[jira] [Commented] (SPARK-3650) Triangle Count handles reverse edges incorrectly

["Robin East (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-3650?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14603016#comment-14603016 ] 

Robin East commented on SPARK-3650:
-----------------------------------

What is the status of this issue? A user on the mailing list just ran into to this issue. It looks like PR-2495 should fix the issue. Is there a version that is being targeted for the fix?

> Triangle Count handles reverse edges incorrectly
> ------------------------------------------------
>
>                 Key: SPARK-3650
>                 URL: https://issues.apache.org/jira/browse/SPARK-3650
>             Project: Spark
>          Issue Type: Bug
>          Components: GraphX
>    Affects Versions: 1.1.0, 1.2.0
>            Reporter: Joseph E. Gonzalez
>            Priority: Critical
>
> The triangle count implementation assumes that edges are aligned in a canonical direction.  As stated in the documentation:
> bq. Note that the input graph should have its edges in canonical direction (i.e. the `sourceId` less than `destId`)
> However the TriangleCount algorithm does not verify that this condition holds and indeed even the unit tests exploits this functionality:
> {code:scala}
> val triangles = Array(0L -> 1L, 1L -> 2L, 2L -> 0L) ++
>         Array(0L -> -1L, -1L -> -2L, -2L -> 0L)
>       val rawEdges = sc.parallelize(triangles, 2)
>       val graph = Graph.fromEdgeTuples(rawEdges, true).cache()
>       val triangleCount = graph.triangleCount()
>       val verts = triangleCount.vertices
>       verts.collect().foreach { case (vid, count) =>
>         if (vid == 0) {
>           assert(count === 4)  // <-- Should be 2
>         } else {
>           assert(count === 2) // <-- Should be 1
>         }
>       }
> {code}



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