Hi all,

I also thought about the vertex centrex index first, but I am afraid that the VCI can only help to filter the edges to follow, but it does not help in counting the edges. A better way to investigate is to leave out the final inV() step. So, e.g. you can count the number of distinct v2 id's with:
g.V().has('property1', 'A').outE().has('property1','E').id().map{it.get().getOutVertexId()}.dedup().count()

Note that E().id() returns RelationIdentifier() objects that contain both the edge id, the inVertexId and the OutVertexId. This should diminish the number of storage backend calls.

Best wishes,    Marc