Processing Operations with Restrictions in RDBMS without External Sorting: The Tetris Algorithm

Most operations of the relational algebra or SQL require a sorted stream of tuples for efficient processing. Therefore, processing complex relational queries relies on efficient access to a table in some sort order. In principle, indexes could be used, but they are superior to a full table scan only, if the result set is sufficiently restricted in the index attribute. In this paper we present the Tetris algorithm, which utilizes restrictions to process a table in sort order of any attribute without the need of external sorting. The algorithm relies on the space partitioning of a multidimensional access method. A sweep line technique is used to read data in sort order of any attribute, while accessing each disk page of a table only once. Results are produced earlier than with traditional sorting techniques, allowing better response times for interactive applications and pipelined processing of the result set. We describe a prototype implementation of the Tetris algorithm using UB-Trees...

• Type: Conference
• Year: 1999
• Where: ICDE
• Authors: Volker Markl, Martin Zirkel, Rudolf Bayer
• Keywords: Complex Relational Queries, Database, ICDE 1999, Sort Order, Tetris Algorithm