• Proceedings of the Korean Information Science Society Conference
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• 2002.10c
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• pp.22-24
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• 2002

XML이 웹상에서 데이타 교환의 표준으로 채택되면서 XML 데이타를 관계형 데이타베이스를 이용하여 저장하고 처리하는 것이 많이 연구되고 있다. 본 연구에서는 관계형 데이타베이스에 저장되어 있는 XML 데이타의 효과적인 질의 처리에 사용할 수 있는 인덱스 구조로서 디렉토리 인덱스를 제안한다. 디렉토리 인덱스는 정규 경로식 처리에 있어서 비트맵을 이용하여 조인 연산을 크게 줄여 처리 시간이 빠르며 인덱스의 갱신에도 효과적으로 대처할 수 있다.

• Proceedings of the Korea Multimedia Society Conference
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• 2002.11b
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• pp.343-346
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• 2002

관계데이터베이스를 이용한 XML 데이터저장방법에서 데이터가 삽입, 삭제, 갱신될 경우 인덱스를 제정의해야 하는 부담을 줄여주는 인덱스 기법을 제안한다. XML 데이터를 블록과 블록사이에 많아야 하나의 관계가 유지되도록 블록단위로 나누어 각 블록에 대해 Numbering 스킴을 적용하여 인덱스를 정의한다. 또한 정의된 인덱스를 이용하여 XML 질의 처리하기 Parent-Child Block Merge Algorithm과 Ancestor-Descendent Block Merge Algorithm을 제안한다.

• Journal of KIISE:Databases
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• v.31 no.1
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• pp.61-71
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• 2004

XML can describe a wide range of data, from regular to irregular and from flat to deeply nested. Thus, XML is rapidly emerging as the do facto standard for the Web document format since XML supports an efficient data exchange and integration. Also, to retrieve the data represented by XML, several XML query languages are proposed. XML query languages such as XPath and XQuery use path expressions to traverse irregularly structured data which comprise B% elements. To evaluate path expressions, various path indexes are proposed. However, traditional path indexes are constructed by utilizing only the XML data structure. Therefore, in this paper, we propose an adaptive path index which utilizes the XML data structure as well as query workloads. To improve the query performance, the adaptive path index proposed by this paper manages the frequently used paths and the structural summary of the XML data using a hash tree and a graph structure. Experimental results show that the adaptive path index improves the query performance typically 2 to 69 times compared with the existing indexes.

• The KIPS Transactions:PartD
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• v.11D no.2
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• pp.317-324
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• 2004

Containment queries for XML documents is one of the most important query types, and thus the efficient support for this type of query is crucial for XML databases. Recently, object-relational database management system (ORDBMS) vendors try to store and retrieve XML data in their products. In this paper, we propose an extensible index to support containment queries over the XML data stored as BLOB type in ORDBMSs. That is, we describe how to implement the index using the extensibility feature of an ORDBMS, and describe its usage.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11b
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• pp.4-6
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• 2005

스트리밍 XML 필터링 기법은 사용자가 등록한 질의를 만족하는 XML 문서를 찾아 사용자에게 XML 문서의 복사본을 돌러주는 것을 목적하고 있다. 본 연구는 Xfiiter와는 차별된 방법으로 역 인덱스를 사용하여 Xfilter처럼 역 인덱스가 XML 필터링 동안 동적으로 변하는 특성을 제거한다. 또한 늦은 질의 삭제 전략을 이용함으로써 질의 삭제 시간을 $50\%$ 이상 줄인다. 따라서 본 기법은 Xfilter에 비해 적은 필터링 시간과 질의 추가/삭제 시간을 보여준다. 또한 역 인덱스를 사용한 기법들의 제한점을 Yfilter와 비교하여 보여 준다.

• The KIPS Transactions:PartD
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• v.11D no.3
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• pp.509-518
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• 2004

Recently there has been some efforts to add XML full-text retrievals and XML updates into new standardization of XML queries. XML full-text retrievals plays an important role in XML query languages. of like tables in relational model an XML document has complex and unstructured natures. We believe that when we try to get some information from unstructured XML documents a full-text retrieval query is much more convenient approach than a regular structured query XML update is another core function that an XML query have to have. In this paper we propose an inverted index to support XML updates and XML full-text queries in relational environment. Performance comparisons exhibit that our approach maintains a comparable size of inverted indexes and it supports many full-text retrieval functions very well. It also shows very stable retrieval performance especially for large size of XML documents. Foremost our approach handles XML updates efficiently by removing cascading effects.

