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  1. Core Server
  2. SERVER-27644

distinct on a view doesn't "flatten" array members

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Details

    • Fully Compatible
    • ALL
    • v3.4
    • Query 2017-02-13

    Description

      If you create an identity view on a collection which has some field that contains an array, the result of db.collection.distinct("thatfield") and db.identityview.distinct("thatfield") will not be the same.

      db.coll.find()
      		 
      { "_id" : ObjectId("5876aaed34e6e16cd498d61c"), "a" : 1 }
      		 
      { "_id" : ObjectId("5876aaf034e6e16cd498d61d"), "a" : [ 2 ] }
      		 
      { "_id" : ObjectId("5876aaf734e6e16cd498d61e"), "a" : [ 3, 4 ] }
      		 
      db.coll.distinct("a")
      		 
      [ 1, 2, 3, 4 ]
      		 
      db.createView("view","coll",[])
      		 
      { "ok" : 1 }
      		 
      agg@127.0.0.1:27017(3.4.1) > db.view.distinct("a")
      		 
      [ [ 3, 4 ], [ 2 ], 1 ]

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          is related to

          Bug - A problem which impairs or prevents the functions of the product. SERVER-55112 Behaviour of distinct differs between collections and views

          • Major - P3 - Major loss of function.
          • Closed
          related to

          Improvement - An improvement or enhancement to an existing feature or task. SERVER-27484 allow $setUnion in $group

          • Minor - P4 - Minor loss of function, or other problem where easy workaround is present.
          • Closed

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            People

              kyle.suarez@mongodb.com Kyle Suarez
              asya.kamsky@mongodb.com Asya Kamsky
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                Updated:
                Resolved: