What does "sorting projections on spatial columns" mean in Vertica Places ?
In Vertica Place documentation it says "Consider sorting projections on spatial
columns to improve the performance of .... ".
What does this mean in technical terms ? Assigning space filling curve values for objects so that the algorithm can filter them during the query processing ?
columns to improve the performance of .... ".
What does this mean in technical terms ? Assigning space filling curve values for objects so that the algorithm can filter them during the query processing ?
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The idea of sorting by a geometry column is to group geometries nearby in the space, which are likely going to be accessed together (e.g., range query), so that a (large, irrelevant) number of geometries can be pruned during query processing. Vertica uses an encoding of the geometries to determine order, but doesn't modify data while sorting.
Hope this helps.
Ariel