• Journal of KIISE:Databases
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• v.33 no.5
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• pp.513-525
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• 2006

Search results of XML keyword search are defined generally as the most specific elements containing all query keywords in the literature. The labels of XML elements and semantic information such as ontology, conceptual model, thesaurus, and so on, are used to improve the preciseness of the search results. This paper presents a hierarchical index for an efficient XML keyword query processing on the condition that returnable search concepts are defined and users' query concepts can be interpreted with the help of the semantic information. The hierarchical index separately stores the XML elements containing a keyword on the basis of the hierarchical relations of the concepts that the XML elements belong to, and makes it possible to obtain least common ancestors, which are candidates for the search results, with selectively reading the elements belonging to the concepts relevant to query concepts and without considering all the combinations of the elements having been read. This paper deals with how to organize the hierarchical index and how to process XML keyword queries with the index. In our experiment with the DBLP XML document and the XML documents in the INEX2003 test set, the hierarchical index worked well.

• Journal of Korea Multimedia Society
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• v.6 no.3
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• pp.397-408
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• 2003

Existing indexing mechanisms of XML data using numbering scheme have a drawback of rebuilding the entire index structure when insertion, deletion, and update occurs on the data. We propose a new indexing mechanism based on split blocks to cope with this problem. The XML data are split into blocks, where there exists at most a relationship between two blocks, and numbering scheme is applied to each block. This mechanism reduces the overhead of rebuilding index structures when insertion, deletion, and update occurs on the data. We also propose two algorithms, Parent-Child Block Merge Algorithm and Ancestor-Descendent Algorithm which retrieve the relationship between two entities in the XML hierarchy using this indexing mechanism. We also propose a mechanism in which the identifier of a block has the information of its Parents' block to expedite retrieval process of the ancestor-descendent relationship and also propose two algorithms. Parent-Child Block Merge Algorithm and Ancestor-Descendent Algorithm using this indexing mechanism.

• Journal of KIISE:Databases
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• v.37 no.3
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• pp.146-164
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• 2010

Due to an increasing volume of XML data, it is considered prudent to store XML data on an industry-strength database system instead of relying on a domain specific application or a file system. For shredded XML data stored in relational tables, however, it may not be straightforward to apply existing algorithms for twig query processing, since most of the algorithms require XML data to be accessed in a form of streams of elements grouped by their tags and sorted in a particular order. In order to support XML query processing within the common framework of relational database systems, we first propose several bitmap indexes and their strategies for supporting holistic twig joining on XML data stored in relational tables. Since bitmap indexes are well supported in most of the commercial and open-source database systems, the proposed bitmapped indexes and twig query processing strategies can be incorporated into relational query processing framework with more ease. The proposed query processing strategies are efficient in terms of both time and space, because the compressed bitmap indexes stay compressed during data access. In addition, we propose a hybrid index which computes twig query solutions with only bit-vectors, without accessing labeled XML elements stored in the relational tables.

• Journal of Korea Multimedia Society
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• v.9 no.10
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• pp.1257-1265
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• 2006

As XML is increasingly used, the need of researches which are related with XML in various fields is also augmented. Many XML document management systems have been actively developed especially for the storage, processing and retrieval of XML documents. The BitCube is a three dimensional bitmap index system that could be manipulated efficiently and improves the performance of document retrieval. However, the site of index is increase rapidly, when a new bit is added to the axis. This problem is caused by its three dimensional memory structure with document, path and word. We suggest a path combining strategy of XML documents in this paper to solve the problem of BitCube that mentioned above. To reduce the size of index, our approach combines sibling nodes that has same ancestor paths, and transforms word axis into value axis. The method reduces the size of index, when the system com poses the three dimensional bitmap index. It also improves the speed of retrieving, and takes efficiency in storage space.