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公开(公告)号：US20090299989A1
公开(公告)日：2009-12-03
申请号：US12127971
申请日：2008-05-28
申请人： Ning Zhang , Thomas Baby , Nipun Agarwal
发明人： Ning Zhang , Thomas Baby , Nipun Agarwal
IPC分类号： G06F17/30
CPC分类号： G06F17/30469
摘要： Techniques for estimating a cost of executing a query are provided. A query includes multiple predicates, each of which is associated with a selectivity value that indicates a percentage of input that satisfies the condition of the corresponding predicate. The selectivity values are used to determine an estimated cost of executing the query. In one technique, a group of multiple predicates of a query are treated as a single predicate. Thus, a single selectivity value, rather than multiple selectivity values, is determined for that group. In a related technique, instead of determining a selectivity value of a predicate in isolation with respect to other predicates of a query, the selectivity value of a set of one or more predicates in a query is generated based on other predicates in the query.
摘要翻译： 提供了用于估计执行查询的成本的技术。 查询包括多个谓词，每个谓词与选择性值相关联，该选择性值指示满足相应谓词条件的输入百分比。 选择性值用于确定执行查询的估计成本。 在一种技术中，一组查询的多个谓词被视为单个谓词。 因此，为该组确定单个选择性值，而不是多个选择性值。 在相关技术中，代替相对于查询的其他谓词来隔离地确定谓词的选择性值，而不是基于查询中的其他谓词生成查询中的一个或多个谓词的选择性值。
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公开(公告)号：US09244979B2
公开(公告)日：2016-01-26
申请号：US12127971
申请日：2008-05-28
申请人： Ning Zhang , Thomas Baby , Nipun Agarwal
发明人： Ning Zhang , Thomas Baby , Nipun Agarwal
IPC分类号： G06F17/30
CPC分类号： G06F17/30469
摘要： Techniques for estimating a cost of executing a query are provided. A query includes multiple predicates, each of which is associated with a selectivity value that indicates a percentage of input that satisfies the condition of the corresponding predicate. The selectivity values are used to determine an estimated cost of executing the query. In one technique, a group of multiple predicates of a query are treated as a single predicate. Thus, a single selectivity value, rather than multiple selectivity values, is determined for that group. In a related technique, instead of determining a selectivity value of a predicate in isolation with respect to other predicates of a query, the selectivity value of a set of one or more predicates in a query is generated based on other predicates in the query.
摘要翻译： 提供了用于估计执行查询的成本的技术。 查询包括多个谓词，每个谓词与选择性值相关联，该选择性值指示满足相应谓词条件的输入百分比。 选择性值用于确定执行查询的估计成本。 在一种技术中，一组查询的多个谓词被视为单个谓词。 因此，为该组确定单个选择性值，而不是多个选择性值。 在相关技术中，代替相对于查询的其他谓词来隔离地确定谓词的选择性值，而不是基于查询中的其他谓词生成查询中的一个或多个谓词的选择性值。
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公开(公告)号：US20090125480A1
公开(公告)日：2009-05-14
申请号：US11937357
申请日：2007-11-08
IPC分类号： G06F17/30
CPC分类号： G06F17/30932 , G06F17/30935
摘要： A query is rewritten to combine streaming evaluation and XML index evaluation. The query is rewritten to include a streaming operator (e.g. function) that, when executed, uses streaming evaluation. Further, the query is rewritten so that XML index evaluation of a path expression also produces location information that identifies the location of a node within an XML document. The streaming operator is able to exploit the location information to begin and end scanning rather than scanning the entire XML document.
摘要翻译： 重写查询以组合流评估和XML索引评估。 该查询被重写以包括流执行器（例如，功能），当被执行时，使用流评估。 此外，重写该查询，使得路径表达式的XML索引评估还产生标识XML文档中的节点的位置的位置信息。 流操作员能够利用位置信息开始和结束扫描，而不是扫描整个XML文档。
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公开(公告)号：US08180791B2
公开(公告)日：2012-05-15
申请号：US11937357
申请日：2007-11-08
IPC分类号： G06F7/00
CPC分类号： G06F17/30932 , G06F17/30935
摘要： A query is rewritten to combine streaming evaluation and XML index evaluation. The query is rewritten to include a streaming operator (e.g. function) that, when executed, uses streaming evaluation. Further, the query is rewritten so that XML index evaluation of a path expression also produces location information that identifies the location of a node within an XML document. The streaming operator is able to exploit the location information to begin and end scanning rather than scanning the entire XML document.
