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  1. Core Server
  2. SERVER-63102

Make separate internalQueryPlanEvaluationWorks knobs for the classic and SBE multi-planners

    • Type: Icon: Improvement Improvement
    • Resolution: Fixed
    • Priority: Icon: Major - P3 Major - P3
    • 5.3.0, 5.2.1
    • Affects Version/s: None
    • Component/s: None
    • Fully Compatible
    • v5.2
    • QE 2022-02-21

      The classic engine and SBE have completely different implementations of multi-planning (a.k.a. runtime plan selection). In SERVER-62981, we separated the internalQueryPlanEvaluationCollFraction knob into two. That is, we introduced a new internalQueryPlanEvaluationCollFractionSbe knob which applies only to SBE and changed internalQueryPlanEvaluationCollFraction so that it applies only the classic engine. Since the two multi-planning implementations are distinct and may have different properties, it should be possible for users to tune their behavior independently.

      In the same vein, we should separate internalQueryPlanEvaluationWorks into two knobs. Again, internalQueryPlanEvaluationWorks would be just for the classic engine and internalQueryPlanEvaluationWorksSbe would apply only to SBE. That way, if the default value of 10,000 for SBE proves to be too low, users or support engineers can increase its value without disturbing the behavior of queries using the classic engine.

            david.storch@mongodb.com David Storch
            david.storch@mongodb.com David Storch
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