Duplicate Detection Rules - Blank Value

Dataverse has a duplicate detection capability which if configured can warn users about duplicate records.

Part of the configuration requires duplicate detection rules which specify which columns must match in order for a record to be considered a duplicate.

Consider two contact records with no value for Email as per the table.

First Name	Email
Fred
Fred

And assume we have a duplicate rule based on exact match of Email only with Ignore Blank Values selected.

This means ignore records where there is no value for Email. So the two records in the table (without a value for Email) would not be flagged as duplicates.

Conversely, if Ignore Blank Values is not selected as per the screenshot below, you might expect the two records in the table to be considered duplicates.

Screenshot of Duplicate Detection Rule with match on Email column only

But, if there is only one column configured in the rule, blank values are ignored and the two records in this example would not be flagged as duplicates.

Screeshot of Duplicate Detection Rule with match on Email and First Name columns

If there are two or more columns in the rule, then the Ignore Blank Values setting is considered and the two records in this example would be flagged as duplicates.