These days, the major challenge for database organizations worldwide is efficient and fast data access and processing. The present relational model is good for vertical scaling but is insufficient to meet the big data requirements. So horizontal scalability is required to meet the challenges. This leads to the emergence of non-relational database models commonly known as NoSQL databases. One another major challenge of non-relational is the consistency issues due to the nonfulfillment of transactional support. Thus Consistency is the major challenge of in NoSQL databases that need to be reviewed further. In this paper, the various models of the NoSQL databases are analyzed in terms of key distribution parameters. Comparisons have been made for finding out the best NoSQL types and their models that can be used for particular parameters based on the scenario.

NoSQL, RDBMS, Consistency, transaction, CAP.