Invention Grant
US08832074B2 System, method and computer-readable medium for dynamic skew avoidance for generic queries 有权
用于通用查询的动态偏差避免的系统,方法和计算机可读介质

  • Patent Title: System, method and computer-readable medium for dynamic skew avoidance for generic queries
  • Patent Title (中): 用于通用查询的动态偏差避免的系统,方法和计算机可读介质
  • Application No.: US12582734
    Application Date: 2009-10-21
  • Publication No.: US08832074B2
    Publication Date: 2014-09-09
  • Inventor: Xin ZhouOlli Pekka Kostamaa
  • Applicant: Xin ZhouOlli Pekka Kostamaa
  • Applicant Address: US OH Dayton
  • Assignee: Teradata US, Inc.
  • Current Assignee: Teradata US, Inc.
  • Current Assignee Address: US OH Dayton
  • Agent Steve McDonald; Ramin Mahboubiar
  • Main IPC: G06F17/30
  • IPC: G06F17/30
System, method and computer-readable medium for dynamic skew avoidance for generic queries
Abstract:
A system, method, and computer-readable medium that facilitate dynamic skew avoidance are provided. The disclosed mechanisms advantageously do not require any statistic information regarding which values are skewed in a column on which a query is applied. Query selectivity is evaluated at a check point and thereby facilitates accurate detection of an overloaded processing module. The successful detection of an overloaded processing module causes other processing modules to stop sending more skewed rows to the overloaded processing module. Detection of an overloaded processing module is made when the overloaded processing module has received more rows than a target number of rows. Further, skewed rows that are maintained locally rather than redistributed to a detected processing module may result in more processing modules becoming overloaded. Advantageously, the disclosed mechanisms provide for a final redistribution adjustment to provide for even distribution of rows among all processing modules.
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