Absolute certainty is challenging with a cost-based optimizer in the mix. DDB doesn't face this challenge. Although, cost for some query patterns in DDB would shift into your application layer - so you may not have exactly the cost certainty you imagine?
Would you be willing to pay more for certainty? E.g. rent the full server at peak + 20% and run at 15% utilization some of the time? Provisioned capacity or pre-committed spend seem like reasonable, but perhaps more costly, ways to get certainty.
Would you be willing to pay more for certainty? E.g. rent the full server at peak + 20% and run at 15% utilization some of the time? Provisioned capacity or pre-committed spend seem like reasonable, but perhaps more costly, ways to get certainty.