Harsha Raja, Master of Engineering

Supervisor: Dr. Pavle Mogin
Research: Referential Integrity constraints in Cloud NoSQL Databases

Contact Information

Harsha Raja
Phone: +64 4 463 5233 x8486
Mobile: +64 22 672 8196
Email: Harsha.Subramania.Raja@ecs.vuw.ac.nz
Office: CO251, Cotton Building, Kelburn Campus-Postal address


Cloud Computing, Database Architectures, DBMS Administration, Object Oriented Programming, Project Management, Software Development


Cloud computing delivers on-demand access to essential computing services providing benefits such as reduced maintenance, lower costs, global access, and others. One of its important and prominent services is DaaS which includes cloud DBMS. Cloud DBMS commonly adopt the key-value data model and are called Not Only SQL (NoSQL)DBMS. These provide cloud suitable features like scalability, flexibility and robustness, but in order to provide these, features such as referential integrity are often sacrificed. In such cases, referential integrity is left to be dealt with by the applications instead of being handled by the cloud DBMS. Thus, applications are required to either deal with inconsistency in the data (e.g. dangling references) or to incorporate the necessary logic to ensure that referential integrity is maintained.

My research presents an API that serves as a middle layer between the applications and the cloud DBMS in order to maintain referential integrity. The API provides the necessary Create, Read, Update, Delete (CRUD) operations to be performed on the DBMS while ensuring that the referential integrity constraints are satisfied. These constraints are represented as metadata and four different approaches are provided to store it. Furthermore, the performance of these approaches is measured with different referential integrity constraints and evaluated upon a set of experiments in Apache Cassandra, a prominent cloud NoSQL DBMS. The results showed significant differences between the approaches in terms of performance. However, the final word on which one is better depends on the application demands as each approach presents different trade-offs.

Open Source Projects

Referential Integrity API
Referential Integrity in Cloud NoSQL Databases (specifically, in Apache Cassandra)