幾何模型
更新時(shí)間：
Ganos Geometry是對(duì)象關(guān)系型數(shù)據(jù)庫PostgreSQL的一個(gè)空間幾何擴(kuò)展，Ganos Geometry遵循OpenGIS規(guī)范，使PostgreSQL增加了存儲(chǔ)和管理2D（X，Y）、3D（X，Y，Z）、4D（X，Y，Z，M）空間幾何數(shù)據(jù)的能力，并提供了空間幾何對(duì)象、索引、函數(shù)和操作符等豐富功能。
概述
幾何模型完全兼容PostGIS接口，支持已有應(yīng)用的平滑遷移。
快速入門
創(chuàng)建擴(kuò)展
--創(chuàng)建幾何擴(kuò)展 Create extension ganos_geometry with schema public cascade;重要請(qǐng)勿在一個(gè)Schema下同時(shí)創(chuàng)建Ganos和PostGIS擴(kuò)展，否則將報(bào)錯(cuò)
ERROR: table "spatial_ref_sys" is not a member of the extension being created。因?yàn)閯?chuàng)建Ganos和PostGIS擴(kuò)展時(shí)均會(huì)自動(dòng)創(chuàng)建表
spatial_ref_sys，造成表沖突。建議將Ganos和PostGIS擴(kuò)展創(chuàng)建在不同Schema下，或刪除PostGIS擴(kuò)展后，再安裝Ganos擴(kuò)展。創(chuàng)建幾何表
--方式一：直接創(chuàng)建帶geometry字段的表 CREATE TABLE ROADS ( ID int4, ROAD_NAME varchar(25), geom geometry(LINESTRING,3857) ); --方式二：先創(chuàng)建普通表，再附加幾何字段 CREATE TABLE ROADS ( ID int4, ROAD_NAME varchar(25) ); SELECT AddGeometryColumn( 'roads', 'geom', 3857, 'LINESTRING', 2);添加幾何約束
ALTER TABLE ROADS ADD CONSTRAINT geometry_valid_check CHECK (ST_IsValid(geom));導(dǎo)入幾何數(shù)據(jù)
INSERT INTO roads (id, geom, road_name) VALUES (1,ST_GeomFromText('LINESTRING(191232 243118,191108 243242)',3857),'北五環(huán)'); INSERT INTO roads (id, geom, road_name) VALUES (2,ST_GeomFromText('LINESTRING(189141 244158,189265 244817)',3857),'東五環(huán)'); INSERT INTO roads (id, geom, road_name) VALUES (3,ST_GeomFromText('LINESTRING(192783 228138,192612 229814)',3857),'南五環(huán)'); INSERT INTO roads (id, geom, road_name) VALUES (4,ST_GeomFromText('LINESTRING(189412 252431,189631 259122)',3857),'西五環(huán)'); INSERT INTO roads (id, geom, road_name) VALUES (5,ST_GeomFromText('LINESTRING(190131 224148,190871 228134)',3857),'東長安街'); INSERT INTO roads (id, geom, road_name) VALUES (6,ST_GeomFromText('LINESTRING(198231 263418,198213 268322)',3857),'西長安街');查詢幾何對(duì)象信息
SELECT id, ST_AsText(geom) AS geom, road_name FROM roads; -------------------------------- id | geom | road_name --------+-----------------------------------------+----------- 1 | LINESTRING(191232 243118,191108 243242) | 北五環(huán) 2 | LINESTRING(189141 244158,189265 244817) | 東五環(huán) 3 | LINESTRING(192783 228138,192612 229814) | 南五環(huán) 4 | LINESTRING(189412 252431,189631 259122) | 西五環(huán) 5 | LINESTRING(190131 224148,190871 228134) | 東長安街 6 | LINESTRING(198231 263418,198213 268322) | 西長安街 (6 rows)創(chuàng)建索引
--GiST索引 CREATE INDEX [indexname] ON [tablename] USING GIST ( [geometryfield] ); CREATE INDEX [indexname] ON [tablename] USING GIST ([geometryfield] gist_geometry_ops_nd); VACUUM ANALYZE [table_name] [(column_name)]; --舉例 Create INDEX sp_geom_index ON ROADS USING GIST(geom); VACUUM ANALYZE ROADS (geom); --創(chuàng)建BRIN索引 CREATE INDEX [indexname] ON [tablename] USING BRIN ( [geometryfield] ); CREATE INDEX [indexname] ON [tablename] USING BRIN ([geometryfield] brin_geometry_inclusion_ops_3d); CREATE INDEX [indexname] ON [tablename] USING BRIN ([geometryfield] brin_geometry_inclusion_ops_4d); --創(chuàng)建指定大小的brin索引 CREATE INDEX [indexname] ON [tablename] USING BRIN ( [geometryfield] ) WITH (pages_per_range = [number]);幾何對(duì)象存取
---判斷空間幾何對(duì)象是否是簡(jiǎn)單要素類型 SELECT ST_IsSimple(ST_GeomFromText('POLYGON((1 2, 3 4, 5 6, 1 2))')); st_issimple ------------- t (1 row) SELECT ST_IsSimple(ST_GeomFromText('LINESTRING(1 1,2 2,2 3.5,1 3,1 2,2 1)')); st_issimple ------------- f (1 row) --查詢地形中擁有環(huán)島且面積最大的城市 SELECT gid, name, ST_Area(the_geom) AS area FROM bc_municipality WHERE ST_NRings(the_geom) > 1 ORDER BY area DESC LIMIT 1; gid | name | area -----+--------------+------------------ 12 | 安寧市 | 257374619.430216 (1 row)空間測(cè)量、空間分析和空間關(guān)系判斷
--創(chuàng)建表bc_roads Create table bc_roads (gid serial, name varchar, the_geom geometry); --創(chuàng)建表bc_municipality Create table bc_municipality(gid serial, code integer, name varchar, the_geom geometry); --長度計(jì)算 SELECT sum(ST_Length(the_geom))/1000 AS km_roads FROM bc_roads; km_roads ------------------ 70842.1243039643 (1 row) --面積計(jì)算 SELECT ST_Area(the_geom)/10000 AS hectares FROM bc_municipality WHERE name = 'PRINCE GEORGE'; hectares ------------------ 32657.9103824927 (1 row) --使用ST_Contains函數(shù) SELECT m.name, sum(ST_Length(r.the_geom))/1000 as roads_km FROM bc_roads AS r, bc_municipality AS m WHERE ST_Contains(m.the_geom,r.the_geom) GROUP BY m.name ORDER BY roads_km; name | roads_km ----------------------------+------------------ SURREY | 1539.47553551242 VANCOUVER | 1450.33093486576 LANGLEY DISTRICT | 833.793392535662 BURNABY | 773.769091404338 PRINCE GEORGE | 694.37554369147 --使用ST_Covers函數(shù) SELECT ST_Covers(smallc,smallc) As smallinsmall, ST_Covers(smallc, bigc) As smallcoversbig, ST_Covers(bigc, ST_ExteriorRing(bigc)) As bigcoversexterior, ST_Contains(bigc, ST_ExteriorRing(bigc)) As bigcontainsexterior FROM (SELECT ST_Buffer(ST_GeomFromText('POINT(1 2)'), 10) As smallc, ST_Buffer(ST_GeomFromText('POINT(1 2)'), 20) As bigc) As foo; --Result smallinsmall | smallcoversbig | bigcoversexterior | bigcontainsexterior --------------+----------------+-------------------+--------------------- t | f | t | f (1 row) --使用ST_Disjoint函數(shù) SELECT ST_Disjoint('POINT(0 0)'::geometry, 'LINESTRING ( 2 0, 0 2 )'::geometry); st_disjoint --------------- t (1 row) SELECT ST_Disjoint('POINT(0 0)'::geometry, 'LINESTRING ( 0 0, 0 2 )'::geometry); st_disjoint --------------- f (1 row) --使用ST_Overlaps函數(shù) SELECT ST_Overlaps(a,b) As a_overlap_b, ST_Crosses(a,b) As a_crosses_b, ST_Intersects(a, b) As a_intersects_b, ST_Contains(b,a) As b_contains_a FROM (SELECT ST_GeomFromText('POINT(1 0.5)') As a, ST_GeomFromText('LINESTRING(1 0, 1 1, 3 5)') As b) As foo a_overlap_b | a_crosses_b | a_intersects_b | b_contains_a ------------+-------------+----------------+-------------- f | f | t | t --使用ST_Relate函數(shù) SELECT ST_Relate(ST_GeometryFromText('POINT(1 2)'), ST_Buffer(ST_GeometryFromText('POINT(1 2)'),2), '0FFFFF212'); st_relate ----------- t --使用ST_Touches函數(shù) SELECT ST_Touches('LINESTRING(0 0, 1 1, 0 2)'::geometry, 'POINT(1 1)'::geometry); st_touches ------------ f (1 row) SELECT ST_Touches('LINESTRING(0 0, 1 1, 0 2)'::geometry, 'POINT(0 2)'::geometry); st_touches ------------ t (1 row) --使用ST_Within函數(shù) SELECT ST_Within(smallc,smallc) As smallinsmall, ST_Within(smallc, bigc) As smallinbig, ST_Within(bigc,smallc) As biginsmall, ST_Within(ST_Union(smallc, bigc), bigc) as unioninbig, ST_Within(bigc, ST_Union(smallc, bigc)) as biginunion, ST_Equals(bigc, ST_Union(smallc, bigc)) as bigisunion FROM ( SELECT ST_Buffer(ST_GeomFromText('POINT(50 50)'), 20) As smallc, ST_Buffer(ST_GeomFromText('POINT(50 50)'), 40) As bigc) As foo; --Result smallinsmall | smallinbig | biginsmall | unioninbig | biginunion | bigisunion --------------+------------+------------+------------+------------+------------ t | t | f | t | t | t (1 row)刪除擴(kuò)展
Drop extension ganos_geometry cascade;
SQL參考
詳細(xì)SQL手冊(cè)請(qǐng)參見PostGIS官方手冊(cè)。
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