I have a Data-Driven Alert set to "Once - the first time it's true", watching a % Usage measure against an 80% threshold. The underlying calculation is tied to a rolling 12-month contract period (Aug 1–Jul 31) that resets automatically each year via TODAY()-based calculated fields — so % Usage climbs from 0% at the start of each contract year, and may or may not cross 80% before the year ends.
Example scenario:
- Contract Year 1: Aug 2026–Jul 2027. Usage crosses 80% in March 2027 → alert fires, one email sent.
- Aug 2027: new contract year begins, % Usage resets to ~0% (condition goes back to false).
- Contract Year 2: usage climbs again and crosses 80% in April 2028.
Question: In Year 2, once the condition goes false (Aug 2027) and then becomes true again (April 2028), will the alert fire again? Or does "Once - the first time it's true" mean the alert only ever sends a single email for the lifetime of that alert, regardless of the condition later resetting and re-triggering?
I haven't been able to find documentation that's explicit about whether "Once" re-arms on a false→true transition, or whether it's a one-shot for the alert's entire existence. Has anyone tested this across a reset cycle, or does Tableau document this behavior anywhere? Trying to decide whether I need to manually recreate the alert each year or whether it'll keep working unattended.
Tableau version: 2024.2.4
#Tableau Server
Hi, yeah I know it is confusing, but the option comes with the rearm condition.
However, it worths to mention that there are two important things:
a. When alerts are evaluated: When using extracts, after each extract refresh. When using live query every 60 minutes. This means, your rearm condition when selecting the "Once..." option will be evaluated following this interval.
b. When alerts are sent:
If the option is "Once ..." and the condition is met, then sent. It will never be sent again until "rearm".
The first time the condition is met -> Sent
If the alert is evaluated according to an interval:
The first time alert is true -> Sent.
This starts a cycle, according to the frequency you have chosen (hourly, daily, weekly), if condition remains true -> Sent. If condition is not met -> Not sent (Rearm).
If this post resolves the question, would you be so kind to "Accept this Answer"?. This will help other users find the same answer/resolution and help community keep track of answered questions. Thank you.
Regards,
Diego Martinez
Tableau Visionary and Tableau Ambassador
