GRASS-PostGIS data provider

Table of Contents

• Introduction
• List of functions
• See Also
• Authors

by GRASS Development Team (https://grass.osgeo.org)

Introduction

GRASS-PostGIS data provider allows GRASS vector library to read and write PostGIS data directly without any external library (like in the case of GRASS-OGR data provider). GRASS-PostGIS data provider is implemented using libpq library.

Note that GRASS-PostGIS data provider is compiled only when GRASS is configured with –with-postgres switch.

See the trac page for more info.

List of functions

Note that the functions listed below are lower level subroutines, in other word these functions are not considered to be part of public API. They are internally used by the vector library when accessing PostGIS data. The programmer should use higher level functions instead.

• Vect_open_old() to open existing vector map (ie. PostGIS table when using GRASS-PostGIS data provider)
• Vect_open_new() to create new vector map
• Vect_close() to close vector map
• Vect_rewind() to rewind the map for sequential access
• Vect_read_next_line() for sequential access
• Vect_read_line() for random access
• Vect_write_line() to write a new feature
• Vect_delete_line() to delete existing feature
• Vect_rewrite_line() to modify existing feature
• Vect_build() to build (pseudo-)topology

Note that functions with V1_ prefix access vector data without topology. Topological (pseudo-topological for simple features) access is provided by functions starting with V2_ prefix.

Open/Create PostGIS table as GRASS vector map

• V1_open_old_pg()
• V2_open_old_pg()
• V1_open_new_pg()
• V1_close_pg()
• V2_close_pg()

Read access

• V1_rewind_pg()
• V2_rewind_pg()
• V1_read_next_line_pg()
• V2_read_next_line_pg()
• V1_read_line_pg()
• V2_read_line_sfa()
• V2_read_line_pg()

Write new feature or topological element

• V1_write_line_pg()
• V2_write_line_sfa() - write new simple feature
• V2_write_line_pg() - write new topological element in PostGIS Topology schema

Delete existing feature or topological element

• V1_delete_line_pg()
• V2_delete_line_sfa() - delete simple feature
• V2_delete_line_pg() - delete topological element from PostGIS Topology schema

Modify existing feature or topological element

• V1_rewrite_line_pg()
• V2_rewrite_line_sfa() - modify simple feature
• V2_rewrite_line_pg() - modify topological element from PostGIS Topology schema

Build topology

• Vect_open_topo_pg()
• Vect__build_sfa()
• Vect_build_pg()

See Also

• GRASS-OGR data provider

Authors

Martin Landa <landa.martin gmail.com>