18.6. Optimizing Spatial Analysis
Search operations in non-spatial databases can be optimized using
indexes. This is true for spatial databases as well. With the help
of a great variety of multi-dimensional indexing methods that have
previously been designed, it is possible to optimize spatial
searches. The most typical of these are:
MySQL uses R-Trees with quadratic
splitting to index spatial columns. A spatial index is
built using the MBR of a geometry. For most geometries, the MBR is
a minimum rectangle that surrounds the geometries. For a
horizontal or a vertical linestring, the MBR is a rectangle
degenerated into the linestring. For a point, the MBR is a
rectangle degenerated into the point.
It is also possible to create normal indexes on spatial columns.
You are required to declare a prefix for any (non-spatial) index
on a spatial column excepting