[jira] [Created] (TINKERPOP-1741) GroupStep's on-the-fly reducer is a bit screwy

["Daniel Kuppitz (JIRA)" <ji...@apache.org>]

Daniel Kuppitz created TINKERPOP-1741:
-----------------------------------------

             Summary: GroupStep's on-the-fly reducer is a bit screwy 
                 Key: TINKERPOP-1741
                 URL: https://issues.apache.org/jira/browse/TINKERPOP-1741
             Project: TinkerPop
          Issue Type: Bug
          Components: process
    Affects Versions: 3.2.5
            Reporter: Daniel Kuppitz
            Assignee: Marko A. Rodriguez


Without {{dedup():}}

{noformat}
gremlin> g.V().both().has("age").group("a").by("age").by(values("name").fold()).barrier().select("a").limit(1)
==>[32:[josh,josh,josh],35:[peter],27:[vadas],29:[marko,marko,marko]]
{noformat}

With {{dedup()}}:

{noformat}
gremlin> g.V().both().has("age").group("a").by("age").by(values("name").dedup().fold()).barrier().select("a").limit(1)
==>[32:[josh:josh],35:[peter:peter],27:[vadas:vadas],29:[marko:marko]]
{noformat}

Why do the values end up being maps? That's pretty unexpected.

As a workaround we can do this:

{noformat}
gremlin> g.withSideEffect("a", [:].withDefault {[] as Set}).V().both().has("age").group("a").by("age").by(values("name").fold()).barrier().select("a").limit(1)
==>[27:[vadas],32:[josh],29:[marko],35:[peter]]
{noformat}

Also note, that {{cap()}} behaves correctly, even though we're using {{dedup()}}:

{noformat}
gremlin> g.V().both().has("age").group("a").by("age").by(values("name").dedup().fold()).barrier().cap("a")
==>[32:[josh],35:[peter],27:[vadas],29:[marko]]
{noformat}



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