Robust Query Processing in Database Systems*

Abstract

Database management systems constitute the backbone of today’s information-rich society, providing a congenial environment for handling enterprise data during its entire life cycle of generation, storage, maintenance and processing. The defacto standard user interface to query the information present in the database is SQL (Structured Query Language). An organic USP of SQL is its declarative persona, which enables users to focus solely on query formulation, leaving it to the database system to identify an efficient execution strategy. Paradoxically, however, the declarative constitution of SQL is also its Achilles heel. This is because the execution strategies chosen by the system often turn out, in hindsight, to be highly sub-optimal as compared to the ideal choice. Unfortunately, due to the intrinsic technical complexities and challenges, solutions to this long-standing problem have remained chronically elusive despite intensive study by the database research community over the past five decades.