|Developer(s)||Refractions Research, Paul Ramsey, Dave Blasby, Kevin Neufeld, Mark Cave-Ayland, Regina Obe, Sandro Santilli, Olivier Courtin, Nicklas Avén, Bborie Park, Pierre Racine, Jeff Lounsbury, Chris Hodgson, Jorge Arévalo, Mateusz Loskot, Norman Vine, Carl Anderson, Ralph Mason, Klaus Foerster, Bruno Wolff III, Markus Schaber|
|Initial release||April 19, 2005|
|Stable release||2.1.7 / March 30, 2015|
|Operating system||Linux, Windows, Mac OS X, POSIX-compliant systems|
|Type||Geographic information system|
|License||GNU General Public License (version 2 or later)|
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 (OGC).
In 2006 the OGC registered PostGIS as "implement[ing] the specified standard" for "Simple Features for SQL".
- Geometry types for points, linestrings, polygons, multipoints, multilinestrings, multipolygons and geometrycollections.
- Spatial predicates for determining the interactions of geometries using the 3x3 DE-9IM (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, PostGIS WKT Raster (now integrated into PostGIS 2.0+ and renamed PostGIS Raster)
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.
PostGIS is registered as "implements the specified standard" for "Simple Features for SQL" by the OGC. PostGIS has not been certified as compliant by the OGC. For the OGC's definition of compliant, see What does "Compliant" mean?.
There are a large number of software products that can use PostGIS as a database backend, including:
- ArcGIS (via GISquirrel, ST-Links SpatialKit, ZigGIS, ArcSDE and other third-party connectors)
- Cadcorp SIS
- CitySurf Globe
- ERDAS APOLLO
- Everest GIS
- Feature Manipulation Engine
- GeoMedia (via third-party connectors)
- GRASS GIS (GPL)
- gvSIG (GPL)
- Interoperability Extension from Esri
- Ionic Red Spider
- Kosmo (GPL)
- Manifold System
- MapInfo Professional
- Mapnik (LGPL)
- MapDotNet Server
- MapServer (BSD)
- MapGuide (LGPL)
- Nominatim, which powers the OpenStreetMap website
- OpenJUMP (GPL)
- QGIS (GPL)
- Spatial Manager™
- Skylinesoft TerraExplorer™
- TerraLib (LGPL)
- TerraView (GPL)
- TileMill, 
- uDig (LGPL)
- Uber (company)
- Well-known text and binary, descriptions of geospatial objects used within PostGIS
- PostGIS HTML Documentation.
- PostGIS 2.1.3 PDF Manual.
- PostGIS in Action, 1st edition in hard-copy April 2011, 2nd Edition came out May 2015 from Manning Publications.
- Frank Warmerdam, PostGIS: A Standards Based Geographic Extension for PostgreSQL, presentation at PGCon 2008.