Implementing Sorting in Database Systems

Most commercial database systems do (or should) exploit many sorting techniques that are publicly known, but not readily available in the research literature. These techniques improve both sort performance on mod- ern computer systems and the ability to adapt gracefully to resource fluctuations in multiuser operations. This survey collects many of these techniques for easy reference by students, researchers, and product de- velopers. It covers in-memory sorting, disk-based external sorting, and considerations that apply specifically to sorting in database systems. Categories and Subject Descriptors: E.5 [Data]: Files—Sorting/searching; H.2.2 [Database Manage- ment Systems]: Access Methods; H.2.4 [Database Management]: Systems—Query processing; relational databases; H.3.2 [Information Storage and Retrieval]: Information Storage—File organization General Terms: Algorithms, Performance Additional Key Words and Phrases: Key normalization, key conditioning, compression, dynamic memory resource allocation, graceful degradation, nested iteration, asynchronous read-ahead, forecasting, index operations