• Journal of KIISE:Databases
• /
• v.32 no.6
• /
• pp.641-649
• /
• 2005

As XML is widely used with the development of internet, many researches on the XML storage and query processing have been done Several index techniques have been proposed to efficiently process XML path queries. Recently, structural join has received murk attention as a method to protest the path query. Structural join technique process a path query by identifying the containment relationship of elements. Especially, it has an advantage that we can get the result set by simply comparing related elements only instead of scanning whole document. However during the comparison process, unnecessary elements that are not included in the result set can be scanned. So we propose a new technique, the level structural join. In this technique, we use both the relationship and the level distribution of elements in the path query. Using this technique, we tao improve the performance of query processing only by comparing elements with specific level in the target inverted level.

• The KIPS Transactions:PartD
• /
• v.9D no.5
• /
• pp.789-800
• /
• 2002

XML is a standard format of web data and is currently used as a prevailing language for exchanging data. Most of the commercial data are stored in a relational database. It is quite important to convert these conventionally stored data into those for exchange and use them in data exchange, or to get the query results effectively by utilizing XQL on XML data which are store in a relational database. Thus, it is absolutely required to have a proper query processing mechanism for XML data and to maintain many XML data properly. Up to now, many cases of researches on the storage and retrieval of XML data have been carried out and under study. But, effective retrieval and storage system for path queries like XQL has yet to be contrived. Thus, in this paper, a schema to store XML data is designed, in which DFS-Numbegering method is used to store data effectively. And an effective path query processing method is also designed and implemented, in which a traditional relational database engine is used. That is, XQL is converted into SQL with a XQL processor if a user makes query XQL in a system. A database system executes SQL, and a XML generator uses a generated record and makes a XML document.

• The KIPS Transactions:PartD
• /
• v.14D no.6
• /
• pp.605-614
• /
• 2007

As a standard query language to search XML data, XQuery and XPath were proposed by W3C. By widely using XQuery and XPath languages, recent researches focus on the development of query processing algorithm and data structure for efficiently processing XML query with the enormous XML database system. Recently, when processing XML path expressions, the concept of the structural join which may determine the structural relationship between XML elements, e.g., ancestor-descendant or parent-child, has been one of the dominant XPath processing mechanisms. However, structural joins which frequently occur in XPath query processing require high cost. In this paper, we propose a new structural join algorithm, called SISJ, based on our structured index, called SI, in order to process XPath queries efficiently. Experimental results show that our algorithm performs marginally better than previous ones. However, in the case of high recursive documents, it performed more than 30% by the pruning feature of the proposed method.

• The KIPS Transactions:PartD
• /
• v.13D no.1 s.104
• /
• pp.1-10
• /
• 2006

This paper introduces the development XPERT(XML Query Processing Engine using Relational Technologies) which is based on relational model. In our system we have used a decomposed approach to store XML files in relational tables. XML queries are translated to SQLs according to the table schema, and then they are sent to the relational DBMS to get the results back. Our translation scheme produces AST(Abstract Syntax Tree) by analyzing XQuery expressions at first. And on traversing AST proper SQLs are generated. Translated SQLs can reduce the number of joins by using path information and utilize dewey number to preserve document originated orderings among compoments in XML. In addition we propose the efficient algorithms of XPath and XQuery translation. And finally we show the implementation of our prototype system for the functional evaluations.

• Journal of KIISE:Databases
• /
• v.32 no.2
• /
• pp.193-203
• /
• 2005

XML (extensible Markup Language) is recognized as a standard of data representation and transmission on Internet. XPath is a standard for specifying parts of XML documents anda suitable language for both query processing and access control of XML. In this paper, we use the XPath expression for representing user queries and access control for XML. And we propose an access control method for XML, where we control accesses to XML documents by filtering query XPath expressions through access control XPath expressions. In the proposed method, we directly search XACT (XML Access Control Tree) for a query XPath expression and extract the access-granted parts. The XACT is our proposedstructure, where the edges are structural summary of XML elements and the nodes contain access-control information. We show the query XPath expressions are successfully filtered through the XACT by our proposed method, and also show the performance improvement by comparing the proposed method with the previous work.

