Track · 2:30 · Liner note
The Past, Kept Warm
A history table keeps every earlier version of a row along with the period it was valid, so you can query what the data looked like on any past date.
Ask what a customer’s plan was in March, and most tables can only tell you what it is now. A history table keeps each earlier version of a row with the period it applied, so as-of queries work. The Past, Kept Warm is that archive, reachable instead of buried in cold storage.
Design it with a valid-from and valid-to pair, close the old version in the same transaction that writes the new one and index for lookups by key and date. Then test with a record edited back and forth, because the gaps hide there.