[jira] [Commented] (FLINK-3806) Revert use of DataSet.count() in Gelly

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-3806?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15310162#comment-15310162 ] 

ASF GitHub Bot commented on FLINK-3806:
---------------------------------------

Github user vasia commented on the pull request:

    https://github.com/apache/flink/pull/2036
  
    Thanks @greghogan! It looks like you have some checkstyle violation, otherwise +1.


> Revert use of DataSet.count() in Gelly
> --------------------------------------
>
>                 Key: FLINK-3806
>                 URL: https://issues.apache.org/jira/browse/FLINK-3806
>             Project: Flink
>          Issue Type: Improvement
>          Components: Gelly
>    Affects Versions: 1.1.0
>            Reporter: Greg Hogan
>            Assignee: Greg Hogan
>            Priority: Critical
>             Fix For: 1.1.0
>
>
> FLINK-1632 replaced {{GraphUtils.count}} with {{DataSetUtils.count}}. The former returns a {{DataSet}} while the latter executes a job to return a Java value.
> {{DataSetUtils.count}} is called from {{Graph.numberOfVertices}} and {{Graph.numberOfEdges}} which are called from {{GatherSumApplyIteration}} and {{ScatterGatherIteration}} as well as the {{PageRank}} algorithms when the user does not pass the number of vertices as a parameter.
> As noted in FLINK-1632, this does make the code simpler but if my understanding is correct will materialize the Graph twice. The Graph will need to be reread from input, regenerated, or recomputed by preceding algorithms.



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