PolarDB:Geometry model

-- Create a geometry extension.
Create extension ganos_geometry cascade;

-- Create a geometry topology extension.
Create extension ganos_geometry_topology;

-- Create an SFCGAL plug-in extension.
Create extension ganos_geometry_sfcgal;

-- Method 1: Create a table with a geometry field.
CREATE TABLE ROADS (ID int4, ROAD_NAME varchar(25), geom geometry(LINESTRING,3857));

-- Method 2: Create a common table and then add a geometry field.
CREATE TABLE ROADS (ID int4, ROAD_NAME varchar(25));
SELECT AddGeometryColumn('roads', 'geom', 3857, 'LINESTRING', 2);

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

INSERT INTO roads (id, geom, road_name)
  VALUES (1,ST_GeomFromText('LINESTRING(191232 243118,191108 243242)',3857),'North Fifth-Ring Road');
INSERT INTO roads (id, geom, road_name)
  VALUES (2,ST_GeomFromText('LINESTRING(189141 244158,189265 244817)',3857),'East Fifth-Ring Road');
INSERT INTO roads (id, geom, road_name)
  VALUES (3,ST_GeomFromText('LINESTRING(192783 228138,192612 229814)',3857),'South Fifth-Ring Road');
INSERT INTO roads (id, geom, road_name)
  VALUES (4,ST_GeomFromText('LINESTRING(189412 252431,189631 259122)',3857),'West Fifth-Ring Road');
INSERT INTO roads (id, geom, road_name)
  VALUES (5,ST_GeomFromText('LINESTRING(190131 224148,190871 228134)',3857),'East Chang''an Avenue');
INSERT INTO roads (id, geom, road_name)
  VALUES (6,ST_GeomFromText('LINESTRING(198231 263418,198213 268322)',3857),'West Chang''an Avenue');

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

--------------------------------
     id | geom                                    | road_name
--------+-----------------------------------------+-----------
      1 | LINESTRING(191232 243118,191108 243242) | North Fifth-Ring Road
      2 | LINESTRING(189141 244158,189265 244817) | East Fifth-Ring Road
      3 | LINESTRING(192783 228138,192612 229814) | South Fifth-Ring Road
      4 | LINESTRING(189412 252431,189631 259122) | West Fifth-Ring Road
      5 | LINESTRING(190131 224148,190871 228134) | East Chang'an Avenue
      6 | LINESTRING(198231 263418,198213 268322) | West Chang'an Avenue
(6 rows)

-- Create a GiST index.
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)];

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

-- Create a block range index (BRIN).
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);
-- Create a BRIN index with a specified range.
CREATE INDEX [indexname] ON [tablename] USING BRIN ([geometryfield]) WITH (pages_per_range = [number]);

-- Determine whether a spatial geometry object consists of only simple elements.
 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)


-- Query the largest city with roundabouts in the terrain.
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   | Anning        | 257374619.430216
(1 row)

-- Create the bc_roads table. 
Create table bc_roads (gid serial, name varchar, the_geom geometry);

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

-- Compute the length.
SELECT sum(ST_Length(the_geom))/1000 AS km_roads FROM bc_roads;

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

-- Compute the area.
SELECT ST_Area(the_geom)/10000 AS hectares FROM bc_municipality WHERE name = 'PRINCE GEORGE';

hectares
------------------
32657.9103824927
(1 row)
-- Use the ST_Contains function.
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


-- Use the ST_Covers function.
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)    

-- Use the ST_Disjoint function.
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)

-- Use the ST_Overlaps function.
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

-- Use the ST_Relate function.
SELECT ST_Relate(ST_GeometryFromText('POINT(1 2)'), ST_Buffer(ST_GeometryFromText('POINT(1 2)'),2), '0FFFFF212');
St_relate
-----------
t

-- Use the ST_Touches function.
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)

-- Use the ST_Within function.
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)