Filter (geography Data Type)
A method that offers a fast, index-only intersection method to determine if a geography instance intersects another geography instance, assuming an index is available.
Returns 1 if a geography instance potentially intersects another geography instance. This method may produce a false-positive return, and the exact result may be plan-dependent. Returns an accurate 0 value (true negative return) if there is no intersection of geography instances found.
In cases where an index is not available, or is not used, the method will return the same values as STIntersects() when called with the same parameters.
.Filter ( other_geography )
Is another geography instance to compare against the instance on which Filter() is invoked.
SQL Server return type: bit
CLR return type: SqlBoolean
This method is not deterministic and is not precise.
The following example uses
Filter() to determine if two
geography instances intersect each other.
CREATE TABLE sample (id int primary key, g geography); INSERT INTO sample VALUES (0, geography::Point(45, -120, 4326)), (1, geography::Point(45, -120.1, 4326)), (2, geography::Point(45, -120.2, 4326)), (3, geography::Point(45, -120.3, 4326)), (4, geography::Point(45, -120.4, 4326)); CREATE SPATIAL INDEX sample_idx on sample(g); SELECT id FROM sample WHERE g.Filter(geography::Parse( 'POLYGON((-120.1 44.9, -119.9 44.9, -119.9 45.1, -120.1 45.1, -120.1 44.9))')) = 1;