PostGIS Snippets: Unterschied zwischen den Versionen
Aus Geoinformation HSR
Stefan (Diskussion | Beiträge) |
Stefan (Diskussion | Beiträge) |
||
Zeile 27: | Zeile 27: | ||
* Create ST_AsEWKT for geography and harmonize ST_AsText (depreciate with EWKT). | * Create ST_AsEWKT for geography and harmonize ST_AsText (depreciate with EWKT). | ||
* Create ST_GeogFromEWKT for geography and harmonize ST_GeogFromText (depreciate with EWKT). | * Create ST_GeogFromEWKT for geography and harmonize ST_GeogFromText (depreciate with EWKT). | ||
+ | |||
+ | |||
+ | == Bounding Box (bbox, box, mbr, ...) Constructors == | ||
+ | |||
+ | -- Works: | ||
+ | SELECT ST_AsText(ST_SetSRID('BOX3D(572126 5671279,1258837 6154972)'::box3d, 900913)) | ||
+ | SELECT ST_AsText(ST_SetSRID('BOX(572126 5671279,1258837 6154972)'::box2d, 900913)) | ||
+ | SELECT ST_AsText(ST_SetSRID(ST_MakeBox2D(ST_Point(572126, 5671279), ST_Point(1258837, 6154972)), 900913)) | ||
+ | SELECT ST_AsText(ST_SetSRID(ST_MakeBox3D(ST_Point(572126, 5671279), ST_Point(1258837, 6154972)), 900913)) | ||
+ | |||
+ | -- ...does not work: | ||
+ | SELECT ST_AsText(SetSRID('BOX2D(572126 5671279,1258837 6154972)'::box2d, 900913)) | ||
+ | SELECT ST_AsText(ST_GeomFromText('BOX2D(572126 5671279,1258837 6154972)', 900913)) | ||
+ | SELECT ST_AsText(ST_GeomFromText('BOX3D(572126 5671279,1258837 6154972)', 900913)) | ||
+ | |||
== hstore == | == hstore == | ||
Zeile 62: | Zeile 77: | ||
SELECT lower(tags->'cuisine') AS cuisine FROM planet_osm_polygon WHERE tags ? 'cuisine' | SELECT lower(tags->'cuisine') AS cuisine FROM planet_osm_polygon WHERE tags ? 'cuisine' | ||
) AS t GROUP BY cuisine ORDER BY c DESC; | ) AS t GROUP BY cuisine ORDER BY c DESC; | ||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− |
Version vom 16. Februar 2011, 15:36 Uhr
See also:
Inhaltsverzeichnis
Point Constructors
Point constructors for geometry and geography types: Howto construct and print a coordinate in EPSG:4326 and in lon/lat format in either textual or 'symbolic' form?
Works...
/*1 */ SELECT ST_AsEWKT(ST_GeomFromText('POINT(-71.06 42.28)', 4326)) -- ok, preferred if text input /*2 */ SELECT ST_AsEWKT(ST_GeomFromText('SRID=4326;POINT(-71.06 42.28)')) -- ok (if srid 'inline') /*3 */ SELECT ST_AsEWKT(ST_GeomFromEWKT('SRID=4326;POINT(-71.06 42.28)')) -- ok, but why then ST_GeomFromText? /*4 */ SELECT ST_AsEWKT('SRID=4326;POINT(-71.06 42.28)'::geometry) -- ok, but prefer 1/ST_GeomFromText /*5 */ SELECT ST_AsEWKT(ST_SetSRID('POINT(-71.06 42.28)'::geometry, 4326)) -- ok, but prefer 1/ST_GeomFromText /*6 */ SELECT ST_AsEWKT(ST_MakePoint(-71.06, 42.28, 4326)) -- ok for 'symbolic' form. But why no EWKT returning?
...does not work:
/*1 */ SELECT ST_AsEWKT(ST_GeogFromText('POINT(-71.06 42.28)', 4326)) -- ERROR: unknown ST_GeogFromText(): why? /*2a*/ SELECT ST_AsEWKT(ST_GeogFromText('SRID=4326;POINT(-71.06 42.28)')) -- ERROR: no ST_AsEWKT: why not? /*2b*/ SELECT ST_AsText(ST_GeogFromText('SRID=4326;POINT(-71.06 42.28)')) -- ok (if srid 'inline'); no AsEWKT /*3 */ SELECT ST_AsText(ST_GeogFromEWKT('SRID=4326;POINT(-71.06 42.28)')) -- ERROR: no ST_GeogFromEWKT: why? /*4 */ SELECT ST_AsText('SRID=4326;POINT(-71.06 42.28)'::geography) -- ok (no AsEWKT), but prefer 1/ST_GeomFromText /*5 */ SELECT ST_AsText(ST_SetSRID('POINT(-71.06 42.28)'::geography, 4326)) -- ERROR: ok SetSRID w. geography unnecessary /*6 */ Equivalent to ST_MakePoint for geography types missing: => ST_MakePointG?
Wishlist for future(!) PostGIS developments:
- Create ST_AsEWKT for geography and harmonize ST_AsText (depreciate with EWKT).
- Create ST_GeogFromEWKT for geography and harmonize ST_GeogFromText (depreciate with EWKT).
Bounding Box (bbox, box, mbr, ...) Constructors
-- Works:
SELECT ST_AsText(ST_SetSRID('BOX3D(572126 5671279,1258837 6154972)'::box3d, 900913)) SELECT ST_AsText(ST_SetSRID('BOX(572126 5671279,1258837 6154972)'::box2d, 900913)) SELECT ST_AsText(ST_SetSRID(ST_MakeBox2D(ST_Point(572126, 5671279), ST_Point(1258837, 6154972)), 900913)) SELECT ST_AsText(ST_SetSRID(ST_MakeBox3D(ST_Point(572126, 5671279), ST_Point(1258837, 6154972)), 900913))
-- ...does not work:
SELECT ST_AsText(SetSRID('BOX2D(572126 5671279,1258837 6154972)'::box2d, 900913)) SELECT ST_AsText(ST_GeomFromText('BOX2D(572126 5671279,1258837 6154972)', 900913)) SELECT ST_AsText(ST_GeomFromText('BOX3D(572126 5671279,1258837 6154972)', 900913))
hstore
Key-Value data type of PostgreSQL.
Index
Create index for a field of type hstore:
DROP INDEX planet_osm_point_tags; CREATE INDEX planet_osm_point_tags ON planet_osm_point USING gin (tags)
Create a index with expression:
DROP INDEX planet_osm_point_tags2; CREATE INDEX planet_osm_point_tags2 ON planet_osm_point USING btree (tags) WHERE tags->'natural'='peak';
Statistics: Counting the different values in hstore
SELECT lower(tags->'cuisine') as tags, count(*) AS count FROM planet_osm_point WHERE tags ? 'cuisine' GROUP BY 1 ORDER BY 2 DESC; "regional";416 "italian";197 "pizza";123 SELECT count(*) AS c, cuisine FROM ( SELECT lower(tags->'cuisine') AS cuisine FROM planet_osm_point WHERE tags ? 'cuisine' UNION ALL SELECT lower(tags->'cuisine') AS cuisine FROM planet_osm_polygon WHERE tags ? 'cuisine' ) AS t GROUP BY cuisine ORDER BY c DESC;