The database scheme we use in german manik style does not use use separate database columns for diffenent tags. Instead only one hstore column is used to provide all important tags (see hstore-only.style osm2pgsql style).
For this reason the osm2pgsql commandline required will look slightly different:
osm2pgsql -S hstore-only.style --hstore --hstore-match-only -d osm planet-latest.osm.pbf -p planet_osm_hstore
You also need to make shure, that the version of osm2pgsql used supports the nocolumn option! This is the case from 0.89 onwards.
The actual rendering is done using database views providing virtual columns instead of using the raw tables generated by osm2pgsql. These views have to be created after the initial osm2pgsql data import using the provides SQL files as follows:
psql -d osm -f osm_tag2num.sql
psql -d osm -f views_osmde/view-line.sql
psql -d osm -f views_osmde/view-point.sql
psql -d osm -f views_osmde/view-polygon.sql
psql -d osm -f views_osmde/view-roads.sql
For compatibility reasons the views are given the same name as the default osm2pgsql tables used in upstream openstreetmap carto style.
The style is currently developed using Debian GNU/Linux 8.x with all the required software (postgresql-9.4, mapnik2.2 node-carto 0.9.5-2, ...) provided by the distribution itself. Using Ubuntu >=14.4 should also work.
To get this style running it is also required to add the l10n code to the postgresql database.
If l10n is not needed it is also possible to slightly modify either project.yaml or the database views provided in views_osmde directory.