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in one of the earth functions so that latitude and longitude to cartesian coordinates conversion will be more accurrate. (Previously a text string was built to provide as input which limited the accuracy to the number of digits printed.) The new functions were included in a recent patch to contrib/cube that has not as yet been accepted as of yet. I also added check constraints to the domain 'earth' since they are now working in 7.4. Bruno Wolff III
94 lines
3.1 KiB
MySQL
94 lines
3.1 KiB
MySQL
-- Adjust this setting to control where the objects get created.
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SET search_path = public;
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SET autocommit TO 'on';
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-- The earth functions rely on contrib/cube having been installed and loaded.
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-- earth() returns the radius of the earth in meters. This is the only
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-- place you need to change things for the cube base distance functions
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-- in order to use different units (or a better value for the Earth's radius).
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CREATE OR REPLACE FUNCTION earth() RETURNS float8
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LANGUAGE 'sql' IMMUTABLE
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AS 'SELECT \'6378168\'::float8';
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-- Astromers may want to change the earth function so that distances will be
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-- returned in degrees. To do this comment out the above definition and
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-- uncomment the one below. Note that doing this will break the regression
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-- tests.
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--
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-- CREATE OR REPLACE FUNCTION earth() RETURNS float8
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-- LANGUAGE 'sql' IMMUTABLE
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-- AS 'SELECT 180/pi()';
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-- Define domain for locations on the surface of the earth using a cube
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-- datatype with constraints. cube provides 3D indexing.
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-- The cube is restricted to be a point, no more than 3 dimensions
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-- (for less than 3 dimensions 0 is assumed for the missing coordinates)
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-- and that the point must be very near the surface of the sphere
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-- centered about the origin with the radius of the earth.
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CREATE DOMAIN earth AS cube
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CONSTRAINT not_point check(cube_is_point(value))
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CONSTRAINT not_3d check(cube_dim(value) <= 3)
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CONSTRAINT on_surface check(abs(cube_distance(value, '(0)'::cube) /
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earth() - 1) < '10e-7'::float8);
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CREATE OR REPLACE FUNCTION sec_to_gc(float8)
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RETURNS float8
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LANGUAGE 'sql'
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IMMUTABLE STRICT
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AS 'SELECT CASE WHEN $1 < 0 THEN 0::float8 WHEN $1/(2*earth()) > 1 THEN pi()*earth() ELSE 2*earth()*asin($1/(2*earth())) END';
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CREATE OR REPLACE FUNCTION gc_to_sec(float8)
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RETURNS float8
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LANGUAGE 'sql'
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IMMUTABLE STRICT
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AS 'SELECT CASE WHEN $1 < 0 THEN 0::float8 WHEN $1/earth() > pi() THEN 2*earth() ELSE 2*earth()*sin($1/(2*earth())) END';
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CREATE OR REPLACE FUNCTION ll_to_earth(float8, float8)
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RETURNS earth
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LANGUAGE 'sql'
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IMMUTABLE STRICT
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AS 'SELECT cube(cube(cube(earth()*cos(radians($1))*cos(radians($2))),earth()*cos(radians($1))*sin(radians($2))),earth()*sin(radians($1)))';
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CREATE OR REPLACE FUNCTION latitude(earth)
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RETURNS float8
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LANGUAGE 'sql'
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IMMUTABLE STRICT
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AS 'SELECT CASE WHEN cube_ll_coord($1, 3)/earth() < -1 THEN -90::float8 WHEN cube_ll_coord($1, 3)/earth() > 1 THEN 90::float8 ELSE degrees(asin(cube_ll_coord($1, 3)/earth())) END';
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CREATE OR REPLACE FUNCTION longitude(earth)
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RETURNS float8
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LANGUAGE 'sql'
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IMMUTABLE STRICT
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AS 'SELECT degrees(atan2(cube_ll_coord($1, 2), cube_ll_coord($1, 1)))';
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CREATE OR REPLACE FUNCTION earth_distance(earth, earth)
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RETURNS float8
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LANGUAGE 'sql'
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IMMUTABLE STRICT
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AS 'SELECT sec_to_gc(cube_distance($1, $2))';
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CREATE OR REPLACE FUNCTION earth_box(earth, float8)
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RETURNS cube
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LANGUAGE 'sql'
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IMMUTABLE STRICT
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AS 'SELECT cube_enlarge($1, gc_to_sec($2), 3)';
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--------------- geo_distance
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CREATE OR REPLACE FUNCTION geo_distance (point, point)
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RETURNS float8
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LANGUAGE 'C' IMMUTABLE STRICT AS 'MODULE_PATHNAME';
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--------------- geo_distance as operator <@>
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CREATE OPERATOR <@> (
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LEFTARG = point,
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RIGHTARG = point,
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PROCEDURE = geo_distance,
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COMMUTATOR = <@>
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);
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