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.
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SERVER-14525 Perf regression in 2.6.2 caused by not caching plans that tie during plan ranking
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- Closed
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- Closed
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- related to
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- Closed
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