v.build.pg - GRASS GIS manual

Note: This document is for an older version of GRASS GIS that has been discontinued. You should upgrade, and read the current manual page.

NAME

v.build.pg - Builds PostGIS topology for vector map linked via v.external.

KEYWORDS

vector, external, PostGIS, topology

SYNOPSIS

v.build.pg

v.build.pg --help

v.build.pg [-p] map=name [topo_schema=name] topo_column=name [tolerance=float] [--overwrite] [--help] [--verbose] [--quiet] [--ui]

Flags:

-p: Don't execute SQL statements, just print them and exit
--overwrite: Allow output files to overwrite existing files
--help: Print usage summary
--verbose: Verbose module output
--quiet: Quiet module output
--ui: Force launching GUI dialog

Parameters:

map=name [required]: Name of vector map
topo_schema=name: Name of schema where to build PostGIS topology; Default: topo_<map>
topo_column=name [required]: Name of topology column; Default: topo
tolerance=float: Tolerance to snap input geometry to existing primitives; Default: 1

DESCRIPTION
NOTES
EXAMPLES
- Workflow example
- Dry run
SEE ALSO
AUTHOR

DESCRIPTION

v.build.pg builds PostGIS topology for feature tables linked via v.external.

NOTES

Note that PostGIS Topology extension is currently under development. v.build.pg requires PostGIS 2.0.0+.

Existing PostGIS topology schema can be overwrite by --overwrite flag.

v.build.pg calls PostGIS functions:

CreateTopology() to create topology schema in the database,
AddTopoGeometryColumn() to add a topogeometry column to an existing feature table, and
toTopoGeom() to create a new topo geometry from the simple feature geometry.

EXAMPLES

Workflow example

Export vector map into PostGIS:

v.out.ogr input=bridges output=PG:dbname=pgis_nc format=PostgreSQL

Create a new vector map as a link to PostGIS table:

v.external input=PG:dbname=pgis_nc layer=bridges

Check metadata:

v.info map=bridges

...
 |----------------------------------------------------------------------------|
 | Map format:      PostGIS (PostgreSQL)                                      |
 | DB table:        public.bridges                                            |
 | DB name:         pgis_nc                                                   |
 | Geometry column: wkb_geometry                                              |
 | Feature type:    point                                                     |
 |----------------------------------------------------------------------------|
...

Build PostGIS topology for the link:

v.build.pg map=bridges

...
Topology topo_bridges (6), SRID 900914, precision 1
10938 nodes, 0 edges, 0 faces, 10938 topogeoms in 1 layers
Layer 1, type Puntal (1), 10938 topogeoms
 Deploy: public.bridges.topo
...

Dry run

For testing issues use -p flag.

v.build.pg map=bridges

Creating new topology schema...

SELECT topology.createtopology('topo_bridges', \
find_srid('public', 'bridges', 'wkb_geometry'), 1)

Adding new topology column...

SELECT topology.AddTopoGeometryColumn('topo_bridges', \
'public', 'bridges', 'topo', 'point')

Building PostGIS topology...

UPDATE bridges SET topo = topology.toTopoGeom(wkb_geometry, \
'topo_bridges', 1, 1)


SELECT topology.TopologySummary('topo_bridges')

AUTHOR

Martin Landa, Czech Technical University in Prague, Czech Republic

SOURCE CODE

Available at: v.build.pg source code (history)

Latest change: Tuesday Feb 17 14:54:26 2026 in commit: 051b9c19442e746e2b51f9c5382809a45230b4c0