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System and method for pick-and-drop sampling
System and method for pick-and-drop sampling
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机译:拖放采样的系统和方法
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摘要
A database system includes an input to a database server configured to deliver a data stream formed of a sequence of elements, D={p1, p2, . . . , pm} of size m of numbers from {1, . . . , n} to the database server. The system further includes a computer program that causes a processor to approximate frequency moments (Fk) in the data stream, such that a frequency of an element (i) is defined as fi=|{j:pj=i}| and a k-th frequency moment of D is defined as; ]]> single pass through the data stream. The processor is caused to carry out the steps of locating elements (i) with a frequency ΩFk in the data stream as heavy elements and approximating fi as ≧ a fraction of fi to limit memory resources used by the processor to estimate Fk to O(n1−2/k log(n)) bits.
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