Unique index on superclass and value reused between different subclasses

Question

In a project using Spring Data Neo4j 3.2, I have a model which looks like:

@NodeEntity
public abstract class A {
    @GraphId
    public Long id;
    @Indexed(unique = true)
    public Long technicalId;
}

@NodeEntity
public class B extends A {}

@NodeEntity
public class C extends A {}

I missed the paragraph in the documentation talking about the default merge feature, and we ran into the following situation without getting an exception:

B b = new B();
b.technicalId = 42;
neo4jTemplate.save(b);
// I now have Node[1] in Neo4j with the following labels: B, _B, A

C c = new C();
c.technicalId = 42;
neo4jTemplate.save(c);
// No exception and Node[1] now has the following labels: B, _B, A, C, _C

So OK, the situation can be avoided by:

either using instance-based indices:

@NodeEntity
public abstract class A {
    @GraphId
    public Long id;
    @Indexed(unique = true, level = Level.INSTANCE)
    public Long technicalId;
}

or using failOnDuplicate (though it's not mentioned in the documentation, even for 3.3, but I found it here and here) which avoids creating 3 indices instead of 1, so less I/Os on writes and less disk space used:
```
@NodeEntity
public abstract class A {
    @GraphId
    public Long id;
    @Indexed(unique = true, failOnDuplicate = true)
    public Long technicalId;
}
```

However, isn't it a bug that the default behavior will change the nature of the node (when there's a class hierarchy involved) and create a mix of labels which could prevent the instantiation of an entity? I mean the node now has 2 underscore-prefixed labels: n:B:_B:A:C:_C, because the 2 Cypher queries that were executed were:

MERGE (n:`A` {`technicalId`: {value}})
  ON CREATE SET n={props} SET n:SupplierCompany
  return n
// params {value=42, props={technicalId=42}}
match (n)
  where id(n)={nodeId}
  set n:`A`:`C`:`_C`
// params {nodeId=1}

Should I raise an issue with a test case on the SDN JIRA or github?

Unique index on superclass and value reused between different subclasses

0 Answers0