• Journal of KIISE:Databases
• /
• v.32 no.3
• /
• pp.334-343
• /
• 2005

Complex queries such as path alld twig patterns have been the focus of much research on processing XML data. Structural join algorithms use a form of encoded structural information for elements in an XML document to facilitate join processing. Recently, structural join algorithms such as Twigstack and TSGeneric- have been developed to process such complex queries, and they have been shown that the processing costs of the algorithms are linearly proportional to the sum of input data. However, the algorithms have a shortcoming that their processing costs increase with the length of a queery. To overcome the shortcoming, we propose the segment join technique to augment the structural join with structural indexes such as the 1-Index. The SegmentTwig algorithm based on the segment join technique performs joins between a pair of segments, which is a series of query nodes, rather than joins between a pair of query nodes. Consequently, the query can be processed by reading only a query node per segment. Our experimental study shorts that segment join algorithms outperform the structural join methods consistently and considerably for various data sets.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.17 no.6
• /
• pp.766-772
• /
• 2007

As XML is widely used, many researches on the XML storage and query processing have been done. But, previous works on path query processing have mainly focused on the storage and retrieval methods for a large XML document or XML documents had a same DTD. Those researches did not efficiently process partial match queries on the differently-structured document set. To resolve the problem, we suggested a new index structure using relational table. The method constructs the $B^+$-tree index using backward label paths instead of forward label paths used in previous researches for storing path information and allows for finding the label paths that match the partial match queries efficiently using it when process the queries.

• The KIPS Transactions:PartD
• /
• v.13D no.4 s.107
• /
• pp.501-512
• /
• 2006

XML is the most popular platform-independent data expression which is used to communicate between loosely coupled heterogeneous systems such as B2B Applications or Workflow systems. The powerful query language XQuery has been developed to support diverse needs for querying XML documents. XQuery is designed to configure results from diverse data sources into a uniquely structured query result. Therefore, it became the standard for the XML query language. Although the latest XQuery supports heavy search functions including iterations, the grouping mechanism for data is too primitive and makes the query expression difficult and complex. Therefore, this work is focused on supporting the groupby clause in the query expression to process XQuery grouping. We suggest it to be a more efficient way to process grouping for restructuring and aggregation functions on XML data. We propose an XQuery EBNF that includes the groupby clause and implemented an XQuery processing system with grouping functions based on the eXist Native XML Database.

• Journal of Korea Multimedia Society
• /
• v.11 no.7
• /
• pp.905-913
• /
• 2008

Many heterogeneous XML documents are being widely used with the increasing employment of XML, and the importance of data structure research for more efficient document management has been growing steadily. We propose a query processing technique which uses parent node information in a partitioned inverted index tree. The searching efficiency of these heterogeneous documents is greatly influenced by the number of query processing and the amount of target data sets in many ways. Therefore, considering these two factors is very important for designing a data structure. First, our technique stores parent node's information in an inverted index table. Then using this information, we can reduce the number of query processing by half. Also, the amount of target data sets can be lessoned by using partitioned inverted index table. Some XML documents collected from the Internet will be used to demonstrate the new method, and its high efficiency will be compared with some of the existing searching methods.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.11 no.7
• /
• pp.1311-1317
• /
• 2007

Recently, due to the popularity and explosive growth of the Internet, the information exchange is increasing so rapidly over the Internet. Also the XML is becoming a standard as well as a major tool of data exchange on the Internet and thus we propose the new indexing technique for evaluating a path-oriented query and design and implementation of Path-oriented Query Processing System to give useful for users. In proposed indexing technique, which combined a binary trio structure with a path signature file to improve performance of XML document retrieval.