Merge Shapes

- DL data as GeoJSON from ODS
- $ ogr2ogr -f "ESRI Shapefile" foo.shp foo.geojson OGRGeoJSON
- $ shp2pgsql foo.shp foo > foo.sql
- $ createdb gp
- $ psql -d gp
- gp=# CREATE EXTENSION postgis;
- $ psql -f foo.sql -d gp
- gp=# create table merged as
	select id, ST_Union(geom)
	from foo
	group by id;
- gp=# \copy (select id, ST_AsGeoJSON(st_union) from merged) TO '~/Downloads/export.csv' CSV HEADER