• Journal of KIISE:Databases
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• v.31 no.4
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• pp.432-443
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• 2004

As the XML data has been widely used in the Internet, it is necessary to store and retrieve the XML data by using DBMSs. However, relational DBMSs suffer from the model difference between graph structure of the XML data and table forms in relational databases. We propose an ORDBMS-based DTD-dependent XML data management system Xing. Xing stores XML data in a DTD-dependent form in an object database. Since the object database schema has a graph structure and supports multi-valued attributes, mapping from an XML data model and queries into an object data model and OQLs is a simple problem. For rapid storing of large quantities of the XML data, we use SAX parser with customized Xing-tree which requires a small memory space compared with the DOM-tree. Xing also returns the query result in an XML document form. We have implemented the Xing system on top of UniSQL object-relational DBMS for the validity checking and performance comparison. For XML genome data from GenBank, and experimental evaluation shows that Xing can provide significant performance improvement (maximum 10 times) compared with the relational approach.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.4
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• pp.389-398
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• 2002

As XML has been proposed a standard format for organizing and exchanging data in the internet, many applications on managing XML data have been developed. Especially, there are many studies for storing XML documents. It is important to evaluate the performance for efficient storage techniques. In this work, we suggest an efficient technique for storing XML documents using an object-relational database model. We verify the efficiency of a new storage technique through the performance evaluation on XML storage techniques. The contributions of this paper is that we suggest an efficient storage technique using an existing data management model and evaluate the performance for storage techniques for XML documents including an new storage technique.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10a
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• pp.22-24
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• 2001

HL7은 텍스트 기반의 의료정보교환 표준이다. HL7메시지는 한 환자가 내원하여 퇴원할 때까지 여러종류의 메시지가 계속적으로 다량 발생하게 되는데, 그 메시지들의 일부 특정 세그먼트들은 반복적으로 생성되어 사용된다는 특징이 있다 그러므로 HL7메시지를 데이타베이스에 저장할 때는 불가피하게 특정 세그먼트들에 많은 중복이 발생하게 된다. 또한 HL7메시지는 프로세스 흐름중심으로 발생되므로, 중복을 제거한 환자중심의 데이터베이스 설계가 필요하다. 본 논문에서는 XML데이타베이스를 사용하여 HL7메시지를 저장하는 방식을 제안한다. 이는 XML DTD가 병원정보를 다루는 여러 의료정보표준들 상호간의 정보교환 및 공유를 위한 스키마로서의 역할을 할 뿐만 아니라, 인터넷을 통해 여러 가지 서비스 제공할 수 있도록 효과적인 저장 및 검색을 지원하기 때문이다. 이질적인 병원정보시스템을 가지고 있는 병원들 간에 의료정보를 교환하고, 환자들의 의료정보를 통합관리 하기 위한 XML데이터베이스를 설계하고 구현하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10c
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• pp.40-42
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• 2002

XML 문서가 웹에서 많이 사용됨에 따라, 기존의 DBMS를 이용하여 XML 문서를 저장하고 관리하는 XML 저장 시스템에 대한 연구가 활발히 진행 중이다. 그러나 지금까지의 연구는 대부분 풍부한 모델링 기능을 제공하는 객체관계형 DBMS보다는 관계형 DBMS에 기반하여 이루어져 왔다. 본 논문에서는 오디세우스 객체관계형 DBMS를 위한 XML 저장 시스템인 ODYSSEUS/XMLStore를 설계하고 구현한다. 첫째, XML 문서 구조에서 객체관계형 데이타베이스 스키마로의 매핑에 대해 분석한다. 둘째, 분석된 매핑을 기술하는 방법을 표준 언어인 XML Schema를 활용하여 제안한다. 셋째, 사용자가 정의한 매핑 정보에 의거하여 XML 문서를 객체관계형 데이타베이스에 저장하는 세부 알고리즘을 제안한다.

• Journal of KIISE:Databases
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• v.33 no.2
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• pp.224-238
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• 2006

As XML became the standard of data exchange in the internet, the needs for effective query processing for XML data in streaming environment is increasing. Applying the existing database technique which processes data with the unit of tuple to the streaming XML data causes the out-of-memory problem due to limited memory volume. Likewise the cost for searching query path and accessing specific data may be remarkably increased because of special structure of XML. In a word it is unreasonable to apply the existing database system to the streaming environment that processes query for partial data, not the whole one. Thus, it should be able to search partial streaming data that rapidly satisfies join predicate through using low-capacity memory, based on a store technique suitable to streaming XML data. In this thesis, in order to study the store technique for low-capacity memory, the PCDATA and the CDATA-related parts, which can be used as predicate on join query, were fetched and saved. In addition, in an attempt to compare rapid join predicates, the range window of streaming XML data was set with the object of selectively joining windows that satisfies the query, based on Cardinality * and + among the structure information of DTD.

