Call APOC procedure in apoc.periodic.iterate - neo4j

Question

I am trying to add new relationships based on a property of existing relationships with the apoc.create.relationship function:
:auto CALL apoc.periodic.iterate(
"MATCH (source:Entity)-[r:TEMP_RELATION]->(target:Entity) RETURN source, r, target",
"CALL apoc.create.relationship(source, r.`Interaction-type`, r, target) YIELD rel RETURN rel",
{batchSize:5}
);
When I run this query I get Java heap errors (max heap is 8g). It looks like iterate is not actually iterating but loading too much into memory. I use Neo4j 4.4.8 on a Mac (M1).
Any ideas why there is a memory leak here?

Answer 1

Since neo4j 4 the behavior changed, when you pass a node or relationship to a separate transaction/statement it carries along it's own transaction where it originated from.
So all updates are accumulated on that original transaction.
To avoid that you have to "rebind" the nodes and rels best by returning id(n) as id or id(r) as relId
Then you can re-match the node and rels in the update statement: WHERE id(n) = id and use it from there.
In your example:
:auto CALL apoc.periodic.iterate(
"MATCH (source:Entity)-[r:TEMP_RELATION]->(target:Entity) RETURN id(source) as sId, properties(r) as props, r.`Interaction-type` as type, id(target) as tId",
"MATCH (source), (target) where id(source) = sId AND id(target) = tId
CALL apoc.create.relationship(source, type, props, target) YIELD rel RETURN count(*)",
{batchSize:10000}
);