Query optimization in a memory-resident domain relational calculus database system
ACM Transactions on Database Systems (TODS)
Extensible/rule based query rewrite optimization in Starburst
SIGMOD '92 Proceedings of the 1992 ACM SIGMOD international conference on Management of data
WWW '99 Proceedings of the eighth international conference on World Wide Web
On optimizing an SQL-like nested query
ACM Transactions on Database Systems (TODS)
Optimizing object queries using an effective calculus
ACM Transactions on Database Systems (TODS)
ICDE '96 Proceedings of the Twelfth International Conference on Data Engineering
Answering XML Queries on Heterogeneous Data Sources
Proceedings of the 27th International Conference on Very Large Data Bases
Minimization and Group-By Detection for Nested XQueries
ICDE '04 Proceedings of the 20th International Conference on Data Engineering
Nested Queries and Quantifiers in an Ordered Context
ICDE '04 Proceedings of the 20th International Conference on Data Engineering
Odysseus: A High-Performance ORDBMS Tightly-Coupled with IR Features
ICDE '05 Proceedings of the 21st International Conference on Data Engineering
ACM SIGMOD Record
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XQuery becomes a standard of the XML query language. Just like in SQL, XQuery allows nested expressions. To optimize XQuery processing, a lot of research has been done on normalization, i.e., transforming nested expressions to equivalent unnested ones. Previous normalization rules are classified into two categories – source-level and algebra-level – depending on whether a construct is specified by using a query language or an algebraic expression. In implementation point of view, we contend that the source-level rule is preferable to the algebra-level rule because algebras used for normalization are hard to be directly exploited in a typical DBMS. However, a complete set of source-level rules is yet to be developed. In this paper, we propose source-level rules for normalizing XQuery expressions and present an implementation mechanism. We show that our rules are correct and complete according to the nesting types classified by Kim. Our mechanism is easily implementable since it adapts the well-known Query Graph Model (QGM) representation. We have successfully implemented this mechanism into our XML DBMS named Odysseus/XML.