Journey of Database Migration from RDBMS to NoSQL Data Stores

Migration is a complex process involving many challenges while migrating from an existing system to a new one. Database migration involves schema transformation, migration of data, complex query support, and indexing. This paper presents a) Journey on existing migration techniques from RDBMS (SQL) to NoSQL databases. Schema migration and Data migration are two main aspects while migrating from relational to NoSQL database. b) The various existing techniques related to schema migration and data migration. The techniques presented for schema migration include graph-based algorithms, denormalization techniques such as column level denormalization and table level denormalization, link list-based, and ETL tools. The paper also addresses different business methods for data migration, commonly known as basic tools and ETL tools. c) The authors highlight some open challenges like need and cost of denormalization and selection of columns for denormalization. The assessment of various techniques (based on space or time costs) is presented. The key challenge is to pick a particular datastore on which to apply a specific technique. d) The paper also describes current market-driven migration tools based on each particular data store. e) It also throws light on different organizations that successfully migrated to a particular NoSQL data store. Thus, the purpose of this study is to contribute to the state-of-the-art in the field of database migration and to serve as a foundation for selecting and developing RDBMS-to-NoSQL data migration techniques or tools.