No support for Multi-label nodes

[lvca]

Discussed in #362

^{Originally posted by datanostra April 8, 2022}
Hi,

I'm working on a graph db benchmark and I have a specific use case that might often occurred which is : create an edge without knowing the type of the source or the target nodes.

I can make it works using inheritance in SQL, creating a Node type, which is extended by all my types :

Create types :
CREATE VERTEX TYPE Node;
CREATE VERTEX TYPE Transaction EXTENDS Node;
CREATE VERTEX TYPE City EXTENDS Node;

Create Nodes :
INSERT INTO Transaction set id = "A"
INSERT INTO City set id = "B"

Then I can query my ingested objects without knowing if they are of types Transaction or City :

• SELECT FROM Node WHERE id = 'id_source'
• CREATE EDGE Relation_Type FROM (SELECT FROM Node WHERE id = 'A') TO (SELECT FROM Node WHERE id = 'B') IF NOT EXISTS

Nevertheless, I would like to be able to create the same mechanism with Cypher.

The problems are :

• the inheritance does not seem replicated to the graph model and then not accessible via Cypher.

• multi-label mechanism does not seem available in ArcadDB. For example, this CYPHER query is not working : CREATE (n:Transaction:Node {id: 'some_id'})

• Unlabeled Cypher queries does not seem to be scalable (MATCH (n) WHERE n.id = "some_id" RETURN n). One reason of this is that we can't benefit from indexes to get optimized access to nodes.