MonetDB/XQuery: A Fast XQuery Processor Powered by a Relational Engine. In (2006)

by Peter Boncz, Torsten Grust, Maurice van Keulen, Stefan Manegold, Jan Rittinger, Jens Teubner
Venue:Proc. SIGMOD,
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ESTER: efficient search on text, entities, and relations

by Holger Bast, Alexandru Chitea, Fabian Suchanek, Ingmar Weber , 2007
"... We present ESTER, a modular and highly efficient system for combined full-text and ontology search. ESTER builds on a query engine that supports two basic operations: prefix search and join. Both of these can be implemented very efficiently with a compact index, yet in combination provide powerful q ..."
Abstract - Cited by 51 (4 self) - Add to MetaCart
We present ESTER, a modular and highly efficient system for combined full-text and ontology search. ESTER builds on a query engine that supports two basic operations: prefix search and join. Both of these can be implemented very efficiently with a compact index, yet in combination provide powerful querying capabilities. We show how ESTER can answer basic SPARQL graphpattern queries on the ontology by reducing them to a small number of these two basic operations. ESTER further supports a natural blend of such semantic queries with ordinary full-text queries. Moreover, the prefix search operation allows for a fully interactive and proactive user interface, which after every keystroke suggests to the user possible semantic interpretations of his or her query, and speculatively executes the most likely of these interpretations. As a proof of concept, we applied ESTER to the English Wikipedia, which contains about 3 million documents, combined with the recent YAGO ontology, which contains about 2.5 million facts. For a variety of complex queries, ESTER achieves worst-case query processing times of a fraction of a second, on a single machine, with an index size of about 4 GB.

Pftijah: text search in an xml database system

by Djoerd Hiemstra, Henning Rode, Roel Van Os, Jan Flokstra - In Proceedings of the 2nd International Workshop on Open Source Information Retrieval (OSIR , 2006
"... This paper introduces the PF/Tijah system, a text search system that is integrated with an XML/XQuery database management system. We present examples of its use, we explain some of the system internals, and discuss plans for future work. PF/Tijah is part of the open source release of MonetDB/XQuery. ..."
Abstract - Cited by 38 (20 self) - Add to MetaCart
This paper introduces the PF/Tijah system, a text search system that is integrated with an XML/XQuery database management system. We present examples of its use, we explain some of the system internals, and discuss plans for future work. PF/Tijah is part of the open source release of MonetDB/XQuery.
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Database Architecture Evolution: Mammals Flourished long before Dinosaurs became Extinct

by Stefan Manegold, Martin L. Kersten, Peter Boncz
"... The holy grail for database architecture research is to find a solution that is Scalable & Speedy, to run on anything from small ARM processors up to globally distributed compute clusters, Stable & Secure, to service a broad user community, Small & Simple, to be comprehensible to a small ..."
Abstract - Cited by 33 (9 self) - Add to MetaCart
The holy grail for database architecture research is to find a solution that is Scalable & Speedy, to run on anything from small ARM processors up to globally distributed compute clusters, Stable & Secure, to service a broad user community, Small & Simple, to be comprehensible to a small team of programmers, Self-managing, to let it run out-of-the-box without hassle. In this paper, we provide a trip report on this quest, covering both past experiences, ongoing research on hardware-conscious algorithms, and novel ways towards self-management specifically focused on column store solutions. 1.
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MonetDB: Two Decades of Research in Column-Oriented Database Architectures

by Author(s S. Idreos, F. Groffen, N. Nes, S. Manegold, S. Mullender, M. Kersten, Stratos Idreos, Fabian Groffen, Niels Nes, Stefan Manegold, Sjoerd Mullender, Martin Kersten - IEEE Data Eng. Bull
"... Copyright It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content licence (like ..."
Abstract - Cited by 31 (1 self) - Add to MetaCart
Copyright It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content licence (like
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Structured Materialized Views for XML Queries

by Andrei Arion, et al. , 2007
"... The performance of XML database queries can be greatly enhanced by rewriting them using materialized views. We study the problem of rewriting a query using materialized views, where both the query and the views are described by a tree pattern language, appropriately extended to capture a large XQuer ..."
Abstract - Cited by 29 (7 self) - Add to MetaCart
The performance of XML database queries can be greatly enhanced by rewriting them using materialized views. We study the problem of rewriting a query using materialized views, where both the query and the views are described by a tree pattern language, appropriately extended to capture a large XQuery subset. The pattern language features optional nodes and nesting, allowing to capture the data needs of nested XQueries. The language also allows describing storage features such as structural identifiers, which enlarge the space of rewritings. We study pattern containment and equivalent rewriting under the constraints expressed in a structural summary, whose enhanced form also entails integrity constraints. Our approach is implemented in the ULoad [6] prototype and we present a performance analysis.

