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4c1383efd1
points on the surface of the earth and locating points within a specified distance using an index based on the contrib/cube package. The new functions are all of language type sql. A couple of bugs in the old earthdistance function based on the point datatype are fixed. A regression test has been added for both sets of functions. The README file has been updated to include documentation on the new stuff. There are comments about how this package is also useful for Astronomers. Bruno Wolff III
91 lines
3.0 KiB
MySQL
91 lines
3.0 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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-- Check constraints aren't currently supported.
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CREATE DOMAIN earth AS cube;
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-- CONSTRAINT not_point check(is_point(earth))
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-- CONSTRAINT not_3d check(cube_dim(earth) <= 3)
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-- CONSTRAINT on_surface check(abs(cube_distance(earth, '(0)'::cube) /
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-- earth() - 1) < '10e-12'::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(\'(\'||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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