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UK Explr Usage

Overview

There are two parts to UK Explr:

  1. To create a database from raw data files. See: Initialise Database.

  2. To serve the data through a REST API endpoint. See: Serve Query API.

Getting Started

  1. Create .env file in project root directory based on .env.example.

Initialise Database

  1. Optional. Clear the existing database, if any:

    npm run uninit

  2. Initialise the new database:

    npm run init

  3. Start the migration:

    npm run migrate

Serve Query API

  1. Start the web server:

    npm run serve

  2. Make GET request(s) to route: /v1/query-result

    Note that:

    • The query string is parsed to using the qs package.

    • Query parameters are described by the QueryRequest schema object.

Troubleshooting

Stuck at Updating lookup table...

This is due to Postgres not unlocking the lookup table due to a race condition.

To resolve this issue, first cancel execution of the migration script (using the Control + C keys).

Next, find the process that has locked the table using the command:

lsof -i :<value of PG_PORT in env file>

You should first check the machine from which the migration script is executed (this will likely be a node process).

If no process can be found on the machine from which the migration script is executed, then check the machine hosting the Postgres database (this will likely be a postgres process that is NOT the database server, but represents a network connection to the database).

Once the process is identified, kill the process:

kill -9 <identified process id>

where -9 corresponds to SIGKILL

It might take more than one attempt to kill the process; when the process is killed, the command should print: no such process.

You can now rerun the migration script.