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  1. Core Server
  2. SERVER-47597

executionTimeMillisEstimate seems incorrect for some stages

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    • Icon: Bug Bug
    • Resolution: Gone away
    • Icon: Major - P3 Major - P3
    • None
    • 4.4.0-rc1
    • Aggregation Framework
    • None
    • ALL

    Description

      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...

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            asya.kamsky@mongodb.com Asya Kamsky
            asya.kamsky@mongodb.com Asya Kamsky
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              Created:
              Updated:
              Resolved: