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

["Greg Hogan (JIRA)" <ji...@apache.org>]

Greg Hogan created FLINK-3806:
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             Summary: 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
            Priority: Critical


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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