LISTEN query timeout with node-postgres?

Question

I have an \"article\" table on a Postgresql 9.1 database and a trigger that notifies a channel on each insert.

I\'d like to create a node.js script that catches those in

Answer 1

LISTEN is supposed to last for the session lifetime or until you do UNLISTEN. So, as long as your code is running, notifications should be delivered. Note, that IIRC, postgresql gives no promises to deliver one notification per NOTIFY — if you have many inserts it may choose to deliver a single NOTIFY. Not sure about 9.1, they introduced LISTEN payload, so it may make a bit less sense.

Answer 2

I got answer to my issue on the node-postgres repo. To quote Brianc:

pg.connect is use to create pooled connections. Using a connection pool connection for listen events really isn't supported or a good idea though. [...] To 'listen' a connection by definition must stay open permanently. For a connection to stay open permanently it can never be returned to the connection pool.

The correct way to listen in this case is to use a standalone client:

var pg = require ('pg'),
    pgConnectionString = "postgres://user:pass@localhost/db";

var client = new pg.Client(pgConnectionString);
client.connect();
client.query('LISTEN "article_watcher"');
client.on('notification', function(data) {
    console.log(data.payload);
});