Topology Constructors

CreateTopology

Creates a new topology schema and registers it in the topology.topology table.

Synopsis

integer CreateTopology(name  topology_schema_name, integer  srid, double precision  prec, boolean  hasz, integer  topoid, boolean  useslargeids)

Description

Creates a new topology schema with name topology_name and registers it in the topology.topology table. Topologies must be uniquely named. The topology tables (edge_data, face, node,and relation are created in the schema. It returns the id of the topology.

The srid is the spatial reference system SRID for the topology. The SRID defaults to -1 (unknown) if not specified.

The tolerance prec is measured in the units of the spatial reference system. The tolerance defaults to 0.

hasz defaults to false if not specified.

topoid optional explicit identifier (allows deterministic topology id assignment, needs to be unique)

useslargeids optional, defaults to false. If true, the topology will be created to support large ids (int8) for topology and primitive ids.

This is similar to the SQL/MM ST_InitTopoGeo but has more functionality.

Availability: 1.1

Enhanced: 2.0 added the signature accepting hasZ

Examples

Create a topology schema called ma_topo that stores edges and nodes in Massachusetts State Plane-meters (SRID = 26986). The tolerance represents 0.5 meters since the spatial reference system is meter-based.

SELECT topology.CreateTopology('ma_topo', 26986, 0.5);

Create a topology for Rhode Island called ri_topo in spatial reference system State Plane-feet (SRID = 3438)

SELECT topology.CreateTopology('ri_topo', 3438) AS topoid;
topoid
------
2

See Also

Spatial Reference Systems, ST_InitTopoGeo, Topology_Load_Tiger

CopyTopology

Makes a copy of a topology (nodes, edges, faces, layers and TopoGeometries) into a new schema

Synopsis

integer CopyTopology(varchar  existing_topology_name, varchar  new_name)

Description

Creates a new topology with name new_name, with SRID and precision copied from existing_topology_name The nodes, edges and faces in existing_topology_name are copied into the new topology, as well as Layers and their associated TopoGeometries.

Availability: 2.0.0

Examples

Make a backup of a topology called ma_topo.

SELECT topology.CopyTopology('ma_topo', 'ma_topo_backup');

See Also

Spatial Reference Systems, CreateTopology, RenameTopology

ST_InitTopoGeo

Creates a new topology schema and registers it in the topology.topology table.

Synopsis

text ST_InitTopoGeo(varchar  topology_schema_name)

Description

This is the SQL-MM equivalent of CreateTopology. It lacks options for spatial reference system and tolerance. it returns a text description of the topology creation, instead of the topology id.

Availability: 1.1

SQL-MM 3 Topo-Geo and Topo-Net 3: Routine Details: X.3.17

Examples

SELECT topology.ST_InitTopoGeo('topo_schema_to_create') AS topocreation;
                      astopocreation
------------------------------------------------------------
 Topology-Geometry 'topo_schema_to_create' (id:7) created.

See Also

CreateTopology

ST_CreateTopoGeo

Adds a collection of geometries to a given empty topology and returns a message detailing success.

Synopsis

text ST_CreateTopoGeo(varchar  atopology, geometry  acollection)

Description

Adds a collection of geometries to a given empty topology and returns a message detailing success.

Useful for populating an empty topology.

Availability: 2.0

SQL-MM: Topo-Geo and Topo-Net 3: Routine Details -- X.3.18

Examples

-- Populate topology --
SELECT topology.ST_CreateTopoGeo('ri_topo',
 ST_GeomFromText('MULTILINESTRING((384744 236928,384750 236923,384769 236911,384799 236895,384811 236890,384833 236884,
  384844 236882,384866 236881,384879 236883,384954 236898,385087 236932,385117 236938,
  385167 236938,385203 236941,385224 236946,385233 236950,385241 236956,385254 236971,
  385260 236979,385268 236999,385273 237018,385273 237037,385271 237047,385267 237057,
  385225 237125,385210 237144,385192 237161,385167 237192,385162 237202,385159 237214,
  385159 237227,385162 237241,385166 237256,385196 237324,385209 237345,385234 237375,
  385237 237383,385238 237399,385236 237407,385227 237419,385213 237430,385193 237439,
  385174 237451,385170 237455,385169 237460,385171 237475,385181 237503,385190 237521,
  385200 237533,385206 237538,385213 237541,385221 237542,385235 237540,385242 237541,
  385249 237544,385260 237555,385270 237570,385289 237584,385292 237589,385291 237596,385284 237630))',3438)
  );

      st_createtopogeo
----------------------------
 Topology ri_topo populated


-- create tables and topo geometries --
CREATE TABLE ri.roads(gid serial PRIMARY KEY, road_name text);

SELECT topology.AddTopoGeometryColumn('ri_topo', 'ri', 'roads', 'topo', 'LINE');

See Also

TopoGeo_LoadGeometry, AddTopoGeometryColumn, CreateTopology, DropTopology

TopoGeo_AddPoint

Adds a point to an existing topology using a tolerance and possibly splitting an existing edge.

Synopsis

bigint TopoGeo_AddPoint(varchar  atopology, geometry  apoint, float8  tolerance)

Description

Adds a point to an existing topology and returns its identifier. The given point will snap to existing nodes or edges within given tolerance. An existing edge may be split by the snapped point.

Availability: 2.0.0

See Also

TopoGeo_AddLineString, TopoGeo_AddPolygon, TopoGeo_LoadGeometry, AddNode, CreateTopology

TopoGeo_AddLineString

Adds a linestring to an existing topology using a tolerance and possibly splitting existing edges/faces.

Synopsis

SETOF bigint TopoGeo_AddLineString(varchar  atopology, geometry  aline, float8  tolerance)

Description

Adds a linestring to an existing topology and returns a set of signed edge identifiers forming it up (negative identifies mean the edge goes in the opposite direction of the input linestring). The given line will snap to existing nodes or edges within given tolerance. Existing edges and faces may be split by the line. New nodes and faces may be added.

Availability: 2.0.0

Enhanced: 3.2.0 added support for returning signed identifier.

See Also

TopoGeo_AddPoint, TopoGeo_AddPolygon, TopoGeo_LoadGeometry, AddEdge, CreateTopology

TopoGeo_AddPolygon

Adds a polygon to an existing topology using a tolerance and possibly splitting existing edges/faces. Returns face identifiers.

Synopsis

SETOF bigint TopoGeo_AddPolygon(varchar  atopology, geometry  apoly, float8  tolerance)

Description

Adds a polygon to an existing topology and returns a set of face identifiers forming it up. The boundary of the given polygon will snap to existing nodes or edges within given tolerance. Existing edges and faces may be split by the boundary of the new polygon.

Availability: 2.0.0

See Also

TopoGeo_AddPoint, TopoGeo_AddLineString, TopoGeo_LoadGeometry, AddFace, CreateTopology

TopoGeo_LoadGeometry

Load a geometry into an existing topology, snapping and splitting as needed.

Synopsis

void TopoGeo_LoadGeometry(varchar  atopology, geometry  ageom, float8  tolerance)

Description

Loads a geometry into an existing topology. The given geometry will snap to existing nodes or edges within given tolerance. Existing edges and faces may be split as a consequence of the load.

Availability: 3.5.0

See Also

TopoGeo_AddPoint, TopoGeo_AddLineString, TopoGeo_AddPolygon, CreateTopology