Search operations in nonspatial databases can be optimized using
SPATIAL
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:
Point queries that search for all objects that contain a given point
Region queries that search for all objects that overlap a given region
MySQL uses R-Trees with quadratic
splitting for SPATIAL
indexes on
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.
In a non-SPATIAL
index, you must declare a
prefix for any spatial column except for POINT
columns.
MyISAM
supports both SPATIAL
and non-SPATIAL
indexes. Other storage engines
support non-SPATIAL
indexes, as described in
Section 12.1.13, “CREATE INDEX
Syntax”.
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