How can I find out which version of PostGIS I have?
Since some of the functions depend on other libraries like GEOS and proj4 you might want to get their versions too. Then use:
SELECT PostGIS_full_version();
PostGIS_Lib_Version();
- returns the version number of the PostGIS library.
http://postgis.refractions.net/docs/PostGIS_Lib_Version.html
Did you try using SELECT PostGIS_version();
Other way to get the minor version is:
SELECT extversion
FROM pg_catalog.pg_extension
WHERE extname='postgis'
As the above people stated, select PostGIS_full_version(); will answer your question. On my machine, where I'm running PostGIS 2.0 from trunk, I get the following output:
postgres=# select PostGIS_full_version();
postgis_full_version
-------------------------------------------------------------------------------------------------------------------------------------------------------
POSTGIS="2.0.0alpha4SVN" GEOS="3.3.2-CAPI-1.7.2" PROJ="Rel. 4.7.1, 23 September 2009" GDAL="GDAL 1.8.1, released 2011/07/09" LIBXML="2.7.3" USE_STATS
(1 row)
You do need to care about the versions of PROJ and GEOS that are included if you didn't install an all-inclusive package - in particular, there's some brokenness in GEOS prior to 3.3.2 (as noted in the postgis 2.0 manual) in dealing with geometry validity.