Question

When looking at the Tinkerpop-Blueprints API it is quite straight forward to use one type of vertices but how can I store two? E.g. Users and their interests?

And how can I get a Vertex by id? I mean, there could be a user named ‘timetabling’ as well as the interests ‘timetabling’ – how to handle that id conflict?

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I know that the first problem could be solved via introducing an index for a type-property and for the second problem I could auto generate the id and create another index for the name-property. BUT why would I then need the vertex id at all? E.g. for the in-memory there is a HashMap for all vertices which would be of no use and wasting memory! (I could solve the problem differently via combining type and name as the id but then it would inefficient if I e.g. list all users.)

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Hmmh, ok. I’m just using the vertices for the combined id (name+type) and a separate index for type. Better solutions?

Answer 1

In general it is best to rely on the automatic ID system of the underlying graph database (e.g. Neo4j, InfiniteGraph, OrientDB, etc.). The way in which you would add the information you want is as follows:

Vertex v = graph.addVertex(null)
v.setProperty("name","timetabling")

Vertex marko = graph.addVertex(null)
graph.addEdge(null, marko, v, "hasInterest")
Verte aType = graph.addVertex(null)
graph.addEdge(null, aType, v, "hasType")

In short, the ID of a vertex/edge is a non-domain-specific way of retrieving vertices/edges. Generally, it is best to use properties in your domain model for indexing.

Hope that speaks to your question,
Marko.

http://markorodriguez.com