PostGIS

PostGIS (/post'-jis/) is an open source software program that adds support for geographic objects to the PostgreSQL object-relational database. PostGIS follows the Simple Features for SQL specification from the Open Geospatial Consortium. As such, PostGIS includes:


 * Geometry types for points, linestrings, polygons, multipoints, multilinestrings, multipolygons and geometrycollections.
 * Spatial predicates for determining the interactions of geometries using the 3x3 Egenhofer matrix (provided by the GEOS software library).
 * Spatial operators for determining geospatial measurements like area, distance, length and perimeter.
 * Spatial operators for determining geospatial set operations, like union, difference, symmetric difference and buffers (provided by GEOS).
 * R-tree-over-GiST (Generalised Search Tree) spatial indexes for high speed spatial querying.
 * Index selectivity support, to provide high performance query plans for mixed spatial/non-spatial queries.
 * For raster data, under development for dealing with WKTRaster

The PostGIS implementation is based on "light-weight" geometries and indexes optimized to reduce disk and memory footprint. Using light-weight geometries helps servers increase the amount of data migrated up from physical disk storage into RAM, improving query performance substantially.

The first version was released in 2001 by Refractions Research under the GNU General Public License. A stable "1.0" version was released on April 19, 2005, which followed 6 release candidates. In 2006, PostGIS was certified as a compliant Simple Features for SQL database by the Open Geospatial Consortium.

There are a large number of software products that can use PostGIS as a database backend, including:


 * Cadcorp SIS
 * ST-Links SpatialKit
 * Feature Manipulation Engine
 * GeoServer
 * GRASS GIS (GPL)
 * gvSIG (GPL)
 * Interoperability Extension from ESRI
 * Ionic Red Spider
 * Kosmo (GPL)
 * Manifold System
 * Mapnik (LGPL)
 * MapDotNet Server
 * MapServer (BSD)
 * MapGuide (LGPL)
 * MezoGIS
 * OpenJUMP (GPL)
 * Quantum GIS (GPL)
 * TerraLib (LGPL)
 * TerraView (GPL)
 * uDig (LGPL)
 * ArcGIS (via ST-Links, ZigGIS, ArcSDE and other 3rd party connectors)

History
See http://www.refractions.net/products/postgis/history/

Reference Book

 * PostGIS in Action, 2010 from Manning.