发明申请
- 专利标题: Consistent histogram maintenance using query feedback
- 专利标题(中): 使用查询反馈进行一致的直方图维护
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申请号: US11239044申请日: 2005-09-30
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公开(公告)号: US20070078808A1公开(公告)日: 2007-04-05
- 发明人: Peter Haas , Volker Markl , Nimrod Megiddo , Utkarsh Srivastava
- 申请人: Peter Haas , Volker Markl , Nimrod Megiddo , Utkarsh Srivastava
- 主分类号: G06F17/30
- IPC分类号: G06F17/30
摘要:
A novel method is employed for collecting optimizer statistics for optimizing database queries by gathering feedback from the query execution engine about the observed cardinality of predicates and constructing and maintaining multidimensional histograms. This makes use of the correlation between data columns without employing an inefficient data scan. The maximum entropy principle is used to approximate the true data distribution by a histogram distribution that is as “simple” as possible while being consistent with the observed predicate cardinalities. Changes in the underlying data are readily adapted to, automatically detecting and eliminating inconsistent feedback information in an efficient manner. The size of the histogram is controlled by retaining only the most “important” feedback.
公开/授权文献
- US07512574B2 Consistent histogram maintenance using query feedback 公开/授权日:2009-03-31
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