摘要翻译： 重写查询以组合流评估和XML索引评估。 该查询被重写以包括流执行器（例如，功能），当被执行时，使用流评估。 此外，重写该查询，使得路径表达式的XML索引评估还产生标识XML文档中的节点的位置的位置信息。 流操作员能够利用位置信息开始和结束扫描，而不是扫描整个XML文档。
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5.发明授权Global query normalization to improve XML index based rewrites for path subsetted index 有权全局查询规范化，以改进路径子集索引的基于XML索引的重写公开(公告)号：US07991768B2
公开(公告)日：2011-08-02
申请号：US11937268
申请日：2007-11-08
CPC分类号： G06F17/30911 , G06F17/30935
摘要： Techniques for processing a query that includes a path expression are provided. A query processor determines whether an XML index may be used to execute the query instead of having to scan multiple XML documents. The query is parsed and normalized, which results in multiple normalized path expressions that are based on the original path expression. If the XML index is a path-subsetted index, then the query processor generates annotated path expressions based on the normalized path expressions. The query processor determines whether each of the annotated path expressions is satisfiable by the path-subsetted XML index. If so, then the XML index is used to process the query.
摘要翻译： 提供了处理包含路径表达式的查询的技术。 查询处理器确定是否可以使用XML索引来执行查询，而不必扫描多个XML文档。 查询被解析和归一化，这导致基于原始路径表达式的多个标准化路径表达式。 如果XML索引是路径子集索引，则查询处理器将根据归一化的路径表达式生成带注释的路径表达式。 查询处理器确定每个注释路径表达式是否由路径子集的XML索引满足。 如果是这样，则使用XML索引来处理查询。
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6.发明授权Query optimization by specifying path-based predicate evaluation in a path-based query operator 有权通过在基于路径的查询运算符中指定基于路径的谓词评估来查询优化公开(公告)号：US08161035B2
公开(公告)日：2012-04-17
申请号：US12478147
申请日：2009-06-04
IPC分类号： G06F17/30
CPC分类号： G06F17/30938 , G06F17/30463
摘要： The approaches described herein provide an efficient way for a database server to process certain kinds of queries over XML data stored in an object-relational database that require the evaluation of a predicate expression with one or more path-based operands. A predicate expression part of a XQuery or SQL WHERE clause that returns a boolean value. A database server first determines whether the query qualifies for this particular kind of optimization, then rewrites the query using an enhanced query operator syntax for specifying the predicate expression to be evaluated. The enhanced query operator subsumes the work of a second path-based query operator, resulting in the suppression of the WHERE EXISTS subquery. The rewritten query operator is used to generate a query execution plan that provides for several query execution optimizations.
摘要翻译： 本文描述的方法为数据库服务器处理某些类型的查询提供了一种有效的方法，该XML数据存储在需要使用一个或多个基于路径的操作数的谓词表达式的对象关系数据库中。 XQuery或SQL WHERE子句的谓词表达式部分，返回一个布尔值。 数据库服务器首先确定查询是否符合此特定类型的优化，然后使用增强型查询运算符语法重写查询，以指定要评估的谓词表达式。 增强型查询操作符包含第二个基于路径的查询运算符的工作，从而抑制了WHERE EXISTS子查询。 重写的查询运算符用于生成提供多个查询执行优化的查询执行计划。
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公开(公告)号：US08250062B2
公开(公告)日：2012-08-21
申请号：US11938017
申请日：2007-11-09
CPC分类号： G06F17/30938 , G06F17/2247 , G06F17/2258
摘要： A database system may perform a streaming evaluation of an XPath expression by utilizing an XPath evaluation component in tandem with an XML event-streaming component. For a more optimal filtered streaming evaluation, the XML event-streaming component may provide an interface whereby the evaluation component sends certain criteria to the event-streaming component when requesting an XML event. The criteria may be based on a next unmatched step in the XPath expression. In response to the request for an XML event, the event-streaming component may only return events that match the criteria. The evaluation component may be, for example, a compiled state machine for the XPath expression. The criteria may be pre-compiled for each possible state in the state machine. The event-streaming component may also utilize the criteria along with schema information to skip parsing of certain segments of XML data.
