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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
Compressing Labels of Dynamic XML Data using Base-9 Scheme and Fibonacci Encoding
The flexibility and self-describing nature of XML has made it the most common mark-up language used for data representation over the Web. XML data is naturally modelled as a tree, where the structural tree information can be encoded into labels via XML labelling scheme in order to permit answers to queries without the need to access original XML files. As the transmission of XML data over the Internet has become vibrant, it has also become necessary to have an XML labelling scheme that supports dynamic XML data. For a large-scale and frequently updated XML document, existing dynamic XML labelling schemes still suffer from high growth rates in terms of their label size, which can result in overflow problems and/or ambiguous data/query retrievals.
This thesis considers the compression of XML labels. A novel XML labelling scheme, named “Base-9”, has been developed to generate labels that are as compact as possible and yet provide efficient support for queries to both static and dynamic XML data. A Fibonacci prefix-encoding method has been used for the first time to store Base-9’s XML labels in a compressed format, with the intention of minimising the storage space without degrading XML querying performance. The thesis also investigates the compression of XML labels using various existing prefix-encoding methods. This investigation has resulted in the proposal of a novel prefix-encoding method named “Elias-Fibonacci of order 3”, which has achieved the fastest encoding time of all prefix-encoding methods studied in this thesis, whereas Fibonacci encoding was found to require the minimum storage.
Unlike current XML labelling schemes, the new Base-9 labelling scheme ensures the generation of short labels even after large, frequent, skewed insertions. The advantages of such short labels as those generated by the combination of applying the Base-9 scheme and the use of Fibonacci encoding in terms of storing, updating, retrieving and querying XML data are supported by the experimental results reported herein