Question

Here is my case:
I have a MongoDB collection in Node.Js.

Let’s say three elements: a, b, c I want to insert new element as the first one and want the last one to go out.

So it would be:
d, a, b

In next iteration:
e, d, a

1.How to do that kind of insetion?

2.Is there a chance to listen for those insetions from another node.js app? Something like

collection.on('update', function() {
  console.log('updated');    
});

Answer 1

1. Capped collections in MongoDB preserve insertion order and discard the oldest items based on the total collection size (unfortunately measured in bytes). Seems like ideal fit for your scenario.

2. I believe there is no trigger/notification mechanism in MongoDB yet, only manual polling.