Acquisition method by aid of k-dominant contour points and device

Abstract

An embodiment of the invention discloses an acquisition method by the aid of k-dominant contour points and a device. In the method, when a data set is update at a time, points to be processed do not need to be compared with traditional contour points, but is compared with the k-dominant contour points with the amount smaller than that of the traditional contour points. In addition, the concept of quasi-contour points is introduced, a part of the points to be processed are compared with the quasi-contour points, and the amount of computation is reduced due to the fact that the quasi-contour points are easier to maintain as compared with the traditional contour points. Simultaneously, a dominance relation chain table is introduced into the acquisition method, k-dominant relation among data points is kept, and is used after the data set is updated, so that repeated computation of the k-dominant relation among the data points is avoided, and the amount of computation is reduced.

Description

technical field [0001] The invention relates to the field of databases, in particular to a method and device for acquiring k-dominant contour points. Background technique [0002] In a data set D, if and only if the data point p j Values ​​of all dimensions above are better than or equal to p i values ​​of all dimensions above, and there exists a dimension t such that p j .s t better than p i .s t , then the data point p j Dominate data point p on space S i . The contour data points are those data points that are not dominated in the data set D, and the contour data point set can be obtained by means of contour query. In the process of database application, users often need to obtain useful information from contour data points, so the contour query method has been widely used. [0003] There are currently two types of contour data points obtained by contour query: one is the traditional contour point, if and only if there is no data point in the data set that domina...

AI Technical Summary

Problems solved by technology

[0007] Although the k-dominant contour points are not updated as frequently as the traditional contour points, in the environment of frequently updating data sets, the update of any data point may lead to the update of traditional contour points, so that we need to update the data set every time When , the traditional contour points are recalculated, and the k-dominant contour points are calculated according to the latest traditional contour points. However, the number of traditional contour points contained in the data set D is very large. In some extreme cases, the traditional contour points The total number of is even close to the size of the original data. Every time the data set D is updated, the traditional contour points are recalculated, and the k-dominant contour points are calculated according to the traditional contour points. This calculation amount is very large, and the calculation process is very time consuming

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