate a very large number of users on an ondemand basis. Distributed storage mechanisms are becoming the de-facto method of data storage for the new generation of web applications used by companies like Google, Amazon, Facebook, Twitter, Salesforce.com, Linkedin.com and Yahoo! etc., which are processing large amount of data at a petabyte scale. The main limitations with RDBMS are it is hard to scale with Data warehousing, Grid, Web 2.0 and Cloud applications, non-linear query execution time, unstable query plans and static schema. Even though RDBMS have provided database users with the best mix of simplicity, robustness, flexibility, performance, scalability and compatibility still next generation NoSQL ( not only SQL ) databases mostly being non-relational, distributed, open-source and horizontally scalable. The main characteristics of these databases are schema-free, no join, non-relational, easy replication support, simple API and eventually consistent. The aim of this paper is to provide a better understand of the nonrelational database design, architecture and comparison between them and also identify important research directions in this increasingly