Max Length Anomaly Reporting
How the Max Length check reports violations: the anomaly messages it produces, what the numbers mean, how the offending value appears in Source Records, and how to replace the default message with a value from your own data.
Anomaly Messages
On a scalar String field at 100% coverage, Max Length reports violating rows as Record Anomalies. Below 100% coverage, a failed coverage assertion produces one Shape Anomaly for the dataset. On an array field, in either mode, the rule runs as a field-level check and always reports a Shape Anomaly. The two templates are:
Record Anomaly
The field '<field_name>' has value '<row_value>' (length <measured>), which exceeds the maximum length of <length>
Shape Anomaly
When a filter is set, both Record and Shape Anomaly messages end with [filter: <expression>].
Scan settings can group a large number of Record Anomalies into one rolled-up Shape Anomaly. This behavior applies across rule types and is documented under Maximum Record Anomalies per Check.
What the Numbers Mean
- X.XXX%: the fraction of filtered rows that fail the length rule.
- N: the total number of rows the check evaluated (after the filter, if any). Rows with NULL values count in this total because they pass.
- K: the number of rows that fail the length rule. The Record Anomaly also echoes the measured length of the offending value, so you can see how far it is from the limit without querying the data.
Source Records Behavior
The offending cell is highlighted with an orange outline and an orange-tinted background in the Source Records view, mirroring the platform's standard violation rendering. Only the cell carrying the failing value is highlighted; the rest of the row renders normally.
Custom Anomaly Description
Max Length supports Custom Anomaly Description because it emits Record Anomalies. When anomaly_message_field (or the Custom Anomaly Description toggle in the UI) is set to another column on the same row, the Record Anomaly message becomes the value of that column for the violating row. When the referenced column is null, missing, or empty, the standard template is used instead.
Because the option only applies to Record Anomalies, it does not affect Shape Anomalies, which always use the fixed template.
See Also
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How It Works
The complete reference: definition, field scope, the length property, NULL handling, arrays, filter behavior, and coverage.
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Examples
Three production scenarios with sample data, anomaly messages, and the SQL equivalent of what the check evaluates.
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Best Practices
Guidelines for choosing the length, pairing rules, and keeping the signal clean.
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Permissions
The team permission each action needs: view, create, edit, archive, restore, and delete.