[jira] [Closed] (TINKERPOP-1009) Add a CAUTION to documentation about HadoopGraph and getting back elements

["Marko A. Rodriguez (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/TINKERPOP-1009?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Marko A. Rodriguez closed TINKERPOP-1009.
-----------------------------------------
    Resolution: Fixed

> Add a CAUTION to documentation about HadoopGraph and getting back elements
> --------------------------------------------------------------------------
>
>                 Key: TINKERPOP-1009
>                 URL: https://issues.apache.org/jira/browse/TINKERPOP-1009
>             Project: TinkerPop
>          Issue Type: Improvement
>          Components: documentation, hadoop
>    Affects Versions: 3.1.0-incubating
>            Reporter: Marko A. Rodriguez
>            Assignee: Marko A. Rodriguez
>             Fix For: 3.1.1-incubating
>
>
> This works, but its crazy to do for large data over non-random access sources.
> {code}
> // g is a SparkGraphComputer traversal
> gremlin> g.V().out().out()
> ==>v[3]
> ==>v[5]
> gremlin>
> {code}
> Why is this crazy? Cause for each vertex, there is a {{graph.vertices(id)}} lookup which, for HadoopGraph is a linear scan of the input format. This is nutz for massive graphs.
> {code}
> gremlin> g.V().out().out().toList().get(0).getClass()
> ==>class org.apache.tinkerpop.gremlin.hadoop.structure.HadoopVertex
> {code}
> In our docs, we should state that you should use HadoopGraph to generate reductions and not just swathes of vertices. Or, if you need a vertex, don't get the vertex, get ONLY its ID.
> {code}
> gremlin>  g.V().out().out().id()
> ==>3
> ==>5
> {code}
> Finally, note that in {{TraversalVertexProgram}} we have a configuration that we never exposed to the user but we should via {{gremlin.traversalVertexProgram.attachElements}}.
> https://github.com/apache/incubator-tinkerpop/blob/master/gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/computer/traversal/step/map/ComputerResultStep.java#L56
> https://github.com/apache/incubator-tinkerpop/blob/master/gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/computer/traversal/step/map/ComputerResultStep.java#L87-L90
> As we have it now {{attachElements}} is always {{TRUE}}.



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