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    • 9. 发明授权
    • Techniques for bushy tree execution plans for snowstorm schema
    • 用于暴雪模式的丛林执行计划的技术
    • US08438152B2
    • 2013-05-07
    • US11927324
    • 2007-10-29
    • Rafi Ahmed
    • Rafi Ahmed
    • G06F7/00G06F17/30
    • G06F17/30498
    • Methods for transforming a query to simulate a bushy tree execution plan for queries containing joins in series are provided. Left deep tree execution plans are supported by most relational database systems but are inefficient at processing queries directed to databases with snowstorm schema. A snowstorm schema contains several large fact tables and many smaller dimension tables, which make reference to one another. Bushy tree execution plans can be much more efficient for processing queries to snowstorm schema. The decision to choose between left-deep and bushy tree execution plans are based on the relative costs of the two execution plans. The methods provided transform queries which are otherwise executed with left deep tree execution plans into queries which are executed with simulated bushy tree execution plans.
    • 提供了用于转换查询以模拟包含串联连接的查询的丛树执行计划的方法。 左深树执行计划是大多数关系数据库系统支持的,但在处理针对具有暴风雪模式的数据库的查询时效率低下。 暴风雪模式包含几个大事实表和许多较小的维度表,这些表彼此引用。 布什树执行计划可以更有效地处理对暴风雪模式的查询。 选择左深和深树执行计划的决定是基于两个执行计划的相对成本。 所提供的方法转换了查询,否则这些查询将使用左深树执行计划执行到使用模拟丛林执行计划执行的查询中。