Automations: when this happens, do that — What a rehearsal can’t know

Anything the replay can’t be sure about is printed under the numbers, headed What this cannot know — it is worth reading, because the whole point is to be able to trust the figure. The usual ones: a field kept out of history leaves no trace to replay, so a condition on it is judged against the value the record holds today. Conditions on lookup, rollup and formula fields are the same — those are computed from other records, and what those records held at the time was never recorded anywhere. Records deleted for good since then can’t be rebuilt at all. One note can push the real number up rather than down: if the rule writes back to the same table, a real run would have produced changes of its own, which could have set this or another rule off again. The rehearsal only sees changes that actually happened. Very busy tables are capped, and when that happens the panel says which date the figures really start from rather than quietly reporting a short count.