Optimization of nested SQL queries revisited
Current methods of evaluating nested queries in the SQL Language can be inefficient in a variety of query and data base contexts. Previous research in the area of nested query optimization which sought methods of reducing evaluation costs is summarized, including a classification scheme for nested queries, algorithms designed to transform each type of query to a logically equivalent form which may then be evaluated more efficiently, and a description of a major bug in one of these algorithms. Further examination reveals another bug in the same algorithm. Solutions to these bugs are proposed and incorporated into a new transformation algorithm, and extensions are proposed which will allow the transformation algorithms to handle a larger class of predicates. A recursive algorithm for processing a general nested query is presented and the action of this algorithm is demonstrated. This algorithm can be used to transform any nested query.
- Research Organization:
- Lawrence Berkeley Lab., CA (USA); San Francisco State Univ., CA (USA). Dept. of Computer Science
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 6470730
- Report Number(s):
- LBL-22396; CONF-8705107-1; ON: DE87010262
- Country of Publication:
- United States
- Language:
- English
Similar Records
Optimization of recursive data-base query languages
The SQL Query Used to Generate the Report