UPDATE: Since this article was written, Yum now comes packaged with PostGIS 1.5. Please refer to PostGIS Yum Install for PostgreSQL 9.0 if you want to go with a faster more idiot proof install process
A couple of people have asked this, so thought we would address the common issues people run into
with compiling PostGIS.
The first question, some will ask is Why don't you just take the packaged PostGIS that comes with the PostgreSQL
There are two reasons for not installing PostGIS under using Yum and our general reasons for not.
We like running a newer GEOS than what is generally packaged with Yum because certain PostGIS functionality
is not enabled with older versions of GEOS. For example GEOS 3.1 introduced a couple of new functions like ST_Covers and
the Cascaded Union and prepared geometry speed enhancements require GEOS 3.1+. GEOS 3.2 brought more robust support for dealing with topological
exceptions, new buffering features like one-sided buffer (which the upcoming PostGIS 1.5 exposes if and only if you are running
GEOS 3.2+), faster buffering, and several memory leak cleanups. We highly recommend using GEOS 3.2.0. It is just a more robust product than prior GEOS versions.
We generally like to run newer versions of PostGIS than what Yum provides and also run multiple versions of PostGIS
on the same server. This is a bit tricky to do with Yum since it only exposes one and generally an older one than what we
care for. PostGIS 1.5 will be especially great since it will have the geodetic support and cool functions like ST_ClosestPoint
and other major goodies.
NOTE: PostGIS 1.3, PostGIS 1.4, PostGIS 1.5 can coexist on the same PostgreSQL daemon service as long as they are installed in different databases. They will all share the same Proj and GEOS. So installing PostGIS 1.5 will not break your
PostGIS 1.4 or 1.3 installs. The newer GEOS 3.2.0 C-API is backward compatible with older GEOS C-API and the C-API is what PostGIS uses.