Despite all the excitement around big data, the large majority of mission-critical data is still stored in relational database management systems. This fact is supported by recent studies online and confirmed by my own professional experience working on numerous big data and business intelligence projects. Despite widespread interest in unstructured and semi-structured data, structured data still represents a significant percentage of data under management for most organizations, from the largest corporations and government agencies to small businesses and technology start-ups. Use cases that deals with unstructured and semi-structured data, while valuable and interesting, are few and far between. Unless you work for a company that does a lot of unstructured data processing such as Google, Facebook, or Apple, you are most likely working with structured data.
Quinto, B. (2018). Next-Generation Big Data. Next-Generation Big Data. Apress. https://doi.org/10.1007/978-1-4842-3147-0