111 lines
3.9 KiB
Markdown
111 lines
3.9 KiB
Markdown
# Creating a Colouring London database from scratch
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## Data downloading
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The scripts in this directory are used to extract, transform and load (ETL) the core datasets
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for Colouring London:
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Building geometries, sourced from Ordnance Survey (OS) MasterMap (Topography Layer)
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To get the required datasets, you'll need to complete the following steps:
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1. Sign up for the Ordnance Survey [Data Exploration License](https://www.ordnancesurvey.co.uk/business-government/licensing-agreements/data-exploration-sign-up). You should receive an e-mail with a link to log in to the platform (this could take up to a week).
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2. Navigate to https://orders.ordnancesurvey.co.uk/orders and click the button for: ✏️ Order. From here you should be able to click another button to add a product.
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3. Drop a rectangle or Polygon over London and make the following selections, clicking the "Add to basket" button for each:
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<p></p>
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4. You should be then able to check out your basket and download the files. Note: there may be multiple `.zip` files to download for MasterMap due to the size of the dataset.
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6. Unzip the MasterMap `.zip` files and move all the `.gz` files from each to a single folder in a convenient location. We will use this folder in later steps.
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## Prerequisites
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You should already have set up PostgreSQL and created a database. Make sure to create environment variables to use `psql` if you haven't already:
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```bash
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export PGPASSWORD=<pgpassword>
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export PGUSER=<username>
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export PGHOST=localhost
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export PGDATABASE=<colouringlondondb>
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```
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Create the core database tables:
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```bash
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cd ~/colouring-london
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psql < migrations/001.core.up.sql
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```
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There is some performance benefit to creating indexes after bulk loading data.
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Otherwise, it's fine to run all the migrations at this point and skip the index
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creation steps below.
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Install GNU parallel, this is used to speed up loading bulk data.
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## Make data available to Ubuntu
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If you didn't download the OS files to the Ubuntu machine where you are setting up your Colouring London application, you will need to make them available there. If you are using Virtualbox, you could host share a the folder containing the MasteerMap files with the VM via a shared folder (e.g. [see these instructions for Mac](https://medium.com/macoclock/share-folder-between-macos-and-ubuntu-4ce84fb5c1ad)).
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## Process and load Ordnance Survey data
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Move into the `etl` directory and set execute permission on all scripts.
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```bash
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cd ~/colouring-london/etl
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chmod +x *.sh
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```
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Extract the MasterMap data (this step could take a while).
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```bash
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sudo ./extract_mastermap.sh /path/to/mastermap_dir
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```
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<!-- Note: I removed sudo here before because I addd the chmod +x above - now have had to re-add it, unsure why/ what changed -->
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<!-- Didn't throw an error - did Ctrl-C after an hour, so I then ran: `sudo rm ~/map_data/*.gml` -->
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Filter MasterMap 'building' polygons.
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```bash
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sudo ./filter_transform_mastermap_for_loading.sh /path/to/mastermap_dir
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```
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<!-- Didn't throw an error - did Ctrl-C after a miniute -->
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Load all building outlines. Note: you should ensure that `mastermap_dir` has permissions that will allow the linux `find` command to work without using sudo.
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```bash
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./load_geometries.sh /path/to/mastermap_dir
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```
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Index geometries.
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```bash
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psql < ../migrations/002.index-geometries.up.sql
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```
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<!-- TODO: Drop outside limit. -->
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<!-- But what is the boundary file? -->
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<!-- ```bash
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./drop_outside_limit.sh /path/to/boundary_file
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```` -->
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Create a building record per outline.
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```bash
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./create_building_records.sh
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```
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Run the remaining migrations in `../migrations` to create the rest of the database structure.
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```bash
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ls ~/colouring-london/migrations/*.up.sql 2>/dev/null | while read -r migration; do psql < $migration; done;
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```
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# [WIP] Updating the Colouring London database with new OS data
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TODO: this section should instruct how to update and existing db |