Merge Overlapping Groups

Merge Overlapping Groups

Merge Overlapping Groups is a match setting that controls how MatchLogic forms groups of related records. It determines whether indirect relationships are used to cluster records together.

Match settings panel showing the Merge Overlapping Groups toggle switch in the enabled position

What Is Transitive Closure

When Merge Overlapping Groups is enabled (the default), MatchLogic applies transitive closure to group formation. This means:

  • If Record A matches Record B
  • And Record B matches Record C
  • Then A, B, and C are all placed in the same group — even if A and C do not directly match each other

The relationship flows through intermediate records. If B is the link between A and C, all three are considered part of the same duplicate cluster.

When Disabled

When Merge Overlapping Groups is disabled, only directly matched pairs are grouped together. Using the same example:

  • Record A matches Record B — they form a pair
  • Record B matches Record C — they form a separate pair
  • A and C are not grouped together because they do not directly match

This results in smaller, more precise groups but may split what is logically a single entity across multiple groups.

When to Enable (Default)

Keep Merge Overlapping Groups enabled when:

  • Deduplicating records — you want to find complete clusters of duplicates so you can pick the best record from each cluster
  • Data has variant spellings — Record A might match B (similar first name), B might match C (similar last name), and together they represent the same person
  • You want comprehensive grouping — no potential duplicate should be left out of its cluster

When to Disable

Disable Merge Overlapping Groups when:

  • You need pair-level precision — you want to review each matched pair independently without transitive grouping
  • Chaining risk is high — in large datasets, transitive closure can create very large groups where distantly related records are clustered together. Disabling prevents this "chaining" effect.
  • You want conservative results — only records that directly match should be grouped

Important

Disabling this setting can significantly change your match results. A dataset that produces 100 groups with merging enabled might produce 300 smaller groups with it disabled. Review your results carefully after changing this setting.

Tip

If you see unexpectedly large groups in your match results (50+ records in a single group), it may be caused by transitive closure chaining. Try disabling Merge Overlapping Groups or tightening your match strictness to reduce false transitive links.

Finding This Setting

The Merge Overlapping Groups toggle is located in the match settings area of the Match Definitions page. Adjust it before running your match. Changing it after a match has been run requires re-running the match to see the effect.