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Not Null Troubleshooting

Common problems when creating and running a Not Null check, their causes, and how to resolve them.

Validation Fails When Creating the Check

Clicking Validate returns an error instead of a success message.

Cause: The rule could not run against the selected data. The most common reasons are an invalid Filter Clause expression, a connection problem with the source, or a container that failed to load.

Resolution:

  1. Review the error message: it explains what needs attention.
  2. Check the Filter Clause for typos: it must be a valid SQL WHERE expression for the selected container.
  3. If the message says the container is marked as Unloadable, the container was skipped after repeated operation failures. Follow the steps in Unloadable Container Error.

Rows With Empty Strings Are Not Flagged

Rows that look empty in the selected field pass the check.

Cause: The rule tests for NULL, not for emptiness. An empty string, a space, or a placeholder such as n/a is a present value.

Resolution: Normalize blanks to NULL upstream, or expose a Computed Field that maps them to NULL and point the check at it. To also reject blanks in place, pair with Matches Pattern.

A Multi-Field Check Reports Too Much

The check fires on rows where only one of several columns is empty.

Cause: With several fields selected, the rule asserts all of them together: a row fails as soon as one is empty.

Resolution: That is the intended behavior for mandatory columns. When the rule is really "at least one of these", use Any Not Null instead. When each column needs its own triage path, split the check into one per field.

An Array Row With NULL Elements Passes

A row whose array contains empty elements is accepted.

Cause: By default the array is tested as a whole: a non-NULL array passes even when its elements are NULL.

Resolution: Turn on Array Element Context so every element must be populated.

An Edited Check Keeps Behaving the Old Way

You changed the configuration but the anomaly list did not change.

Cause: Edits take effect on the next Scan. Saving the check does not re-evaluate the data, and anomalies raised under the previous configuration are not modified.

Resolution: Run a Scan on the container (or wait for the scheduled one). Old anomalies stay open until you triage them or a Full scan with Auto Resolve clears them. See What Happens to Existing Anomalies.

No Anomalies Although the Data Looks Wrong

A Scan ran, the data clearly breaks the rule, but nothing was reported.

Cause: One of these configurations is excluding the violations:

  • The check is in Draft status: Draft checks are not evaluated by Scans.
  • The Filter Clause excludes those rows before the evaluation runs.
  • Coverage is below 100% and the failing fraction stayed within the tolerance, so the check passed.

Resolution: Confirm the check is Active and test the filter expression against the offending rows. Then review the coverage setting; see Coverage and Tolerance.

Expected One Anomaly per Row, Got a Single Rolled-Up One

Many rows failed, but the scan reported one Shape Anomaly instead of per-row Record Anomalies.

Cause: When the number of failing rows exceeds the scan's rollup threshold, the per-row findings are grouped into one rolled-up Shape Anomaly.

Resolution: This is expected behavior; the rolled-up anomaly carries sampled source records. To change the threshold, see Maximum Record Anomalies per Check.