Deciding Distinctness of Query Results by Discovered Constraints (0)
| Venue: | Proc. of the 2nd International Conf. on the Practical Application of Constraint Technology |
| Citations: | 5 - 0 self |
BibTeX
@INPROCEEDINGS{Bell_decidingdistinctness,
author = {Siegfried Bell},
title = {Deciding Distinctness of Query Results by Discovered Constraints},
booktitle = {Proc. of the 2nd International Conf. on the Practical Application of Constraint Technology},
year = {},
pages = {399--417},
publisher = {Company Ltd}
}
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Abstract
The aim of query optimization is to produce an equivalent query which is less expensive to process than the original query. Semantic query optimization involves the use of semantic knowledge during the optimization process. The success strongly depends on the availability of this knowledge. We present a rule--based approach of semantic query optimization which overcomes the limitation of predefined knowledge by discovering constraints. We show that unnecessary distinct--keywords and group by--parts of an SQL query can be detected and removed with the use of discovered constraints. 1 Introduction Semantic query optimization (SQO) provides the same kind of transparency with respect to semantic knowledge like relational optimizers do with respect to physical representation. Since semantically equivalent queries can differ significantly in their evaluation costs, it is our major goal to free the user from finding the most effective query. Finding semantically equivalent queries requires s...
