In Gremlin, how to query two or more vertices with same value on one property?

Question

I want to find two or more vertices which have one same property. For example, find two different Person vretices with same name. I have tried the following:

graph.traversal().V().hasLabel("Person").as("a").where("a", P.eq("a")).by("name").where("a", P.neq("a")).by("vid").toList()

but the result is null(I am quite sure that there are qualified vertices in the graph.) Any help would be greatly appreciated. Thanks.

Answer 1

You have to scan through the vertices twice. With your current traversal, you only compare each vertex with itself.

g.V().hasLabel("Person").as("a").
  V().hasLabel("Person").as("b").
  where("a", P.eq("b")).by("name").
  where("a", P.neq("b"))