摘要翻译： 数据库系统可以通过与XML事件流组件一起使用XPath评估组件来执行XPath表达式的流评估。 对于更优化的过滤流评估，XML事件流组件可以提供一个接口，当请求XML事件时，评估组件向事件流组件发送特定标准。 标准可能基于XPath表达式中的下一个不匹配的步骤。 响应对XML事件的请求，事件流组件可能只返回符合条件的事件。 评估组件可以是例如XPath表达式的编译状态机。 可以对状态机中的每个可能的状态预先准备标准。 事件流组件还可以利用标准以及模式信息来跳过某些XML数据段的解析。
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8.发明申请Query Optimization by Specifying Path-Based Predicate Evaluation in a Path-Based Query Operator 有权通过在基于路径的查询运算符中指定基于路径的谓词评估来进行查询优化公开(公告)号：US20100312756A1
公开(公告)日：2010-12-09
申请号：US12478147
申请日：2009-06-04
IPC分类号： G06F7/00
CPC分类号： G06F17/30938 , G06F17/30463
摘要： The approaches described herein provide an efficient way for a database server to process certain kinds of queries over XML data stored in an object-relational database that require the evaluation of a predicate expression with one or more path-based operands. A predicate expression part of a XQuery or SQL WHERE clause that returns a boolean value. A database server first determines whether the query qualifies for this particular kind of optimization, then rewrites the query using an enhanced query operator syntax for specifying the predicate expression to be evaluated. The enhanced query operator subsumes the work of a second path-based query operator, resulting in the suppression of the WHERE EXISTS subquery. The rewritten query operator is used to generate a query execution plan that provides for several query execution optimizations.
摘要翻译： 本文描述的方法为数据库服务器处理某些类型的查询提供了一种有效的方法，该XML数据存储在需要使用一个或多个基于路径的操作数的谓词表达式的对象关系数据库中。 XQuery或SQL WHERE子句的谓词表达式部分，返回一个布尔值。 数据库服务器首先确定查询是否符合此特定类型的优化，然后使用增强型查询运算符语法重写查询，以指定要评估的谓词表达式。 增强型查询操作符包含第二个基于路径的查询运算符的工作，从而抑制了WHERE EXISTS子查询。 重写的查询运算符用于生成提供多个查询执行优化的查询执行计划。
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公开(公告)号：US20100145957A1
公开(公告)日：2010-06-10
申请号：US12328642
申请日：2008-12-04
CPC分类号： G06F17/30935
摘要： Techniques are provided for estimating the cardinality of a virtual result table that is produced by executing path-based table functions within a query, such as the XMLTABLE function. Some path-based table functions apply a path expression to input from a base table of XML documents to select rows to produce the result table. Path statistics are collected for the path expressions for the base table. The path statistics are used to estimate the cardinalities of the result table. The estimated cardinality of the result table is useful for estimating costs of query execution plans that are generated for the query.
摘要翻译： 提供了用于估计通过在查询中执行基于路径的表函数（例如XMLTABLE函数）产生的虚拟结果表的基数的技术。 一些基于路径的表函数将路径表达式应用于从XML文档的基表中输入，以选择行以生成结果表。 针对基表的路径表达式收集路径统计信息。 路径统计信息用于估计结果表的基数。 结果表的估计基数对于为查询生成的查询执行计划的估计成本很有用。
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公开(公告)号：US20090327252A1
公开(公告)日：2009-12-31
申请号：US12145659
申请日：2008-06-25
申请人： Ning Zhang , Sam Idicula , Nipun Agarwal
发明人： Ning Zhang , Sam Idicula , Nipun Agarwal
IPC分类号： G06F17/30
CPC分类号： G06F17/30463 , G06F17/30929
摘要： Techniques for estimating the cost of processing a database statement that includes one or more path expressions are provided. One aspect of cost is I/O cost, or the cost of reading data from persistent storage into memory according to a particular streaming operator. Binary-encoded XML data is stored in association with a synopsis that summarizes the binary-encoded XML data. The synopsis includes skip length information for one or more elements and indicates, for each such element, how large (e.g., in bytes) the element is in storage. The skip length information of a particular element thus indicates how much data may be skipped during I/O if the particular element does not match the path expression that is input to the streaming operator. The skip length information of one or more elements is used to estimate the cost of processing the database statement.
摘要翻译： 提供了用于估计处理包含一个或多个路径表达式的数据库语句的成本的技术。 成本的一个方面是I / O成本，或者根据特定的流媒体运营商从永久存储器读取数据到存储器的成本。 二进制编码的XML数据与总结二进制编码的XML数据的概要相关联地存储。 概要包括一个或多个元素的跳过长度信息，并且针对每个这样的元素指示该元素在存储中的大小（例如，以字节为单位）。 因此，特定元素的跳过长度信息因此表示如果特定元素与输入到流媒体操作者的路径表达式不匹配，则可以在I / O期间跳过多少数据。 一个或多个元素的跳过长度信息用于估计处理数据库语句的成本。
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