Provided by: University of Pitesti
Topic: Big Data
Date Added: Aug 2013
Although the declarative nature of SQL provides great utility to database users, its use in distributed database management systems can leave users unaware of which servers in the system are evaluating portions of their queries. By allowing users to merely say what data they are interested in accessing without providing guidance regarding how to retrieve it, query optimizers can generate plans with unintended consequences to the user (e.g., violating user privacy by revealing sensitive portions of a user's query to untrusted servers, or impacting result freshness by pulling data from stale data stores).