Uploaded image for project: 'Core Server'
  1. Core Server
  2. SERVER-15152

When evaluating plans, some index candidates cause complete index scan

    XMLWordPrintable

    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major - P3
    • Resolution: Fixed
    • Affects Version/s: 2.6.4
    • Fix Version/s: 2.6.5, 2.7.7
    • Component/s: Querying
    • Labels:
      None
    • Operating System:
      ALL
    • Backport Completed:
    • Case:

      Description

      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.

        Attachments

          Issue Links

            Activity

              People

              • Votes:
                2 Vote for this issue
                Watchers:
                14 Start watching this issue

                Dates

                • Created:
                  Updated:
                  Resolved: