Merging synopses to determine number of distinct values in large databases
    51.
    发明申请
    Merging synopses to determine number of distinct values in large databases 有权
    合并摘要以确定大型数据库中不同值的数量

    公开(公告)号:US20080120275A1

    公开(公告)日:2008-05-22

    申请号:US11796110

    申请日:2007-04-25

    IPC分类号: G06F17/30

    摘要: A method and apparatus for merging synopses to determine a database statistic, e.g., a number of distinct values (NDV), is disclosed. The merging can be used to determine an initial database statistic or to perform incremental statistics maintenance. For example, each synopsis can pertain to a different partition, such that merging the synopses generates a global statistic. When performing incremental maintenance, only those synopses whose partitions have changed need to be updated. Each synopsis contains domain values that summarize the statistic. However, the synopses may initially contain domain values that are not compatible with each other. Prior to merging the synopses the domain values in each synopsis is made compatible with the domain values in the other synopses. The adjustment is made such that each synopsis represents the same range of domain values, in one embodiment. After “compatible synopses” are formed, the synopses are merged by taking the union of the compatible synopses.

    摘要翻译: 公开了用于合并概要以确定数据库统计量的方法和装置,例如多个不同值(NDV)。 合并可用于确定初始数据库统计信息或执行增量统计维护。 例如,每个概要可以涉及不同的分区,以便合并概要会生成全局统计量。 执行增量维护时,只需要更新其分区已更改的概要文件。 每个概要包含总结统计量的域值。 但是,这些概要可能最初包含彼此不兼容的域值。 在合并概要之前,每个概要中的域值与其他概要中的域值兼容。 在一个实施例中进行调整,使得每个概要表示相同范围的域值。 在形成“兼容简介”之后,通过兼容兼容简报的合并来合并概要。

    Techniques for pruning a data object during operations that join multiple data objects
    52.
    发明授权
    Techniques for pruning a data object during operations that join multiple data objects 有权
    在连接多个数据对象的操作期间修剪数据对象的技术

    公开(公告)号:US07020661B1

    公开(公告)日:2006-03-28

    申请号:US10193620

    申请日:2002-07-10

    IPC分类号: G06F17/30

    摘要: Techniques for eliminating one or more portions of a data object from any join step of an operation that joins multiple data objects include determining that an operation joins a first data object and a second data object. The second data object includes multiple portions. Each of multiple data units of the first data object is scanned. Based on data in the data units of the first data object, information is generated. The information indicates a portion of the second data object for exclusion. The indicated portion is excluded from an output of the operation. Only one or more portions of the second data object that are not indicated for exclusion in the information are included in a particular join step involving the second data object. By pruning a large second table, such as a fact table, the computational resources consumed by the joins are substantially reduced.

    摘要翻译: 用于从连接多个数据对象的操作的任何连接步骤中消除数据对象的一个​​或多个部分的技术包括确定操作连接第一数据对象和第二数据对象。 第二数据对象包括多个部分。 扫描第一数据对象的多个数据单元中的每一个。 基于第一数据对象的数据单元中的数据,生成信息。 该信息指示用于排除的第二数据对象的一部分。 指示的部分从操作的输出中排除。 仅在信息中未被指示排除的第二数据对象的一个​​或多个部分被包括在涉及第二数据对象的特定连接步骤中。 通过修剪诸如事实表的大的第二表,大大减少了连接消耗的计算资源。

    Method and mechanism for partition pruning
    53.
    发明授权
    Method and mechanism for partition pruning 有权
    分割修剪的方法和机制

    公开(公告)号:US06965891B1

    公开(公告)日:2005-11-15

    申请号:US09795904

    申请日:2001-02-27

    IPC分类号: G06F17/30

    摘要: A method and system for performing partition pruning for queries that include a non-single table predicate is disclosed. According to an embodiment of the invention, this type of query is processed by performing a transformation of the query to include additional predicates comprising subqueries. The transformed query includes single table predicates on the partitioning column of the table being queried, based upon join predicates that exist in the original query.

    摘要翻译: 公开了一种用于执行包括非单表谓词的查询的分割修剪的方法和系统。 根据本发明的实施例,通过执行查询的变换以包括包括子查询的附加谓词来处理这种类型的查询。 基于原始查询中存在的连接谓词,转换查询包括正在查询的表的分区列上的单表谓词。

    Automatic prevention of run-away query execution
    54.
    发明申请
    Automatic prevention of run-away query execution 审中-公开
    自动防止运行查询执行

    公开(公告)号:US20050177557A1

    公开(公告)日:2005-08-11

    申请号:US10936779

    申请日:2004-09-07

    IPC分类号: G06F7/00 G06F17/00 G06F17/30

    摘要: A run-away query execution is automatically identified by a background process that periodically looks at each of the currently executing queries and compares the current execution time with the execution time estimated by the optimizer. Each query execution having a negative execution time difference can be automatically identified as a run-away query execution. The query execution plans that result in run-away executions can then be automatically tuned to produce more efficient execution plans.

    摘要翻译: 一个后台进程会自动识别一个执行错误的查询,该后台进程定期查看当前正在执行的每个查询,并将当前执行时间与优化器估计的执行时间进行比较。 具有负执行时间差的每个查询执行可以被自动识别为一个逃跑查询执行。 导致执行失效的查询执行计划可以自动调整,以生成更有效的执行计划。