Nodes Of XML Tree Research Articles

CBSL − A Compressed Binary String Labeling Scheme for Dynamic Update of XML Documents

The growing volume of XML documents over the Web has increased the need for an efficient mechanism to facilitate query processing. Many labeling schemes have been introduced to optimize data retrieval and query processing on XML database documents. As it is known, labels hold information about XML tree nodes such as their position, their relationship with other nodes and their order, which helps in query processing. Most of the existing labeling schemes support query processing over static XML documents. However, they need to re-label during dynamic update. In this paper a compressed binary string labeling scheme is proposed which supports dynamic update of XML documents without re-labeling existing nodes. Analytical results show that the proposed labeling scheme takes less label size in comparison with other labeling schemes. Also, an experiment has been conducted to evaluate the label generation time as well as update processing.

XPath fragments on XML in columns

Purpose – This paper considers schemaless XML data stored in a column-oriented storage, particularly in C-store. Axes of the XPath language are studied and a design and analysis of algorithms for processing the XPath fragment XP{*, //, /} are described in detail. The paper aims to discuss these issues. Design/methodology/approach – A two-level model of C-store based on XML-enabled relational databases is supposed. The axes of XPath language in this environment have been studied by Cástková and Pokorný. The associated algorithms have been used for the implementation of the XPath fragment XP{*, //, /}. Findings – The main advantage of this approach is algorithms implementing axes evaluations that are mostly of logarithmic complexity in n, where n is the number of nodes of XML tree associated with an XML document. A low-level memory system enables the estimation of the number of two abstract operations providing an interface to an external memory. The algorithms developed are mostly of logarithmic complexity in n, where n is the number of nodes of XML tree associated with an XML document. Originality/value – The paper extends the approach of querying XML data stored in a column-oriented storage to the XPath fragment using only child and descendant axes and estimates the complexity of evaluating its queries.

Automated Ranking of Relaxing Query Results Based on XML Structure and Content Preferences

This paper proposes a contextual preference query method of XML structural relaxation and content scoring to resolve the problem of empty or too many answers returned by XML. This paper proposes a XML contextual preference (XCP) model, where all the possible relaxing queries are determined by the users’ preferences. The XCP model allows users to express their interests on XML tree nodes, and then users assign interest scores to their interesting nodes for providing the best answers. A preference query results ranking method is proposed based on the XCP model, which includes: a Clusters_Merging algorithm to merge clusters based on the similarity of the context states, a Finding_Orders algorithm to find representative orders of the clusters, and a Top-k ranking algorithm to deal with the many answers problem. Results of preliminary user studies demonstrate that the method can provide users with most relevant and ranked query results. The efficiency and effectiveness of the approach are also demonstrated by experimental results.

PSN: A Dynamic Numbering Scheme for W3C XQuery Update Facility

It is essential to maintain hierarchical information properly for efficient XML query processing. Well known approach to represent hierarchical information of XML tree is assigning a specific node number to each node of XML tree. Insertion and deletion of XML node can occur at any position in a dynamic XML tree. A dynamic numbering scheme allows us to add nodes to or delete nodes from an XML tree without relabeling or with relabeling only a few existing nodes of XML tree while executing XML query efficiently. According to W3C XQuery update facility specifications a node can be added as first or last child of the existing node in XML tree. Generating new number for last child requires referencing the number of previous last child. Getting the number of last child is very costly with previous approaches. We have developed a new dynamic numbering scheme PSN which is very effective for insertion of a node as last child. Our approach reduces the time to find last child dramatically by removing sorting of children.

HiSC: A hybrid XML index composing structure-encoded with cluster

A new way of indexing and processing twig patterns in an XML documents is proposed in this paper. Every path in XML document can be transformed into a sequence of labels by Structure-Encoded that constructs a one-to-one correspondence between XML tree and sequence. Base on identifying characteristics of nodes in XML tree, the elements are classified and clustered. During query proceeding, the twig pattern is also transformed into its Structure-Encoded. By performing subsequence matching on the set of sequences in XML documents, all the occurrences of path in the XML documents are refined. Using the index, the numbers of elements retrieved are minimized. The search results with pertinent format provide more structure information without any false dismissals or false alarms. The index also supports keyword search. Experiment results indicate the index has significantly efficiency with high precision.

Layered Solution for SLCA Problem in XML Information Retrieval

SLCA (smallest lowest common ancestor) problem is a basic task of keyword search in XML information retrieval. It means to find all the nodes corresponding to the tightest subtrees in XML data, which involves the given keywords. Xu, et al., illustrate three algorithms—Indexed lookup eager (ILE), stack algorithm and scan eager (SE), and manifest that ILE has the best performance. Different from the complicated-B+-tree-based ILE algorithm, this paper proposes a layered solution for SLCA problem, named as LISA (layered intersection scan algorithm). It benefits from the distribution rule of SLCA nodes in XML tree, and calculates the SLCA nodes level by level (the deepest level runs first). That is, based on the retrieved Dewey codes corresponding to given keywords, the Dewey codes of SLCA nodes can be gotten by intersecting the prefix Dewey codes of each level. Compared with the ILE algorithm, LISA solutions need not sophisticated data structures, and have comparatively runtime performance. There are two instances following the LISA idea, called LISA I and LISA II respectively. They are distinguished from each other according to whether keeping Dewey codes in computation or transforming Dewey codes into integer sequences. Extensive experiments evaluate the performance of algorithms and prove the efficiency of LISA II.