9.1 Representing Spatial Data in a Property Graph

Spatial data can be used as values of vertex properties and edge properties.

For example, an entity can have a point (longitude/latitude) as the value of a property named location. As another example, an edge may have a polygon as the value of a property, and this property can represent the location at which this link (relationship) was established.

The following shows some example syntax for encoding spatial data in a property graph.

• Point: '-122.230 37.560'

• Point: 'POINT(-122.241 37.567)'

• Point with SRID specified: 'srid/8307 POINT(-122.246 37.572)'

• Polygon: 'POLYGON((-83.6  34.1, -83.6 34.3, -83.4 34.3, -83.4 34.1, -83.6 34.1))'

• Polygon with SRID specified: 'srid/8307 POLYGON((-83.6 34.1, -83.6 34.3, -83.4 34.3, -83.4 34.1, -83.6 34.1))'

• Line string: 'LINESTRING (30 10, 10 30, 40 40)'

• Multiline string: 'MULTILINESTRING ((10 10, 20 20, 10 40), (40 40, 30 30, 40 20, 30 10))'

Assume a test property graph named test. The following statements add a set of vertices with coordinates (longitude and latitude) spacified for each.

insert into testVT$(vid, k, t, v) values(100, 'geoloc', 20, '-122.230 37.560'); 
insert into testVT$(vid, k, t, v) values(101, 'geoloc', 20, '-122.231 37.561');
insert into testVT$(vid, k, t, v) values(102, 'geoloc', 20, '-122.236 37.562914');
insert into testVT$(vid, k, t, v) values(103, 'geoloc', 20, '-122.241 37.567');
insert into testVT$(vid, k, t, v) values(104, 'geoloc', 20, '-122.246 37.572');
insert into testVT$(vid, k, t, v) values(105, 'geoloc', 20, '-122.251 37.577');
insert into testVT$(vid, k, t, v) values(200, 'geoloc', 20, '-122.256 37.582');
insert into testVT$(vid, k, t, v) values(201, 'geoloc', 20, '-122.261 37.587');

The Spatial data in the property graph can be used to construct SDO_GEOMETRY objects. For example, the OPG_APIS.GET_GEOMETRY_FROM_V_T_COLS function can be used to read spatial data from the V column for all T of a specified value (such as 20), and return SDO_GEOMETRY objects. This function attempts to parse the value as coordinates if the value appears to be two numbers, and it uses the SDO_GEOMETRY constructor if the value is not a simple point. Finally, if a SRID is provided, it uses the SDO_CS_TRANSFORM procedure to transform using the given coordinate system.

The following example uses the OPG_APIS.GET_GEOMETRY_FROM_V_T_COLS function to get geometries from the test property graph. It includes some of the output.

SQL> select vid, k, opg_apis.get_geometry_from_v_t_cols 
      from testVT$     
        order by vid, k;
   . . .
       100 geoloc SDO_GEOMETRY(2001, 8307, SDO_POINT_TYPE(-122.23, 37.56, NULL), NULL, NULL)
       101 geoloc SDO_GEOMETRY(2001, 8307, SDO_POINT_TYPE(-122.231, 37.561, NULL), NULL, NULL)
       102 geoloc SDO_GEOMETRY(2001, 8307, SDO_POINT_TYPE(-122.236, 37.562914, NULL), NULL, NULL)
       103 geoloc SDO_GEOMETRY(2001, 8307, SDO_POINT_TYPE(-122.241, 37.567, NULL), NULL, NULL)
   . . .

You can generate SDO_GEOMETRY objects from WKT literals.  The following example inserts WKT literals, and then uses the OPG_APIS.GET_WKTGEOMETRY_FROM_V_T_COLS function to construct SDO_GEOMETRY objects from the V, T columns.

truncate table testGE$;
truncate table testVT$;
insert into testVT$(vid, k, t, v) values(101, 'geoloc', 20, 'POLYGON((-83.6  34.1, -83.6 34.3, -83.4 34.3, -83.4 34.1, -83.6 34.1))');
insert into testVT$(vid, k, t, v) values(103, 'geoloc', 20, 'POINT(-122.241 37.567)');
insert into testVT$(vid, k, t, v) values(105, 'geoloc', 20, 'POINT(-122.251 37.577)');
insert into testVT$(vid, k, t, v) values(200, 'geoloc', 20, 'MULTILINESTRING ((10 10, 20 20, 10 40), (40 40, 30 30, 40 20, 30 10))');
insert into testVT$(vid, k, t, v) values(201, 'geoloc', 20, 'LINESTRING (30 10, 10 30, 40 40)');

prompt show the geometry info
SQL> select vid, k, opg_apis.get_wktgeometry_from_v_t_cols(v,t) 
       from testVT$
      order by vid, k;
   . . .
       101 geoloc SDO_GEOMETRY(2003, 8307, NULL, SDO_ELEM_INFO_ARRAY(1, 1003, 1), SDO_ORDINATE_ARRAY(-83.6, 34.1, -83.6, 34.3, -83.4, 34.3, -83.4, 34.1, -83.6, 34.1))
       103 geoloc SDO_GEOMETRY(2001, 8307, SDO_POINT_TYPE(-122.241, 37.567, NULL), NULL, NULL)
       105 geoloc SDO_GEOMETRY(2001, 8307, SDO_POINT_TYPE(-122.251, 37.577, NULL), NULL, NULL)
       200 geoloc SDO_GEOMETRY(2006, 8307, NULL, SDO_ELEM_INFO_ARRAY(1, 2, 1, 7, 2, 1), SDO_ORDINATE_ARRAY(10, 10, 20, 20, 10, 40, 40, 40, 30, 30, 40, 20, 30, 10))
       201 geoloc SDO_GEOMETRY(2002, 8307, NULL, SDO_ELEM_INFO_ARRAY(1, 2, 1), SDO_ORDINATE_ARRAY(30, 10, 10, 30, 40, 40))