2,127 research outputs found
Desirable properties for XML update mechanisms
The adoption of XML as the default data interchange format and the standardisation of the XPath and XQuery languages has resulted in significant research in the development and implementation of XML databases capable of processing queries efficiently. The ever-increasing deployment of XML in industry and the real-world requirement to support efficient updates to XML documents has more recently prompted research in dynamic XML labelling schemes. In this paper, we provide an overview of the recent research in dynamic XML labelling schemes. Our motivation is to define a set of properties that represent a more holistic dynamic labelling scheme and present our findings through an evaluation matrix for most of the existing schemes that provide update functionality
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Pentagonal scheme for dynamic XML prefix labelling
In XML databases, the indexing process is based on a labelling or
numbering scheme and generally used to label an XML document to
perform an XML query using the path node information. Moreover, a
labelling scheme helps to capture the structural relationships during the
processing of queries without the need to access the physical document.
Two of the main problems for labelling XML schemes are duplicated
labels and the cost efficiency of labelling time and size. This research
presents a novel dynamic XML labelling scheme, called the Pentagonal
labelling scheme, in which data are represented as ordered XML nodes
with relationships between them. The update of these nodes from large scale XML documents has been widely investigated and represents a
challenging research problem as it means relabelling a whole tree. Our
algorithms provide an efficient dynamic XML labelling scheme that
supports data updates without duplicating labels or relabelling old nodes.
Our work evaluates the labelling process in terms of size and time, and
evaluates the labelling scheme’s ability to handle several insertions in
XML documents. The findings indicate that the Pentagonal scheme
shows a better initial labelling time performance than the compared
schemes, particularly when using large XML datasets. Moreover, it
efficiently supports random skewed updates, has fast calculations and
uncomplicated implementations so efficiently handles updates. Also, it
proved its capability in terms of the query performance and in determining
the relationships.Libyan governmen
Labeling Workflow Views with Fine-Grained Dependencies
This paper considers the problem of efficiently answering reachability
queries over views of provenance graphs, derived from executions of workflows
that may include recursion. Such views include composite modules and model
fine-grained dependencies between module inputs and outputs. A novel
view-adaptive dynamic labeling scheme is developed for efficient query
evaluation, in which view specifications are labeled statically (i.e. as they
are created) and data items are labeled dynamically as they are produced during
a workflow execution. Although the combination of fine-grained dependencies and
recursive workflows entail, in general, long (linear-size) data labels, we show
that for a large natural class of workflows and views, labels are compact
(logarithmic-size) and reachability queries can be evaluated in constant time.
Experimental results demonstrate the benefit of this approach over the
state-of-the-art technique when applied for labeling multiple views.Comment: VLDB201
A relevance comparison between interval and prefix labelling schemes
Improving XML database management system has attracted researchers to consider whether the indexing system is equivalent to a relational database management system. The indexing system is based on labelling the nodes of the XML tree. Different types of labelling scheme have been proposed to label the document quickly and without consuming too much storage space. However, most the studies focused on evaluating the performance of new labelling schemes. The appropriateness of various existing schemes to the particular structure an XML document has not been addressed sufficiently. To investigate this aspect two common XML labelling schemes were employed: Prefix (Dewey Encoding) and Interval (Containment) to label three different examples of XML documents with very different structures. The time and storage space requirements were investigated to compare the relevance of each scheme to the structures of the documents. A number of experiments were conducted and it was found that Dewey Encoding and Containment techniques are relatively fast when labelling shallow tree structures. Dewey required little storage space to save labels of wide tree structures, however, Containment used less storage space when storing the labels of short trees
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