Although it is usually preferable to stick with stable releases of PostGIS for production databases, there are good reasons to use recent development versions for raster processing.
Compiling from source on Ubuntu is quick and painless using default settings, providing all the libraries are available.
sudo add-apt-repository ppa:ubuntugis/ubuntugis-unstable sudo apt-get update sudo apt-get -y install proj.dev libgdal.dev sudo apt-get install libgdal.dev libproj.dev libxml2-dev libgeos-dev sudo apt-get install libarmadillo-dev libpoppler-dev libepsilon-dev libexpat-dev liblzma-dev
wget http://postgis.net/stuff/postgis-2.2.0dev.tar.gz tar xvzf postgis-2.2.0*tar.gz cd postgis*dev ./configure make sudo make install
The loaders are compiled and just need installing.
cd postgis*dev*/loader sudo make install cd .. cd .. cd postgis*dev*/raster/loader sudo make install
PLR can also be compiled from source.
wget https://github.com/jconway/plr/archive/master.zip unzip master.zip cd plr-master USE_PGXS=1 make sudo USE_PGXS=1 make install
Now to update a data base into which PostGIS has been installed though the extension mechanism
ALTER EXTENSION postgis UPDATE TO '2.2.0'; ALTER EXTENSION postgis_topology UPDATE TO '2.2.0';
If this does not work, for example if you have a database that installed PostGIS using the older SQL route, then you can upgrade through the backup and restore mechanism.
For example, to update a database called “reddeam”.
sudo -u postgres pg_dump reddeam > reddeam.backup dropdb reddeam createdb reddeam psql -d reddeam -c "CREATE EXTENSION postgis;" psql -d reddeam -c "CREATE EXTENSION postgis_topology;" sudo -u postgres psql reddeam<reddeam.backup
You may need to add support for legacy functions if you used them.
More advise is avalailable here.