Oplog tailing in Meteor - to do it or not to do it?

Question

I am trying to reconcile this kadira.io article which says that oplog tailing is a must for every Meteor production app with this compose.io article - see section "To Oplog or not Oplog" which says you should only use oplog in certain circumstances.

Basically I have a Meteor app which does not have a high volume of users or a massive amount of continuous writing to collections.

It does however need to read a lot of data from the DB which seems to be slowing things down.

As far as I know it is only running on one server.

I am wondering will adding oplog tailing speed things up?

Thanks in advance.

Answer 1

Basically no matter if you do it, replica set is always doing it to keep all nodes in sync. Usually if your system is not write heavy, the tailing shouldn't be an issue because with replication working, the latest oplog should be in memory. What causes stress is usually the first round when the program tries to find where to tail from. With no index, it has to be a COLLSCAN. Other than that there's no need to worry. But it's a one time thing so as long as you know what's going on, it should be fine.

Back to your question. Yes it's running on one server. Which one depends on your readPreference and replica set tag if any. And after the first time finding the tail point, it shouldn't be a problem.