Proceedings of ISP RAS


An Overwiew of Evolution of Lexical Query Optimization Techniques.

Mendkovich N.A., Kuznetcov S.D.

Abstract

The presented overview is concerned with lexical query optimization and covers papers published in the last four decades. The paper consists of five sections. The first section – Introduction – classifies query optimization techniques into semantic optimizations and lexical optimizations. Semantic optimizations usually relies on data integrity rules that are stores within metadata part of databases, and on data statistics. This kind of optimizations is discussed in many textbooks and papers. Lexical optimizations (more often called rewriting) use only a text of query and no other information about database and its structure. Lexical optimizations are further classified into query transformations, query amelioration, and query reduction. The second section of the paper discusses techniques of query transformation such as predicate pushdown, transformation of nested query into query with joins, etc. Query amelioration is a topic of the third section with a focus on magic set optimizations. The forth section covers query reduction optimizations. The section briefly describes traditional approaches (such as tableau-based) and considers in more details three new algorithms proposed by authors. The fifth section concludes the paper.

Keywords

query optimization; query simplification; lexical query optimization; magic sets

Edition

Proceedings of the Institute for System Programming, vol. 23, 2012, pp. 195-214.

ISSN 2220-6426 (Online), ISSN 2079-8156 (Print).

DOI: 10.15514/ISPRAS-2012-23-12

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