XRPC: Interoperable and Efficient Distributed XQuery

by Ying Zhang - In VLDB , 2007
"... We propose XRPC, a minimal XQuery extension that enables distributed yet efficient querying of heterogeneous XQuery data sources. XRPC enhances the existing concept of XQuery functions with the Remote Procedure Call (RPC) paradigm. By calling out of an XQueryfor-loop to multiple destinations, and by ..."
Abstract - Cited by 24 (5 self) - Add to MetaCart
We propose XRPC, a minimal XQuery extension that enables distributed yet efficient querying of heterogeneous XQuery data sources. XRPC enhances the existing concept of XQuery functions with the Remote Procedure Call (RPC) paradigm. By calling out of an XQueryfor-loop to multiple destinations, and by calling functions that themselves perform XRPC calls, complex P2P communication patterns can be achieved. The XRPC extension is orthogonal to all XQuery features, including the XQuery Update Facility (XQUF). We provide formal semantics for XRPC that encompasses execution of both read-only and update queries. XRPC is also a network SOAP sub-protocol, that integrates seamlessly with web services and Service Oriented Architectures (SOA), and AJAX-based GUIs. A crucial feature of the protocol is bulk RPC, that allows remote execution of many different calls to the same procedure, using possibly a single network round-trip. The efficiency potential of XRPC is demonstrated via an open-source implementation in MonetDB/XQuery. We show, however, that XRPC is not system-specific: every XQuery data source can service XRPC calls using a wrapper. Since XQuery is a pure functional language, we can leverage techniques developed for functional query decomposition to rewrite data shipping queries into XRPC-based function shipping queries. Powerful distributed database techniques (such as semi-join optimizations) directly map on bulk RPC, opening up interesting future work opportunities. 1.
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Why Off-the-Shelf RDBMSs are Better at XPath Than You Might Expect

by Torsten Grust, Jan Rittinger, Jens Teubner , 2007
"... To compensate for the inherent impedance mismatch between the relational data model (tables of tuples) and XML (ordered, unranked trees), tree join algorithms have become the prevalent means to process XML data in relational databases, most notably the TwigStack [6], structural join [1], and stairca ..."
Abstract - Cited by 24 (3 self) - Add to MetaCart
To compensate for the inherent impedance mismatch between the relational data model (tables of tuples) and XML (ordered, unranked trees), tree join algorithms have become the prevalent means to process XML data in relational databases, most notably the TwigStack [6], structural join [1], and staircase join [13] algorithms. However, the addition of these algorithms to existing systems depends on a significant invasion of the underlying database kernel, an option intolerable for most database vendors. Here, we demonstrate that we can achieve comparable XPath performance without touching the heart of the system. We carefully exploit existing database functionality and accelerate XPath navigation by purely relational means: partitioned B-trees bring access costs to secondary storage to a minimum, while aggregation functions avoid an expensive computation and removal of duplicate result nodes to comply with the XPath semantics. Experiments carried out on IBM DB2 confirm that our approach can turn off-the-shelf database systems into efficient XPath processors.
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A SQL:1999 Code Generator for the Pathfinder XQuery Compiler

by Torsten Grust, Manuel Mayr, Jan Rittinger, Sherif Sakr, Jens Teubner - IN PROC. SIGMOD , 2007
"... The Pathfinder XQuery compiler has been enhanced by a new code generator that can target any SQL:1999-compliant relational database system (RDBMS). This code generator marks an important next step towards truly relational XQuery processing, a branch of database technology that aims to turn RDBMSs in ..."
Abstract - Cited by 15 (10 self) - Add to MetaCart
The Pathfinder XQuery compiler has been enhanced by a new code generator that can target any SQL:1999-compliant relational database system (RDBMS). This code generator marks an important next step towards truly relational XQuery processing, a branch of database technology that aims to turn RDBMSs into highly efficient XML and XQuery processors without the need to invade the relational database kernel. Pathfinder, a retargetable front-end compiler, translates input XQuery expressions into DAG-shaped relational algebra plans. The code generator then turns these plans into sequences of either SQL:1999 statements or view definitions which jointly implement the (sometimes intricate) XQuery semantics. In a sense, this demonstration thus lets relational algebra and SQL swap their traditional roles in database query processing. The result is a code generator that (1) supports an almost complete dialect of XQuery, (2) can target any RDBMS with a SQL:1999 language interface, and (3) exhibits quite promising performance characteristics when run against high-volume XML data as well as complex XQuery expressions.

eXrQuy: Order Indifference in XQuery

by Torsten Grust, Jan Rittinger, Jens Teubner - IN PROC. OF THE 23TH INT’L CONFERENCE ON DATA ENGINEERING (ICDE , 2007
"... There are more spots than immediately obvious in XQuery expressions where order is immaterial for evaluation— this affects most notably, but not exclusively, expressions in the scope of unordered { } and the argument of fn:unordered (). Clearly, performance gains are lurking behind such expression c ..."
Abstract - Cited by 14 (7 self) - Add to MetaCart
There are more spots than immediately obvious in XQuery expressions where order is immaterial for evaluation— this affects most notably, but not exclusively, expressions in the scope of unordered { } and the argument of fn:unordered (). Clearly, performance gains are lurking behind such expression contexts but the prevalent impact of order on the XQuery semantics reaches deep into any compliant XQuery processor, making it non-trivial to set this potential free. Here, we describe how the relational XQuery compiler Pathfinder uniformly exploits such order indifference in a purely algebraic fashion: Pathfinder-emitted plans faithfully implement the required XQuery order semantics but (locally) ignore order wherever this is admitted.
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XCheck: a platform for benchmarking XQuery engines

by L. Afanasiev, M. Franceschet, M. Marx, E. Zimuel - In Proceedings of the 32nd International Conference on Very Large Data Bases , 2006
"... XCheck is a tool for assessing the relative per-formance of different XQuery/XPath engines by means of benchmarks consisting of a set of XML queries and a set of XML documents. Given a benchmark and a set of engines, XCheck runs the benchmark on these engines and produces highly informative performa ..."
Abstract - Cited by 14 (6 self) - Add to MetaCart
XCheck is a tool for assessing the relative per-formance of different XQuery/XPath engines by means of benchmarks consisting of a set of XML queries and a set of XML documents. Given a benchmark and a set of engines, XCheck runs the benchmark on these engines and produces highly informative performance output. The cur-rent version of XCheck contains the most popular XQuery and XPath benchmarks and the following
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