[Feature Request] Ignore some labels in native projections

[Cobra5197]

Is your feature request related to a problem? Please describe. Neo4j allows nodes to have multiple labels. My problem is that I wanted to remove nodes from the projection that had a particular label in addition to another label. Example: I have Entity nodes but some are super nodes which I would like to remove from the projection, so I wrote a cypher query to find and set a label to these nodes.

Describe the solution you would like I would like to have for the native projection another configuration parameter which follow the same logic as nodeProjection parameter to ignore nodes that have certain labels.

Describe alternatives you have considered I am using Cypher projection but that is not optimized like native projection: MATCH (n:Entity) WHERE NOT n:Super RETURN id(n) AS id, labels(n) AS labels

Additional context Also, if this feature is developed, in write mode, the ignored nodes property should be set to null. For example, if in write mode I choose the _group as the property name as the result for the algorithm, the ignoreNodes should not have this property because they may have been in the projection before.

Regards, Cobra

[vnickolov]

@Cobra5197 thank you for raising this, we are going to look at it. In the meantime if this is blocking you, maybe you can invert the labels, what I mean is with the Cypher query that you use to set node label to Super you can probably set label NotSuper (or something that makes more sense in your domain) on the "normal" nodes and use that label for projection instead.

I hope this helps.

[Cobra5197]

Thank you, it's a good idea :)

[Mats-SX]

Hello @Cobra5197

We have thought a bit about this feature and we have decided that we will not add it. Behind this decision are a few observations:

• native projections are intentionally limited in their expressivity in order to be simple to understand, use, and optimise
• Cypher projections already offer the increased expressivity (which you also note in your great issue description)
• we are working to improve Cypher projections -- for example, the new Cypher Aggregation alternative that was added in a recent version, but also to make them faster. We prefer to focus our efforts in this direction.
• it is possible to work around the limitation by doing what @vnickolov recommends above
• adding support for this nuanced way of label predicate would satisfy this exact use case, but other predicates such as X AND Y AND NOT Z or X OR Y OR A AND B (where X, Y, Z, A, B are labels) would not be covered. Cypher projections do cover all such predicates.

I hope this is an acceptable answer.

All the best Mats