apoc.merge.relationshipWithStats
Procedure

Details
Syntax	`apoc.merge.relationshipWithStats(startNode, relType, identProps, onCreateProps, endNode [, onMatchProps ]) :: (stats, rel)`
Description	Merges the given `RELATIONSHIP` values with the given dynamic types/properties. Provides queryStatistics in the result.
Input arguments	Name	Type	Description
	`startNode`	`NODE`	The start node of the relationship.
	`relType`	`STRING`	The type of the relationship.
	`identProps`	`MAP`	Properties on the relationship that are always merged.
	`onCreateProps`	`MAP`	Properties that are merged when a relationship is created.
	`endNode`	`NODE`	The end node of the relationship.
	`onMatchProps`	`MAP`	Properties that are merged when a relationship is matched. The default is: `{}`.
Return arguments	Name	Type	Description
	`stats`	`MAP`	The returned query statistics.
	`rel`	`RELATIONSHIP`	The updated relationship.

Example

Given this dataset:

CREATE (:Person {name: 'Alice'}), (:Person {name: 'Bob'})

The following query merges a KNOWS relationship between two existing nodes and returns the relationship alongside query statistics:

MATCH (a:Person {name: 'Alice'}), (b:Person {name: 'Bob'})
CALL
  apoc.merge.relationshipWithStats(
    a,
    'KNOWS',
    {id: 1},
    {since: 2019},
    b,
    {}
  )
  YIELD rel, stats
RETURN
  type(rel) AS type,
  rel.id AS id,
  rel.since AS since,
  stats.relationshipsCreated AS relationshipsCreated,
  stats.propertiesSet AS propertiesSet

Results
type	id	since	relationshipsCreated	propertiesSet
"KNOWS"	1	2019	1	2

relationshipsCreated is 1 because no matching KNOWS relationship existed. propertiesSet is 2, covering id and since. Calling the procedure again with the same identProps, the existing relationship is matched instead: relationshipsCreated becomes 0 and only the onMatchProps changes are reflected in propertiesSet.

More documentation of apoc.merge.relationshipWithStats