PostGres – PostGIS on OSX Lion

I recently just wasted a lot of time trying to get PostGIS up and running on OSX Lion. I wanted to do this so I could pull in Open Street Map data for the DC region and then play with it in QGIS and import it into Tilemill. I will be the first to admit that this is a rather complex toolchain, but it shouldn’t have been as difficult as it was.

On the off chance I can save someone time, I will recap what I did… and some of the misstep.

My big misstep was trying to use the precompiled binaries from KyngChaos. While they work fine, the OSM importer for PostGIS always SegFaulted when I tried running it against these versions. I even tried compiling the importer from source code and couldn’t get it work.

Here is what to do:

1. Use Homebrew. It makes it easy to download and compile source code. You may need to get rid of old cruft you have previously downloaded. I had to remove MacPython and some old Frameworks. If you run “brew doctor” it will give you hints.
2. Install Homebrew
3. Install PostGres, PostGIS and all dependancies: ‘brew install postgis’
4. Initialize the database. This will create a Database structure and a database user (“role”) that is the same as user Mac user name: ‘initdb /usr/local/var/postgres/’
5. Create a database for GIS stuff (Instead of Luke, use your OSX username): ‘createdb -U Luke -E utf8 gis’
6. Start the PostGres server – for some reason I needed to specify that it is running on localhost: ‘postgres -D /usr/local/var/postgres/ -h localhost’
7. Add the PostGIS stuff to the DB: ‘psql -d gis -U Luke -f /usr/local/share/postgis/postgis.sql’ and also ‘psql -d gis -U Luke -f /usr/local/share/postgis/spatial_ref_sys.sql’
8. Awesome! Now you should have a PostGIS DB loaded up. Now time to install the importer: ‘brew install osm2pgsql’
9. It is going to fail. This is because you need to apply a patch to fix some inconsistency. Big pain in the ass. To do that, download the patch from here: http://trac.openstreetmap.org/raw-attachment/ticket/3299/patch-build_geometry.cpp
10. To apply the patch, use the patch command: ‘cd ~/Library/Caches/Homebrew/osm2pgsql–svn/’ and then ‘patch -p0 < ~/Downloads/patch-build_geometry.cpp’
11. Now try it again and it should work: ‘brew install osm2pgsql’
12. Awesome, almost there. Next step is to download some OSM data. Cloudmade makes it pretty easy. I grabbed the DC data from here: http://downloads.cloudmade.com/americas/northern_america/united_states/district_of_columbia#downloads_breadcrumbs
13. Goto where ever you downloaded your files to and run (replacing it with your OSM file): ‘osm2pgsql -U Luke -H localhost -d gis  district_of_columbia.osm’
14. TADA! All that wonderful data should be loaded into your PostGIS DB. Now open up QGIS and add in a PostGIS layer. Make sure you use your OSX Username as the username (Luke) and the PostGIS DB you just created (DB).