Less Than Field Check FAQ

Answers to common questions about how the Less Than Field check compares two fields on the same row, how NULLs and tolerance behave, and how anomalies are reported, grouped by topic.

Behavior

Are equal values accepted?

It depends on the Inclusive setting: on, an equal pair passes; off, it is flagged.

What happens when one of the two fields is NULL?

With no comparator configured, the row passes: with nothing to compare, the check does not report a violation, and a column that is entirely NULL never fails this rule. With a Numeric or Datetime comparator configured, only a row where both values are NULL passes; a row with exactly one NULL is reported as a violation. Either way, pair the check with Not Null when presence is part of the rule.

Can I compare fields of different types?

No. The target field must be a Date, Timestamp, Integral, or Fractional field, and the compared field must carry the same type as the target; the platform rejects the check when the two types differ. Normalize one side upstream, or with a Computed Field, so both columns carry the same type.

What do the comparators do?

They give the comparison a margin. Numeric accepts an absolute amount or a percentage; Datetime accepts a duration. Leave them empty when the relationship must be exact.

Does the filter run before or after the comparison?

Before. The platform applies the filter first and then evaluates only the rows that pass the filter. Filtered-out rows cannot trigger an anomaly and are not counted in the totals.

Anomaly Reporting

What do the anomaly messages look like?

Record Anomaly: The field '<field_name>' has value <row_value>, which is not less than the value of '<compared_field>'

Shape Anomaly: For the field '<field_name>', X.XXX% of N records (K) are not less than '<compared_field>'

When a filter is set, both messages end with [filter: <expression>].

Does Less Than Field produce Record Anomalies, Shape Anomalies, or both?

At 100% coverage (the default), violating rows are reported as Record Anomalies. Below 100% coverage, a failed coverage assertion produces one Shape Anomaly for the dataset. A scan can also roll up a large number of Record Anomalies into one Shape Anomaly.

Which cell is highlighted in Source Records?

The target field's cell. The compared field renders normally, so open both columns side by side to see why the row failed.

Does Custom Anomaly Description work for Less Than Field?

Yes. Less Than Field emits Record Anomalies, so the anomaly_message_field payload field (and the Custom Anomaly Description toggle in the UI) replaces the Record Anomaly message with the value of the named column on the violating row. When that column is null, missing, or empty, the standard Record template is used instead. The Shape Anomaly always uses the fixed template.

Configuration

Can I lower the coverage on Less Than Field check?

Yes. Coverage at 1.0 (100%) means every row must pass. Lowering coverage to 0.995 allows up to 0.5% of rows to fail without raising an anomaly; once the failing fraction goes past that, the check reports a Shape Anomaly. Use lower coverage with care: a real regression that happens to fall just under the threshold will not raise an alert at all.

Can I change the compared field on an existing check?

Yes. In the UI, open the check, change Field to compare, and click Update; see Edit a Check for the full steps. Through the API, a PUT to /api/quality-checks/{id} updates properties.field_name. The rule type, the target container, and the associated Check Template stay immutable; see the API page for the editable/immutable matrix.

What permission do I need to create or edit Less Than Field 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.

When should I use Less Than instead?

Use Less Than when the boundary is a constant rather than another column. Less Than Field exists for relationships between two values on the same row, which keep holding as the data changes.