Independent XML storage based on XSD （XML Schema Document） is adopted in NXD（Native XML Data base）, XMI. storage structure based on tree-structure disassemble and the algorithm used in dynamically updating XML doc...Independent XML storage based on XSD （XML Schema Document） is adopted in NXD（Native XML Data base）, XMI. storage structure based on tree-structure disassemble and the algorithm used in dynamically updating XML document are provided in this paper. The main idea is that in term of data model of XML document, XML document is parsed to Document Structure-Tree with Hierarchical Model and Leaf-Data with Relation Model for storage. Simultaneously Proxy node is imported in order to solve the problem that XML data store in cross-blocks. And with XSD model information, sparse index is constructed to save storage space. It is proved that this storage structure could improve efficiency of XML document operation.展开更多
The problem of document rewriting is a fundamental problem in active XML（AXML） data exchange and usually has a higher complexity. Prior work was focused on string automaton theory. This paper tries to solve it by us...The problem of document rewriting is a fundamental problem in active XML（AXML） data exchange and usually has a higher complexity. Prior work was focused on string automaton theory. This paper tries to solve it by using tree automaton. More precisely, the paper firstly defines a new tree automaton, active XML tree automaton （AXTA）, which can efficiently represent the set of AXML documents produced by an AXML document or AXML document schema. And then, an algorithm for constructing AXTA automaton is also proposed. Finally, a polynomial time（PTIME） determining algorithm for AXML document rewriting is presented based on AXTA automaton.展开更多
In the XML community, exact queries allow users to specify exactly what they want to check and/or retrieve in an XML document. When they are applied to a semi-structured document or to a document with an overly comple...In the XML community, exact queries allow users to specify exactly what they want to check and/or retrieve in an XML document. When they are applied to a semi-structured document or to a document with an overly complex model, the lack or the ignorance of the explicit document model (DTD—Document Type Definition, Schema, etc.) increases the risk of obtaining an empty result set when the query is too specific, or, too large result set when it is too vague (e.g. it contains wildcards such as “*”). The reason is that in both cases, users write queries according to the document model they have in mind;this can be very far from the one that can actually be extracted from the document. Opposed to exact queries, preference queries are more flexible and can be relaxed to expand the search space during their evaluations. Indeed, during their evaluation, certain constraints (the preferences they contain) can be relaxed if necessary to avoid precisely empty results;moreover, the returned answers can be filtered to retain only the best ones. This paper presents an algorithm for evaluating such queries inspired by the TreeMatch algorithm proposed by Yao et al. for exact queries. In the proposed algorithm, the best answers are obtained by using an adaptation of the Skyline operator (defined in relational databases) in the context of documents (trees) to incrementally filter into the partial solutions set, those which satisfy the maximum of preferential constraints. The only restriction imposed on documents is No-Self-Containment.展开更多
结构化连接的效率直接影响着XML查询的性能,目前对XML的结构化连接大多都是基于编码的方法.介绍了一种全新的有效支持XML结构化连接的树索引CATI(compact ancestor tree index).CATI的基本思想是,对于给定的一个祖先后代查询(A-D查询)或...结构化连接的效率直接影响着XML查询的性能,目前对XML的结构化连接大多都是基于编码的方法.介绍了一种全新的有效支持XML结构化连接的树索引CATI(compact ancestor tree index).CATI的基本思想是,对于给定的一个祖先后代查询(A-D查询)或Twig查询,遍历XML文档,找出所有的祖先A的实例,用以建立CATI的主干;对于每个A实例,找出它的直接后代D的实例链接在它的后面.因为经典的结构连接算法Stack-Tree算法效率较高且使用较广,因此应用基于CATI的结构连接算法和基于Stack-Tree的结构连接算法就A-D查询和Twig查询做了大量实验.实验结果表明,基于CATI的结构化连接在一般查询情况下性能明显优于基于Stack-Tree的结构化连接.展开更多
基金Supported by the National Natural Science Foun-dation of China (60073045)
文摘Independent XML storage based on XSD （XML Schema Document） is adopted in NXD（Native XML Data base）, XMI. storage structure based on tree-structure disassemble and the algorithm used in dynamically updating XML document are provided in this paper. The main idea is that in term of data model of XML document, XML document is parsed to Document Structure-Tree with Hierarchical Model and Leaf-Data with Relation Model for storage. Simultaneously Proxy node is imported in order to solve the problem that XML data store in cross-blocks. And with XSD model information, sparse index is constructed to save storage space. It is proved that this storage structure could improve efficiency of XML document operation.
基金Supported by the Natural Science Foundation ofHeilongjiang Province(F00-06)
文摘The problem of document rewriting is a fundamental problem in active XML（AXML） data exchange and usually has a higher complexity. Prior work was focused on string automaton theory. This paper tries to solve it by using tree automaton. More precisely, the paper firstly defines a new tree automaton, active XML tree automaton （AXTA）, which can efficiently represent the set of AXML documents produced by an AXML document or AXML document schema. And then, an algorithm for constructing AXTA automaton is also proposed. Finally, a polynomial time（PTIME） determining algorithm for AXML document rewriting is presented based on AXTA automaton.
文摘In the XML community, exact queries allow users to specify exactly what they want to check and/or retrieve in an XML document. When they are applied to a semi-structured document or to a document with an overly complex model, the lack or the ignorance of the explicit document model (DTD—Document Type Definition, Schema, etc.) increases the risk of obtaining an empty result set when the query is too specific, or, too large result set when it is too vague (e.g. it contains wildcards such as “*”). The reason is that in both cases, users write queries according to the document model they have in mind;this can be very far from the one that can actually be extracted from the document. Opposed to exact queries, preference queries are more flexible and can be relaxed to expand the search space during their evaluations. Indeed, during their evaluation, certain constraints (the preferences they contain) can be relaxed if necessary to avoid precisely empty results;moreover, the returned answers can be filtered to retain only the best ones. This paper presents an algorithm for evaluating such queries inspired by the TreeMatch algorithm proposed by Yao et al. for exact queries. In the proposed algorithm, the best answers are obtained by using an adaptation of the Skyline operator (defined in relational databases) in the context of documents (trees) to incrementally filter into the partial solutions set, those which satisfy the maximum of preferential constraints. The only restriction imposed on documents is No-Self-Containment.
文摘结构化连接的效率直接影响着XML查询的性能,目前对XML的结构化连接大多都是基于编码的方法.介绍了一种全新的有效支持XML结构化连接的树索引CATI(compact ancestor tree index).CATI的基本思想是,对于给定的一个祖先后代查询(A-D查询)或Twig查询,遍历XML文档,找出所有的祖先A的实例,用以建立CATI的主干;对于每个A实例,找出它的直接后代D的实例链接在它的后面.因为经典的结构连接算法Stack-Tree算法效率较高且使用较广,因此应用基于CATI的结构连接算法和基于Stack-Tree的结构连接算法就A-D查询和Twig查询做了大量实验.实验结果表明,基于CATI的结构化连接在一般查询情况下性能明显优于基于Stack-Tree的结构化连接.
