executionTimeMillisEstimate seems incorrect for some stages

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    • Type: Bug
    • Resolution: Gone away
    • Priority: Major - P3
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    • Affects Version/s: 4.4.0-rc1
    • Component/s: Aggregation Framework
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    • ALL
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    • 3
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      In SERVER-21784 we added to each stage more details in explain output.

      However, after first stage, every stage seems to show exact same value which is the total time execution of the entire pipeline which seems like a bug.

                    {  "$cursor": {
                             ...
                              },
                              "nReturned" : NumberLong(500000),
                              "executionTimeMillisEstimate" : NumberLong(269)
                      },
                      {
                              "$lookup" : {
                                      ...
                              },
                              "nReturned" : NumberLong(500000),
                              "executionTimeMillisEstimate" : NumberLong(16337)
                      },
                      {
                              "$group" : {
                                    ...
                              },
                              "nReturned" : NumberLong(4000),
                              "executionTimeMillisEstimate" : NumberLong(16337)
                      },
                      {
                              "$group" : {
                                   ...
                              },
                              "nReturned" : NumberLong(1),
                              "executionTimeMillisEstimate" : NumberLong(16337)
                      },
                      {
                              "$project" : {
                                     ...
                              },
                              "nReturned" : NumberLong(1),
                              "executionTimeMillisEstimate" : NumberLong(16337)
                      }
              ],
      

      FYI the explain actually took 16339 ms to run...

            Assignee:
            Asya Kamsky
            Reporter:
            Asya Kamsky
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              Created:
              Updated:
              Resolved: