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几何模型

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Ganos Geometry是对象关系型数据库PostgreSQL的一个空间几何扩展，Ganos Geometry遵循OpenGIS规范，使PostgreSQL增加了存储和管理2D（X，Y）、3D（X，Y，Z）、4D（X，Y，Z，M）空间几何数据的能力，并提供了空间几何对象、索引、函数和操作符等丰富功能。

概述

几何模型完全兼容PostGIS接口，支持已有应用的平滑迁移。

快速入门

  • 创建扩展

    --创建几何扩展
Create extension ganos_geometry with schema public cascade;
    重要

    请勿在一个Schema下同时创建Ganos和PostGIS扩展，否则将报错ERROR: table "spatial_ref_sys" is not a member of the extension being created。

    因为创建Ganos和PostGIS扩展时均会自动创建表spatial_ref_sys，造成表冲突。建议将Ganos和PostGIS扩展创建在不同Schema下，或删除PostGIS扩展后，再安装Ganos扩展。

  • 创建几何表

    --方式一：直接创建带geometry字段的表
CREATE TABLE ROADS ( ID int4, ROAD_NAME varchar(25), geom geometry(LINESTRING,3857) );

--方式二：先创建普通表，再附加几何字段
CREATE TABLE ROADS ( ID int4, ROAD_NAME varchar(25) );
SELECT AddGeometryColumn( 'roads', 'geom', 3857, 'LINESTRING', 2);

  • 添加几何约束

    ALTER TABLE ROADS ADD CONSTRAINT geometry_valid_check CHECK (ST_IsValid(geom));

  • 导入几何数据

    INSERT INTO roads (id, geom, road_name)
  VALUES (1,ST_GeomFromText('LINESTRING(191232 243118,191108 243242)',3857),'北五环');
INSERT INTO roads (id, geom, road_name)
  VALUES (2,ST_GeomFromText('LINESTRING(189141 244158,189265 244817)',3857),'东五环');
INSERT INTO roads (id, geom, road_name)
  VALUES (3,ST_GeomFromText('LINESTRING(192783 228138,192612 229814)',3857),'南五环');
INSERT INTO roads (id, geom, road_name)
  VALUES (4,ST_GeomFromText('LINESTRING(189412 252431,189631 259122)',3857),'西五环');
INSERT INTO roads (id, geom, road_name)
  VALUES (5,ST_GeomFromText('LINESTRING(190131 224148,190871 228134)',3857),'东长安街');
INSERT INTO roads (id, geom, road_name)
  VALUES (6,ST_GeomFromText('LINESTRING(198231 263418,198213 268322)',3857),'西长安街');

  • 查询几何对象信息

    SELECT id, ST_AsText(geom) AS geom, road_name FROM roads;

--------------------------------
     id | geom                                    | road_name
--------+-----------------------------------------+-----------
      1 | LINESTRING(191232 243118,191108 243242) | 北五环
      2 | LINESTRING(189141 244158,189265 244817) | 东五环
      3 | LINESTRING(192783 228138,192612 229814) | 南五环
      4 | LINESTRING(189412 252431,189631 259122) | 西五环
      5 | LINESTRING(190131 224148,190871 228134) | 东长安街
      6 | LINESTRING(198231 263418,198213 268322) | 西长安街
(6 rows)

  • 创建索引

    --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)];

--举例
Create INDEX sp_geom_index ON ROADS USING GIST(geom);
VACUUM ANALYZE ROADS (geom);

--创建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);
--创建指定大小的brin索引
CREATE INDEX [indexname] ON [tablename] USING BRIN ( [geometryfield] ) WITH (pages_per_range = [number]);

  • 几何对象存取

    ---判断空间几何对象是否是简单要素类型
 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)


--查询地形中拥有环岛且面积最大的城市
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   | 安宁市        | 257374619.430216
(1 row)

  • 空间测量、空间分析和空间关系判断

    --创建表bc_roads 
Create table bc_roads (gid serial, name varchar, the_geom geometry);

--创建表bc_municipality
Create table bc_municipality(gid serial, code integer, name varchar, the_geom geometry);

--长度计算
SELECT sum(ST_Length(the_geom))/1000 AS km_roads FROM bc_roads;

km_roads
------------------
70842.1243039643
(1 row)

--面积计算
SELECT ST_Area(the_geom)/10000 AS hectares FROM bc_municipality WHERE name = 'PRINCE GEORGE';

hectares
------------------
32657.9103824927
(1 row)
--使用ST_Contains函数
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函数
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函数
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函数
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函数
SELECT ST_Relate(ST_GeometryFromText('POINT(1 2)'), ST_Buffer(ST_GeometryFromText('POINT(1 2)'),2), '0FFFFF212');
st_relate
-----------
t

--使用ST_Touches函数
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函数
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)

  • 删除扩展

    Drop extension ganos_geometry cascade;

SQL参考

详细SQL手册请参见PostGIS官方手册。

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