I am trying to determine the most efficient way to keep a user's rep_change history updated and need some guidance.

Here are a few assumptions that I am inferring from the available information:

 1. the key for rep_change is `post_id` and `user_id` along with an implied site id
 2. the `on_date` field is bumped when a rep related event for that `post_id` occurs

So, if I initialize a rep table with the user's complete rep history and save the time of the update, I can subsequently query `/users/{id}/reputation` with a `fromdate` equal to the last update and the results will contain all items that have had a rep change since `fromdate` - even if they have been returned in a previous update.

i.e. 

- post #10 got a few upvotes when created last year and was entered into my local rep table at that time.
- the past xx number of rep updates have not contained that postid
- today, someone found post #10 and upvoted it and the `on_date` and `positive_rep` are updated
- the next time I query rep post #10 will be in the results and I can update the rep table using `post_id` (and user_id and contrived site_id) as key

Is this an accurate description?