In this paper we propose a new DataGuide-based locking protocol for isolation of concurrent XML transactions. The protocol adopts DataGuide structure for locking purposes. We extend the multigranularity locking protoc...
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In this paper we propose a new DataGuide-based locking protocol for isolation of concurrent XML transactions. The protocol adopts DataGuide structure for locking purposes. We extend the multigranularity locking protocol by adding node and logical locks on DataGuide. This allows to enhance concurrency of XML-specific transactions, thereby increasing the overall system performance.
Nowadays, XML has emerged as the standard technique for storing and exchanging semistructured data. The retrieval and update of XML documents in the multi-user databases requires isolation of con- current transactions...
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ISBN:
(纸本)8854801224
Nowadays, XML has emerged as the standard technique for storing and exchanging semistructured data. The retrieval and update of XML documents in the multi-user databases requires isolation of con- current transactions from each other. This paper presents a novel scheduler to synchronize concurrent access to XML documents through XPath and update operations. Our method extends the conventional multigranularity locking scheme and adjusts it to the hierarchical nature of XML. We propose two kinds of locks on DataGuide structure: node and tree locks. Besides, we introduce logical locks on the DataGuide's subtrees to prevent phantoms appearance. A proposed scheduler takes into consideration the semantics of XPath and update operations which significantly increases the degree of concurrency. The proposed method is primarily being implemented in the native XML DBMS Sedna, but it is applicable to any existing XML DBMS that supports the DataGuide structure.
We address the problem of efficient support for active rules in XML database systems. We describe a general form of active rules for XML based on XQuery and a previously defined update language and present our method ...
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We address the problem of efficient support for active rules in XML database systems. We describe a general form of active rules for XML based on XQuery and a previously defined update language and present our method to support these rules. The method consists in active rules processing along with the execution of an update statement. The method efficiency is attained due to the identification of rules triggered by the update statement during the execution of this statement that allows avoiding the redundant processing of not triggered rules.
The modern XML query language called XQuery includes advanced facilities both to query and to transform XML data. An XQuery query optimizer should be able to optimize any query. For "querying" queries almost...
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The modern XML query language called XQuery includes advanced facilities both to query and to transform XML data. An XQuery query optimizer should be able to optimize any query. For "querying" queries almost all techniques inherited from SQL-oriented DBMS may be applied. The XQuery transformation facilities are XML-specific and have no counterparts in other query languages. That is why XQuery transformational queries need to be optimized with novel techniques. In this paper two kinds of such techniques (namely push predicates down XML element constructors and projection of transformation) are considered. A subset of XQuery for which these techniques can be fully implemented is identified. This subset seems to be the most interesting from the practical viewpoint. Rewriting rules for this subset are proposed and the correctness of these rules is formally justified. For the rest of the language we propose solutions that work for the most of common cases or consider the problems we have encountered.
The semantics of the core features of XML Schema in terms of XQuery 1.0 and XPath 2.0 data model algebraically defined is given. The database state is represented as a many sorted algebra whose sorts are sets of data ...
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The semantics of the core features of XML Schema in terms of XQuery 1.0 and XPath 2.0 data model algebraically defined is given. The database state is represented as a many sorted algebra whose sorts are sets of data ...
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The semantics of the core features of XML Schema in terms of XQuery 1.0 and XPath 2.0 data model algebraically defined is given. The database state is represented as a many sorted algebra whose sorts are sets of data type values and different kinds of nodes and whose operations are data type operations and node accessors. The values of some node accessors, such as "parent", "children" and "attributes", define a document tree with a definite order of nodes. The values of other node accessors help to make difference between kinds of nodes, learn the names, types and values associated with the corresponding document entities, etc., i.e., provide primitive facilities for a query language. As a result, a document can be easily mapped to its implementation in terms of nodes and accessors defined on them.
Research Summary: This research investigates the effects of poverty and state capital (i.e., state-sponsored support) on recidivism among women offenders. We seek also to determine whether criticisms directed at actua...
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Research Summary: This research investigates the effects of poverty and state capital (i.e., state-sponsored support) on recidivism among women offenders. We seek also to determine whether criticisms directed at actuarial risk tools, such as the failure to take into account gender-related factors (e.g., poverty status), have merit. A community corrections sample of 134 female felony offenders from one county in the State of Oregon and in the cities of Minneapolis and St. Paul, Minnesota is used to examine self-reports of rearrest and probation or parole violations over a six-month time period. Results from the logistic regression analyses show poverty status increases the odds of rearrest by a factor of 4.6, and it increases the odds of supervision violation by a factor of 12.7. In contrast, risk scores failed to predict recidivism once poverty status was taken into account. Among poor women offenders specifically, we find providing state-sponsored support to address short-term needs (e.g., housing) reduces the odds of recidivism by 83%. Not only do community corrections officers who make available state capital promote women's empowerment, they are also less likely to have clients who reoffend. Policy Implications: Our findings suggest that a commonly used actuarial risk assessment tool (i.e., the LSI-R) does not sufficiently take into account the economic marginality of women offenders. At a minimum, existing tools should be refined or supplemented with other sources of information. During the early stages of supervision, community corrections agencies should encourage their officers to refer and advocate for poor women to receive available sources of state capital (e.g., subsidized housing) to address critical short-term needs, which can improve their economic circumstances, help move them out of poverty, and reduce the likelihood of recidivism. More broadly, recent changes in welfare policy, such as “Working Toward Independence,” will experience (at best) limite
The article is devoted to the concept of the stepping commands in parallel debuggers. It reviews the main existing schemes (synchronous and asynchronous step implementations) and introduces a new kind of synchronous s...
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ISBN:
(纸本)0769521320
The article is devoted to the concept of the stepping commands in parallel debuggers. It reviews the main existing schemes (synchronous and asynchronous step implementations) and introduces a new kind of synchronous scheme that has several advantages over existing ones. In this scheme the debugger performs the dynamic analysis of the program state thus simplifying the program state presentation and control. The possible implementation of suggested scheme in MPI debuggers is discussed and the existing implementation in mpC Workshop parallel debugger is presented.
Summary form only given. The article is devoted to the concept of the stepping commands in parallel debuggers. It reviews the main existing schemes (synchronous and asynchronous step implementations) and introduces a ...
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Summary form only given. The article is devoted to the concept of the stepping commands in parallel debuggers. It reviews the main existing schemes (synchronous and asynchronous step implementations) and introduces a new kind of synchronous scheme that has several advantages over existing ones. In this scheme the debugger performs the dynamic analysis of the program state thus simplifying the program state presentation and control. The possible implementation of suggested scheme in MPI debuggers is discussed and the existing implementation in mpC Workshop parallel debugger is presented.
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