| 摘要 |
There is provided a method, a system and a machine readable medium to execute a spatial query against a plurality of input tables of a distributed database. The method comprises: mapping spatial objects of a first input table to a first spatial grid, the first spatial grid including a plurality of first spatial cells; redistributing the spatial objects of the first input table to a first intermediate table of one or more access module processors based on the first spatial cell of the first spatial grid to which each of the spatial objects is mapped; determining whether one or more first spatial cells of the first spatial grid are skewed; subdividing each of the skewed one or more first spatial cells to a second spatial grid, the second spatial grid including a plurality of second spatial cells; mapping spatial objects of the first intermediate file to the second spatial grid, the second spatial grid including a plurality of second spatial cells; redistributing the spatial objects of the first intermediate file to one or more access module processors based on the second spatial cell of the second spatial grid to which each of the spatial objects is mapped; mapping spatial objects of a second input table to the first spatial grid and the second spatial grid; redistributing the spatial objects of the second input table to a second intermediate file of one or more access module processors based on the first spatial cell of the first spatial grid and the second spatial cell of the second spatial grid to which each of the spatial objects is mapped; and joining the spatial objects of the first intermediate file to spatial objects of the second intermediate file for each first spatial cell of the first spatial grid or the second spatial cell of the second spatial grid.
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