AB column diagram-based method for estimating spatial query selection rate
A space selection and space query technology, applied in computing, special data processing applications, instruments, etc., can solve the problems of repeated counting, can not well meet the spatial query optimization, and fail to estimate the subsequent node selection rate, etc., and achieve high precision. Effect
Inactive Publication Date: 2010-09-08
INST OF GEOGRAPHICAL SCI & NATURAL RESOURCE RES CAS
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Problems solved by technology
Spatial histograms built in this way have a serious flaw: the double counting problem
However, there is currently no histogram algorithm for estimating the selection rate of subsequent nodes, which cannot meet the requirements of spatial query optimization.
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[0036] 1, taking the vector data shown in Figure 3 as an example, illustrate the specific implementation steps of space selection query selectivity estimation in the present invention:
[0037] (1.1) generate the AB histogram for the vector data shown in Figure 3;
[0038] Use the MBR of each data object to replace the corresponding data object, divide the entire data space into grid units of 12 rows × 12 columns, and judge the ring bucket to which it belongs according to the location of the MBR of each object. If there is no ring bucket containing the object, then Add a ring bucket to the AB histogram, record the range of the ring bucket, and set the value in the bucket to 1; if there is a corresponding ring bucket containing the object, increase the value in the bucket by 1. Repeat this process until all data objects are assigned to the corresponding ring buckets. The MBR of the data object and the ring bucket are shown in Figure 3(a); the established AB histogram is shown ...
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The invention relates to an AB column diagram-based method for estimating a spatial query selection rate and belongs to the technical field of spatial data query and processing. The method comprises the following steps of: establishing an AB column diagram for vector data needing querying; giving a query operation condition by a user, wherein the selection rate of spatial selection operation is the sum of the product of the quantity of objects in each annular barrel and the probability of the barrel of meeting the given selection condition, and the selection rate of spatial connection operation is the sum of the product of the quantity of objects in each annular barrel in one data set and the maximum value of the probability of meeting the given connection condition between a plurality ofobjects in the other data set; and generating the AB column diagram of query result data according to the original AB column diagram and the probability value of a corresponding spatial relationship.The query selection rate of a spatial relationship which comprises disjoint, intersect, within, contains, overlap and the like can be accurately estimated, the column diagram of the query result datacan be generated from the original data column diagram and the requirement on the estimation of a subsequent node selection rate in a query tree is met.
Description
technical field [0001] The invention relates to a spatial query selection rate estimation method based on an AB histogram, and belongs to the technical field of spatial data query and processing. Background technique [0002] In recent years, spatial databases have become more and more important in many applications, such as geographic information systems (GIS), computer-aided design (CAD), image processing, multimedia systems, etc. Because spatial query can handle multi-dimensional data in spatial database and satisfy a wide range of application types, the research on spatial query has attracted much attention in recent years. This is because of the huge amount of spatial data, complex data structure, and expensive operation. The query optimization cost model is not fully applicable to spatial data, so the optimization of spatial query is bound to become the difficulty and breakthrough point of spatial applications. [0003] Spatial selection and spatial join are two of th...
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IPC IPC(8): G06F17/30
Inventor 程昌秀陈荣国周成虎朱焰炉张明波谢炯
Owner INST OF GEOGRAPHICAL SCI & NATURAL RESOURCE RES CAS