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  1. Core Server
  2. SERVER-78113

not cache meaningless plan, it will increased memory overhead and increase computing overhead.

    • Type: Icon: Improvement Improvement
    • Resolution: Unresolved
    • Priority: Icon: Major - P3 Major - P3
    • None
    • Affects Version/s: None
    • Component/s: None
    • Labels:
    • Query Optimization

       when the mode is PlanCachingMode::AlwaysCache or PlanCachingMode::SometimesCache, there is a special case.
       take Classic plan cache for example:
         If the winning index's advanced = 0 && works == 1 && isEOF == true, which means we didn't get any data to rank score, all candidates 
         score is same. the score of the calculation is meaningless.

      In this case, if we cache the plan, it will increased memory overhead. when the cached plan stage pick best plan, it will trigger replan. this will increase computing overhead.

            backlog-query-optimization [DO NOT USE] Backlog - Query Optimization
            1147952115@qq.com y yz
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