For example, you could query to find and extract all records that contained sales greater $1000 but less than $5000—but only on flat files (only one database matrix).

A question asked about data contained in two or more tables in a relational database. The relational query must specify the tables required and what the condition is that links them; for example ...

At the crux of many an enterprise-scale big data system stands either MapReduce or a parallel database management system. But which is more efficient? Researchers from Dublin Institute of Technology, ...