Sum Check FAQ
Answers to common questions about how Sum computes the total, why the comparison is exact, and how the anomaly is reported, grouped by topic.
Behavior
Is the comparison exact, or is there a tolerance?
Exact. The computed total must equal the configured value with no margin. For a comparison with an operator or a tolerance, use Aggregation Comparison.
How are empty values treated?
They contribute nothing to the total, exactly like a zero, so the rule cannot distinguish a missing value from a zero. Add Not Null when the difference matters.
Which rows are added up?
Every row that passes the filter clause. Without a filter, the whole container is summed.
Can the check tell me which row is wrong?
No. It evaluates the column as a whole, so no single row is at fault. Pair it with a per-row rule when you need records to act on.
Can the total match while data is still wrong?
Yes. A missing row offset by a duplicated one leaves the total unchanged. Combine Sum with a row-count or uniqueness check to close that gap.
Anomaly Reporting
What kind of anomaly does the check produce?
A Shape Anomaly, one per failed evaluation. There is no Record Anomaly, because the rule evaluates an aggregate rather than individual rows.
What do the two numbers in the message mean?
The first is the total the check computed; the second is the expected total configured on the check. Their difference sizes the gap and often identifies its cause.
Why does the anomaly show no source records?
No single row is wrong, so there is nothing to list. The anomaly reports that the column's total is off.
Can I customize the anomaly message?
No. Custom Anomaly Description only replaces the message on Record Anomalies, and Sum emits a Shape Anomaly only.
Configuration
Does the Coverage slider do anything?
No. It appears because it is part of the shared check form, but the rule compares one aggregate against one value, so there is no per-row pass rate to relax.
Can I change the expected total later?
Yes. In the UI, open the check, change Sum, and click Update; see Edit a Check for the full steps. Through the API, a PUT to /api/quality-checks/{id} updates the properties object. The rule type, the target container, and the associated Check Template stay immutable.
What permission do I need to create or edit a Sum check?
The Drafter team permission on the datastore covers Draft work (creating a check as Draft or editing it while it stays Draft). Anything that puts the check into evaluation, such as creating or editing an Active check, archiving, or deleting, requires the Author team permission (or above). Viewing only requires Reporter. See Permissions for the full matrix.
Should I use Sum or Aggregation Comparison?
Use Sum when you have one exact total the column must reach. Use Aggregation Comparison when the comparison needs an operator, spans two containers, or aggregates something other than a plain sum.