One-unambiguous regular languages
Information and Computation
Automata and Computability
Foundations of Databases: The Logical Level
Foundations of Databases: The Logical Level
ToXgene: a template-based data generator for XML
Proceedings of the 2002 ACM SIGMOD international conference on Management of data
XPath queries on streaming data
Proceedings of the 2003 ACM SIGMOD international conference on Management of data
Processing XML streams with deterministic automata and stream indexes
ACM Transactions on Database Systems (TODS)
ViteX: A Streaming XPath Processing System
ICDE '05 Proceedings of the 21st International Conference on Data Engineering
Efficient evaluation of XQuery over streaming data
VLDB '05 Proceedings of the 31st international conference on Very large data bases
Semantic query optimization for XQuery over XML streams
VLDB '05 Proceedings of the 31st international conference on Very large data bases
An Efficient XPath Query Processor for XML Streams
ICDE '06 Proceedings of the 22nd International Conference on Data Engineering
VLDB '06 Proceedings of the 32nd international conference on Very large data bases
R-SOX: runtime semantic query optimization over XML streams
VLDB '06 Proceedings of the 32nd international conference on Very large data bases
Automaton meets algebra: a hybrid paradigm for XML stream processing
Data & Knowledge Engineering - Special issue: ER 2003
A transducer-based XML query processor
VLDB '02 Proceedings of the 28th international conference on Very Large Data Bases
XMark: a benchmark for XML data management
VLDB '02 Proceedings of the 28th international conference on Very Large Data Bases
VLDB '03 Proceedings of the 29th international conference on Very large data bases - Volume 29
Query processing for high-volume XML message brokering
VLDB '03 Proceedings of the 29th international conference on Very large data bases - Volume 29
VLDB '04 Proceedings of the Thirtieth international conference on Very large data bases - Volume 30
Efficiently loading and processing XML streams
IDEAS '08 Proceedings of the 2008 international symposium on Database engineering & applications
Constraint-Aware XSLT Evaluation
ER '08 Proceedings of the 27th International Conference on Conceptual Modeling
Hi-index | 0.01 |
XQuery evaluation over XML streams requires the temporary buffering of XML elements. This paper presents a semantic query optimization solution to minimize memory footprint during XQuery evaluation by exploiting schema knowledge. We focus on one particular class of constraints, namely, the Pattern Non-Occurrence (PNO) constraints for XML streams conforming to pre-defined DTDs. PNO constraints facilitate the early release of buffered data (early buffer release) or possibly avoid to ever store the data (buffer avoidance), thus achieving a minimized memory footprint. We develop an automaton-based technique to detect PNO constraints at runtime. For a given query, optimization opportunities of early buffer release and buffer avoidance which can be triggered by runtime PNO detection are explored and the optimization decision is then encoded into the Raindrop algebraic plan. We implement our optimization technique within the Raindrop XQuery engine. Our experimental studies illustrate that the proposed techniques bring significant performance improvement in both memory and CPU usage with little overhead.