Title :
Nested queries and quantifiers in an ordered context
Author :
May, Norman ; Helmer, Sven ; Moerkotte, Guido
Author_Institution :
Mannheim Univ., Germany
Abstract :
We present algebraic equivalences that allow to unnest nested algebraic expressions for order-preserving algebraic operators. We illustrate how these equivalences can be applied successfully to unnest nested queries given in the XQuery language. Measurements illustrate the performance gains possible by unnesting.
Keywords :
equivalence classes; mathematical operators; query languages; query processing; XQuery language; algebraic equivalence; nested algebraic expression; nested quantifiers; nested queries; order-preserving algebraic operator; Aggregates; Algebra; Computer bugs; Data engineering; Database languages; Gain measurement; Object oriented databases; Performance gain; Relational databases; XML;
Conference_Titel :
Data Engineering, 2004. Proceedings. 20th International Conference on
Print_ISBN :
0-7695-2065-0
DOI :
10.1109/ICDE.2004.1320001
