Grid index-based dynamic top-k query method

A query method and grid index technology, which is applied in the computer field, can solve problems such as low query efficiency and inability to adapt to dynamic changes in large amounts of data, and achieve high query efficiency

Inactive Publication Date: 2017-12-26
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The purpose of the present invention is to provide a dynamic top-k query method based on a grid index, which solves the problem that the existing query method is not suitable for a large amount of dynamic changes in data, and the problem of low query efficiency

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Embodiment Construction

[0018] Below in conjunction with specific embodiment the present invention is described in detail:

[0019] (1) Establish TTI index;

[0020] In the TTI index, there is a torso node for mesh C i，j , then its left child is grid C i-1，j , whose right child is C i,j-1 , the middle child is C i-1，j-1 . If there is a left branch node C i，j , then its child is C i-1，j . If there is a right branch node C i，j , then its child is C i，j-1 . The index building module first needs to divide the data space into a grid. The length of the grid in each attribute dimension is δ, and establish a TTI tree index according to the grid subscript, and initialize RN(cid)=0, plink→null, area =0, record the subscripts O.i and O.j of the root node, and give the data point p. In the two-dimensional space of 1*1, its attribute value is (p.x 1 ,p.x 2 ) the grid number C where it is located i，j Can pass p.i=[p.x 1 / δ], p.j=[p.x 2 / δ] calculated. figure 2 Shown is the TTI index, the root node...

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Abstract

The invention discloses a grid index-based dynamic top-k query method. The method comprises the steps of dividing a data region into a plurality of grid units same in size, wherein each grid unit comprises data falling in the region; establishing a TTI tree index; inserting a grid into the index; from a top trunk node of the TTI index, calculating a k dominating capability of the grid through existing summary information in the grid by left-right traversal, until a judgment unit is found; dividing an influence region and a free region by utilizing the judgment unit; calculating a top-k result set in the influence region; and if the data with changed attribute values falls in the free region, not updating the top-k result set. If the data change occurs in the free region, the top-k result set is re-calculated from the step 3 through data insertion and deletion steps. The method has the beneficial effects that quick increment of a data amount and dynamic change of the data can be adapted; and the query efficiency is high.

Description

technical field [0001] The invention belongs to the technical field of computers and relates to a dynamic top-k query method based on a grid index. Background technique [0002] With the rapid development of mobile computing, top-k query and its calculation methods have attracted the attention of many researchers, mainly because the top-k query result set plays a very important role in many applications, such as social networking site friend query, E-commerce product query, stock trading premium stock query, real estate purchase query, etc. The top-k query selects a preference function and returns the first k data objects with the smallest (or largest) function value as the result, which is of great significance for data analysts to find meaningful objects for decision support. The top-k query returns the k best records based on the user's preferences. User preferences are composed of selection conditions and sorting functions. Different users not only have different requir...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F17/30
CPCG06F16/9535
Inventor 秦小麟邓丹苹李博涵鲍芝峰郑伟王雅楠关东海
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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