// npm install pg
// bootstrap : psql -h localhost test test
// create table config(id serial, conf json);
// insert into config (conf) values ('{"test": 42}'::json);

var pg = require('pg');
var Pool = pg.Pool;

var pool = new Pool({
  user: 'test',
  host: 'localhost',
  database: 'test',
  password: 'test',
  port: 5432,
})

pool.connect()
  .then(function(client) {
    client.query('LISTEN test_event')

    client.on('notification', function(message) {
      console.log('Got event=', message)
    })

    return client.query({text: 'select * from config'})
      .then(function(res) {
        console.log('Got res=', res.rows[0]);
        client.query("NOTIFY test_event, '" + JSON.stringify(res.rows[0].conf) + "'")
      })
      .catch(function(error) {
        console.log('Got error=', error);
      })
  })
  .catch(function(error) {
    console.log('Pool error=', error)
  })