Distinct Count Anomaly Reporting
How the Distinct Count check reports a cardinality mismatch: the message it produces, what the numbers mean, and why there is nothing to report per row.
Anomaly Messages
Distinct Count emits Shape Anomalies only: one anomaly per failed evaluation, never per row. The template is:
Shape Anomaly
When a filter is set, the Shape Anomaly message names it at the end of its first sentence, as (applied to records where <expression>).
What the Numbers Mean
<observed>: the approximate distinct count the scan measured on the filtered rows.<expected>: the expected number configured on the check.<comparison>: the configured operator, written out in full, such asequal toorgreater than or equal to.
Source Records Behavior
Distinct Count measures the dataset as a whole rather than individual rows, so the anomaly carries no per-row source records. To find the values behind the number, group the column and count.
Custom Anomaly Description
Custom Anomaly Description does not apply to this rule. The option replaces the message on Record Anomalies, and Distinct Count emits a Shape Anomaly only.
See Also
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How It Works
The complete reference: definition, field scope, the comparison operators, approximation, NULL handling, filter behavior, and why coverage does not apply.
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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 operator, allowing for approximation, and keeping the signal clean.
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Permissions
The team permission each action needs: view, create, edit, archive, restore, and delete.