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  1. Core Server
  2. SERVER-15152

When evaluating plans, some index candidates cause complete index scan

    • Type: Icon: Bug Bug
    • Resolution: Done
    • Priority: Icon: Major - P3 Major - P3
    • 2.6.5, 2.7.7
    • Affects Version/s: 2.6.4
    • Component/s: Querying
    • Labels:
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    • ALL

      When running query during multiPlanRunner stage some combinations of values and data distribute can cause a fast query have a possible plan/index choice where full index scan (of a non-selective attribute) would be evaluated. Running explain(true) can show which index has unusually high nscanned.

      It seems during race-off the full scan is finished, causing some percentage of queries to be excessively slow.

            Assignee:
            david.storch@mongodb.com David Storch
            Reporter:
            asya.kamsky@mongodb.com Asya Kamsky
            Votes:
            2 Vote for this issue
            Watchers:
            13 Start watching this issue

              Created:
              Updated:
              Resolved: