Extensible/rule based query rewrite optimization in Starburst
SIGMOD '92 Proceedings of the 1992 ACM SIGMOD international conference on Management of data
Holistic twig joins: optimal XML pattern matching
Proceedings of the 2002 ACM SIGMOD international conference on Management of data
DataGuides: Enabling Query Formulation and Optimization in Semistructured Databases
VLDB '97 Proceedings of the 23rd International Conference on Very Large Data Bases
VLDB '99 Proceedings of the 25th International Conference on Very Large Data Bases
DBPL '01 Revised Papers from the 8th International Workshop on Database Programming Languages
ViST: a dynamic index method for querying XML data by tree structures
Proceedings of the 2003 ACM SIGMOD international conference on Management of data
Structural Joins: A Primitive for Efficient XML Query Pattern Matching
ICDE '02 Proceedings of the 18th International Conference on Data Engineering
Tree logical classes for efficient evaluation of XQuery
SIGMOD '04 Proceedings of the 2004 ACM SIGMOD international conference on Management of data
Full-Fledged Algebraic XPath Processing in Natix
ICDE '05 Proceedings of the 21st International Conference on Data Engineering
A Complete and Efficient Algebraic Compiler for XQuery
ICDE '06 Proceedings of the 22nd International Conference on Data Engineering
An efficient infrastructure for native transactional XML processing
Data & Knowledge Engineering
From tree patterns to generalized tree patterns: on efficient evaluation of XQuery
VLDB '03 Proceedings of the 29th international conference on Very large data bases - Volume 29
Hash-based structural join algorithms
EDBT'06 Proceedings of the 2006 international conference on Current Trends in Database Technology
Using Structural Joins and Holistic Twig Joins for Native XML Query Optimization
ADBIS '09 Proceedings of the 13th East European Conference on Advances in Databases and Information Systems
An integrative approach to query optimization in native XML database management systems
Proceedings of the Fourteenth International Database Engineering & Applications Symposium
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In recent years, the database community has seen many sophisticated Structural Join and Holistic Twig Join algorithms as well as several index structures supporting the evaluation of twig query patterns. Even though almost all XML query evaluation proposals in the literature use one of those evaluation methods, we believe that (1) there is no internal representation that enables a smooth transition between the XQuery language level and physical algebra operators, and (2) there is still no approach that considers the combination of content-and-structure indexes, Structural Join (SJ), and Holistic Twig Join (HTJ) algorithms to speed up the evaluation of twig queries. To overcome this deficit, we propose an enhancement to Starburst's Query Graph Model as an internal representation for XML query languages such as XQuery. This representation permits the usage of SJ and HTJ operators as part of the logical algebra. For twig queries, we define a set of rewrite rules which initiate query graph transformations towards improved processability, e.g., to fuse adjacent binary join operators to an n-way join operator. To enhance the evaluation flexibility of twig queries, we come up with further rewrite rules to prepare query graphs---even before query transformation---for making the most of existing joins and indexes.