文件名称:
Data Cube: A Relational Aggregation Operator
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文件大小: 153kb
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上传时间: 2015-03-05
详细说明： Data Cube: A Relational Aggregation Operator Generalizing Group-By, Cross-Tab, and Sub-Totals Abstract: Data analysis applications typically aggregate data across many dimensions looking for unusual patterns. The SQL aggregate functions and the GROUP BY operator produce zero-dimensional or one-dimensional answers. Applications need the N-dimensional generalization of these operators. This paper defines that operator, called the data cube or simply cube. The cube operator generalizes the histogram, cross-tabulation, roll-up, dri ll-down, and sub-total constructs found in most report writers. The cube treats each of the N aggregation attributes as a dimension of N-space. The aggregate of a particular set of attribute values is a point in this space. The set of points forms an N-dimensional cube. Super-aggregates are computed by aggregating the N-cube to lower dimensional spaces. Aggregation points are represented by an "infinite value", ALL. For example, the point (ALL,ALL,ALL,...,ALL, sum(*)) would represent the global sum of all items. Each ALL value actually represents the set of values contributing to that aggregation. ...展开收缩
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