• Journal of KIISE:Databases
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• v.33 no.3
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• pp.342-352
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• 2006

Current studies on storing XML data are focused on either mapping XML data to existing RDBMS efficiently or developing a native XML storage. Some native XML storages store each XML node with parsed object form. Clustering, the physical arrangement of each object, can be an important factor to increase the performance with this storing method. In this paper, we propose re-clustering techniques that can store an XML document efficiently. Proposed clustering technique uses path similarities among data nodes, which can reduce page I/Os when returning query results. And proposed technique can process a path query only using small number of clusters as possible instead of using all clusters. This enables efficient processing of path query because we can reduce search space by skipping unnecessary data. Finally, we apply existing clustering techniques to store XML data and compare the performance with proposed technique. Our results show that the performance of XML storage can be improved by using a proper clustering technique.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.6
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• pp.569-579
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• 2000

XML will be used in lots of areas in the Web environment as a method of information exchange, We have to use dat'abases to manipulate lots of XML documents efficiently, When we use database to manipulate XML, not only type of database but also its interface is important We develop a system using relational database, object-oriented database and wrapper to store XML data, of which interfaces are XML-View, ODMG C++ binding, OQL and DOM, We discuss pros and cons of each method by the implementation of the system, and propose an efficient manipulation method of XNIL documents.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04a
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• pp.581-583
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• 2003

XML (extensible Markup Language)은 확장성과 유연성을 통해 인터넷 상에서 데이타를 표현하고 교환하는 중요한 표준으로 자리잡고 있으며, XML 기반의 문서의 양도 증가하고 있다. 이러한 XML의 광범위한 사용에 따라 XML 저장 및 검색 시스템의 필요성이 증대되고 있다. 본 논문에서는 방대한 XML 데이타를 효율적으로 처리하고 검색하기 위해 XML 문서를 관계형 데이타베이스에 저장하고. 질의 언어로 XQuery를 사용하는 시스템을 설계하고 구현한다. 또한 다양한 XQuery의 실행을 통하여 제안한 시스템의 성능을 평가한다.

• Journal of KIISE:Databases
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• v.32 no.5
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• pp.558-566
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• 2005

The XML is the new standard fir data representation and exchange on the Internet. In this paper, we describe a new approach for evaluating a path-oriented query against XML document. In our approach, we propose the Parallel Match Indexing Fabric to speed up evaluation of path-oriented query using path signature and design the parallel match algorithm to perform a match process between a path signature of input query and path signatures of elements stored in the database. To construct a structure of the parallel match indexing, we first make the binary tie for all path signatures on an XML document and then which trie is transformed to the Parallel Match Indexing Fabric. Also we use the Parallel Match Indexing Fabric and a parallel match algorithm for executing a search operation of a path-oriented query. In our proposed approach, Time complexity of the algorithm is proportional to the logarithm of the number of path signatures in the XML document.

• Journal of KIISE:Databases
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• v.30 no.3
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• pp.252-272
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• 2003

The view mechanism provides users with appropriate portions of database through data filtering and integration. In the Web era where information proliferates, the view concept is also useful for XML, a future standard for data exchange on the Web. This paper proposes a method of implementing XML views called XML view indexing, whereby XML view xv is represented as an XML view index(XVI) which is a structure containing the identifiers of xv's underlying XML elements as well as the information on xv. Since XVI for xv stores just the identifiers of the XML elements but not the elements themselves, when a user requests to retrieve xv, its XVI should be materialized against xv's underlying XML documents. Also an efficient algorithm to incrementally maintain consistency of XVI given a update of xv's underlying XML documents is required. This paper proposes and implements data structures and algorithms for XML view indexing. The performance experiments on XML view indexing reveal that it outperforms view recomputation for repeated accesses to the view, and requires as much as about 30 times less storage space compared to XML view materialization though the latter takes less time for repeated accesses to the view due to no need of materialization.