Say I have some Cypher:
MATCH (f:FirstNode {with:$parametersF})
WITH f
MERGE (s:SomeNode {with:$parametersS})
ON CREATE SET s.source=$source
MERGE (s)-[:IS_CONNECTED_TO]->(f)
I want to be able to move the second MERGE into the ON CREATE (and change the MERGE into a CREATE) - meaning that I only want it to create the relationship if the node was just created. So something like:
...
MERGE (s:SomeNode {with:$parametersS})
ON CREATE SET s.source=$source
ON CREATE CREATE (s)-[:IS_CONNECTED_TO]->(f)
But this isn't valid cypher. Is there a better way to do this? I'm trying to reduce lock acquisition on the relationship where I know it's not needed.
In ON CREATE you can set a temporary isNew property. Then, if isNew is true, CREATE the relationship and remove isNew.
MATCH (f:FirstNode {with:$parametersF})
MERGE (s:SomeNode {with:$parametersS})
ON CREATE SET s.source=$source, s.isNew = TRUE
WITH f, s
WHERE s.isNew
CREATE (s)-[:IS_CONNECTED_TO]->(f)
REMOVE s.isNew