Get Edges Between Vertices (Again)

[John J. Szucs]

I need to *very quickly* find the edges that directly connect two specified vertices, using either a SQL query, the Java API, or a combination of the two. If it helps, at this point in the program, I know for a fact that the two vertices are adjacent. What I'm trying to determine is how they are adjacent.

The OrientVertex.getEdges(OrientVertex, Direction, String ...) extension to the Blueprints API does what I need to do functionally, but it can be quite slow if the first vertex has many edges. Looking into the source code, I found that this is because this method essentially gets *all* of the edges from the first vertex that match the direction and label criteria and then checks if they are adjacent (connect to) the second vertex.

I have struggled with this for days. Does anyone have a better/faster approach?

Thanks!

-- John

[Luigi Dell'Aquila]

Hi John,

you have two alternatives:

1) use OrientVertex.countEdges() to check which of the two vertices has a smaller number of edges. This approach is good if you know that at most one is a supernode

2) if you know that both vertices can be supernodes, then the only efficient way to find the edge is to define and index on edge(out, in) and do the indexed query directly

I hope it helps

Thanks

Luigi

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[John J. Szucs]

Luigi,

Yes, this helps. Your option #2 is more applicable to my project.

Will OrientDB 3.0 significantly change/improve this use case? I don't want to implement this manual edge index if it will become unnecessary in (a few?) weeks.

Thanks!

-- John

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[Luigi Dell'Aquila]

Hi John,

In MATCH statement (2.2) and more in general in 3.0 we are changing the optimization of queries based on indexes, but you will still need an index on the edge for such use case, so the big part of the work will be needed anyway. 

Thanks

Luigi

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[John J. Szucs]

Luigi,

To close this out, I implemented your Option #2 suggestion. I found at very good example at http://stackoverflow.com/questions/32953396/orientdb-edge-index-via-java and the results are absolutely spectacular!

Thanks for your help!

BTW: We will soon be launching our technology, which uses OrientDB for natural language processing and Semantic Web applications, on the Web. When we do, I will definitely write up a case study for you, Luca, and the other folks at OrientDB whose help has been so essential. And when we get investment or gain some traction (users, licensees, etc.) I look forward to buying a real license, support contract, etc. because that's a win-win for all of us!

-- John

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[Luigi Dell'Aquila]

Hi John,

Happy to see it helped. Keep us posted the progress of your project!!!

Thanks

Luigi

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