Query events with Pool

With a client we can use the “row” event of a query. client.query("select id from table").on("row", row => console.log(row))

{ id: 1 }
{ id: 2 }
{ id: 3 }
{ id: 4 }
{ id: 5 }

But with a pool we can’t do this. pool.query("select id from table").on("row", row => console.log(row)) TypeError: pool.query(...).on is not a function

Is it possible to use the query events with pool?

[brianc]

The pool supports returning a client if you want to do something like that:

pool.connect(function(err, client, done) {
  var query = client.query('whatever')
  query.on('row', //etc)
  //...etc
})

That API ^^ has existed for years and is still there. 😄

pool.query is a helper method for the most common operation which is “I want to run a query and get the rows back.” If you want to do something “fancier” with a client (transactions, row events, listen/notify, pg-query-stream, etc) then pool.query isn’t for you. I don’t really want to extend the pool.query method with even more functionality…

Curious: why are you using query.on('row') in the first place?

[bluenote10]

If you want to do something “fancier” with a client (transactions, row events, listen/notify, pg-query-stream, etc) then pool.query isn’t for you. I don’t really want to extend the pool.query method with even more functionality…

@brianc Thanks for the clarification, that really makes sense. A quick question about the exact semantics: When using client.on('notification', callback) on a client acquired from a pool, is it safe to release this client back to the pool and still get notify updates, or does this require holding on to the client indefinitely?