What is the best way to look for latest transaction_id for a given original_transaction_id?

We have been using the purchase date to identify the latest transaction_id for a given original_transaction_id. However, I’ve noticed several cases where an immediate upgrade does not result in a later purchase date—in some instances, it is actually earlier than the previous transaction.

Given this inconsistency, would it be more reliable to sort by transaction_id in descending order instead?

What is the best way to look for latest transaction_id for a given original_transaction_id?
 
 
Q