Update ETL docs

etl/README.md

@@ -12,16 +12,40 @@ Before running any of these scripts, you will need the OS data for your area of
 interest. AddressBase and MasterMap are available directly from [Ordnance
 Survey](https://www.ordnancesurvey.co.uk/).
 
-To help test the Colouring London app, `get_test_polygons.py` will attempt to save a small
-(1.5km²) extract from OpenStreetMap to a format suitable for loading to the database.
-
 The scripts should be run in the following order:
 
-1. extract_addressbase.sh
-1. extract_mastermap.sh
-1. filter_transform_mastermap_for_loading.sh
-1. load_geometries.sh
-1. create_building_records.sh
-1. (SQL migration) psql < ../migrations/002.index-geometries.sql
-1. load_uprns.py
-1. (SQL migration) psql < ../migrations/002.index-buildings.sql
+```bash
+# extract both datasets
+extract_addressbase.sh ./addressbase_dir
+extract_mastermap.sh ./mastermap_dir
+# filter mastermap ('building' polygons and any others referenced by addressbase)
+filter_transform_mastermap_for_loading.sh ./addressbase_dir ./mastermap_dir
+# load all building outlines
+load_geometries.sh ./mastermap_dir
+# index geometries (should be faster after loading)
+psql < ../migrations/002.index-geometries.sql
+# create a building record per outline
+create_building_records.sh
+# add UPRNs where they match
+load_uprns.py ./addressbase_dir
+# index building records
+psql < ../migrations/002.index-buildings.sql
+```
+
+To help test the Colouring London application, `get_test_polygons.py` will attempt to save a
+small (1.5km²) extract from OpenStreetMap to a format suitable for loading to the database.
+
+In this case, run:
+
+```bash
+# download test data
+get_test_polygons.py
+# load all building outlines
+load_geometries.sh ./test_data_dir
+# index geometries (should be faster after loading)
+psql < ../migrations/002.index-geometries.sql
+# create a building record per outline
+create_building_records.sh
+# index building records
+psql < ../migrations/002.index-buildings.sql
+```