Some numbers do not arrive complete. A figure for yesterday can look different tomorrow, because late information keeps landing for days. If you overwrite it each time, you lose the one thing that explains why last week's report disagrees with this week's.
Append, do not replace
For anything that can be revised, we keep every version and mark which one is current:
- the latest value is what dashboards show,
- the earlier ones stay, with when we saw them,
- and a short note records why something changed when we know.
This turns a confusing "the number moved" into a question we can answer.
Where we use it
- Store listings: the text we ship and the text we proposed.
- Config: what a game shipped with, per version.
- Reports from external services: re-reading a period corrects it without double counting.
Know what a number is not
Part of the discipline is writing down what each source cannot tell you. A report with no denominator cannot give you a rate; a count of unique devices must never be summed. Notes like these live next to the data, so the next person does not draw a confident conclusion from the wrong column.
The cost
More rows, and a rule that "current" is a query rather than a field. It is a small price. The first time a number surprises us and the history explains it in a minute, it has paid for itself.
