Question

The Scenario

Update: It was brought to my attention that ordering by created_at will actually compare a millisecond float that’s of sufficient resolution (by far). However, while I feel a bit dumb now, my question still stands. My scenario is just irrelevant, so I removed it.

The Question

I know that the database knows precisely the order of creation by tracking a row’s ID.

Are there any pitfalls in relying on latest ID to determine order?

Answer 1

A better solution is to replace the latest_post_at with something more precise than a second. Time.now.to_f instead of .to_i will give you sub-second precision (millisecond I think, the docs aren’t clear). Should two posts happen to have the same millisecond timestamp you could use the id as a tie-breaker.