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  1. Core Server
  2. SERVER-77510

Reduce Bonsai sampling variability in perf variants

    • Type: Icon: Task Task
    • Resolution: Fixed
    • Priority: Icon: Major - P3 Major - P3
    • 7.1.0-rc0
    • Affects Version/s: None
    • Component/s: None
    • Query Optimization
    • Fully Compatible
    • QO 2023-06-12, QO 2023-06-26

      As a result of investigation work, it looks like sampling CE generates variable plans.

      Svilen's suggestion on the scope was to make sampling to read only from the beginning of the collection, rather than getting a true $sample (on the performance variants). We could hide this behaviour behind an internal test-only query knob in order to increase testing stability.

      If this still does not eliminate the variability, we can consider disabling the most variable workloads, or disabling the sampling variants entirely.

        1. Heuristic, Micro, ops_per_sec.png
          86 kB
          Alya Berciu
        2. Sampling, Micro, ops_per_sec noisy.png
          102 kB
          Alya Berciu
        3. Screenshot 2023-06-21 at 15.17.49.png
          317 kB
          Alya Berciu
        4. Screenshot 2023-06-21 at 15.19.29.png
          225 kB
          Alya Berciu
        5. Top CoV for ops_per_sec, thread_level 1.png
          101 kB
          Alya Berciu

            Assignee:
            alya.berciu@mongodb.com Alya Berciu
            Reporter:
            alya.berciu@mongodb.com Alya Berciu
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              Created:
              Updated:
              Resolved: