$in doesn't find fields of type undef as null

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    • Minor Change
    • ALL
    • v5.0, v4.9, v4.4, v4.2
    • Query Execution 2021-06-14, Query Execution 2021-06-28
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      If you have a values which is undefined versus null - $in doesnt work

      db.a.insert({x:1,v:null})
db.a.insert({x:2,v:""})
db.a.insert({x:3})
db.a.insert({x:4,v:undefined})

db.a.find(v:null)

      Finds all except wher v is ""
      but

      db.a.find(v:{$in:[null,""]})

      fails to find the record where x = 4

      A workaround is

      db.u.find({ $or : [ {v:{$type:6}},{v:{$in:[null,""]}}]})

      Which is ugly

            Assignee:
            David Storch
            Reporter:
            John Page
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              Created:
              Updated:
              Resolved: