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  1. Core Server
  2. SERVER-79400

Implement number of documents tie breaking heuristics

    • Fully Compatible
    • v7.0, v6.0, v5.0
    • QO 2023-08-07, QO 2023-08-21, QO 2023-09-04
    • 161

      In case if several candidate plans achieved the same highest score, prefer a plan which fetches a smaller number of documents.

      Implementation details:
      In pickBestPlan function, right after we sort candidate plans:
      1. Identified the tied plans
      2. Compare the tied plans by number of examined documents
      3. Increase score for the plan with fewer examined documents by epsilon value (which is defined above as a constant equals to 1e-4)
      4. re-sort the plans

            Assignee:
            katie.yang@mongodb.com Katie Yang (Inactive)
            Reporter:
            alexander.ignatyev@mongodb.com Alexander Ignatyev
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              Created:
              Updated:
              Resolved: