On supporting containment queries in relational database management systems
SIGMOD '01 Proceedings of the 2001 ACM SIGMOD international conference on Management of data
XRel: a path-based approach to storage and retrieval of XML documents using relational databases
ACM Transactions on Internet Technology (TOIT)
APEX: an adaptive path index for XML data
Proceedings of the 2002 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
A Fast Index for Semistructured Data
Proceedings of the 27th International Conference on Very Large Data Bases
PathGuide: An Efficient Clustering Based Indexing Method for XML Path Expressions
DASFAA '03 Proceedings of the Eighth International Conference on Database Systems for Advanced Applications
Structural Joins: A Primitive for Efficient XML Query Pattern Matching
ICDE '02 Proceedings of the 18th International Conference on Data Engineering
BLAS: an efficient XPath processing system
SIGMOD '04 Proceedings of the 2004 ACM SIGMOD international conference on Management of data
Staircase join: teach a relational DBMS to watch its (axis) steps
VLDB '03 Proceedings of the 29th international conference on Very large data bases - Volume 29
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Efficient evaluation of queries on XML data is a major research issue. Structural join based techniques are well known for XPath evaluation. For the long path expressions, join techniques are not efficient as they increase the number of joins and disk I/O cost. Path based techniques try to reduce the number of joins. In this paper, we propose a metadata guided query evaluation technique which uses path based storage. We use interval encoding for the nodes. In addition, we use Strong DataGuide to assign integer path labels to distinct root-to-node label paths in the data tree. An element list is maintained for each distinct path consisting of nodes that can be reached by that path. The Element-Map gives the one-to-many mapping between element names (or tag names) to element lists with nodes having that tag-name. The Path-Map gives the root-to-leaf path for a given path label. Using these structures, we can combine top-down path matching and bottom-up path selections to efficiently evaluate linear path expressions. For twig queries, we perform structural joins at branch points. Through experimental evaluation on standard datasets, we show that our approach outperforms the existing path-index based approaches which in turn outperform structural join methods.