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    • 3. 发明申请
    • System and method for segmented evaluation of database queries
    • 数据库查询分段评估的系统和方法
    • US20050097100A1
    • 2005-05-05
    • US10998761
    • 2004-11-29
    • Cesar Galindo-LegariaGoetz GraefeMilind JoshiRoss Bunker
    • Cesar Galindo-LegariaGoetz GraefeMilind JoshiRoss Bunker
    • G06F7/00G06F17/30
    • G06F17/30501G06F17/3046G06F17/30466G06F17/30498Y10S707/99933Y10S707/99943
    • A method of satsfying a database query includes evaluating certain joins on a per-segment basis. An expression tree is produced for the query, and the expression tree is evaluated to identify joins whose operands are two instances of the same relation and whose join predicate conjunctively includes an equality comparison between two instances of the same column. When such a join is identified, it may be evaluated by segmenting the operand relation according to the columns that are compared for equality in the predicate. The join is then evaluated by performing the join operation separately on each segment. Segments may be spooled separately, thereby exploiting the efficiencies obtained by spooling even where the entire relation is too large to fit in the spool. Execution iterators are provided for spooling successive segments and for applying the join to the spooled segment.
    • 饱和数据库查询的方法包括基于每个段来评估某些联接。 为查询生成表达式树,并且对表达式树进行评估,以标识其操作数是相同关系的两个实例的连接,并且其连接谓词连接地包含同一列的两个实例之间的等效比较。 当识别出这样的连接时,可以通过根据在谓词中的相等性进行比较的列分割操作数关系来评估操作数关系。 然后通过在每个段上分别执行连接操作来评估连接。 分段可以单独地卷绕,从而利用即使在整个关系太大而不能装入卷轴的情况下通过卷绕获得的效率。 提供执行迭代器用于假脱机连续的段并将连接应用到假脱机段。