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https://issues.apache.org/jira/browse/FLINK-2905?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14980871#comment-14980871
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Vasia Kalavri commented on FLINK-2905:
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Hey [~mju],
thanks! I took a quick look at your code and here are my comments:
- For (1) and (2), I think you can avoid one join. Get the vertex ids from the
intersected edges (with a flatmap-distinct) and then join with the
union-distinct of the input graphs to get the vertex values. We can also
optimize for the case when vertices don't have associated values; then, the
whole second step can be omitted and we can simply compute the result from the
edges intersection.
- I'm not really sure I see the point of {{intersectOnVertices}}. When would
you use it instead of the other two? Also, it looks like really expensive to
compute.
> Add intersect method to Graph class
> -----------------------------------
>
> Key: FLINK-2905
> URL: https://issues.apache.org/jira/browse/FLINK-2905
> Project: Flink
> Issue Type: New Feature
> Components: Gelly
> Affects Versions: 0.10
> Reporter: Martin Junghanns
> Assignee: Martin Junghanns
> Priority: Minor
>
> Currently, the Gelly Graph supports the set operations
> {{Graph.union(otherGraph)}} and {{Graph.difference(otherGraph)}}. It would be
> nice to have a {{Graph.intersect(otherGraph)}} method, where the resulting
> graph contains all vertices and edges contained in both input graphs.
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