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  1. Core Server
  2. SERVER-13510

mongos performance issue

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    • Icon: Question Question
    • Resolution: Done
    • Icon: Major - P3 Major - P3
    • None
    • 2.4.5
    • Performance, Sharding
    • None

    Description

      data model like this:

      {gen_id: 1234, other: data}

      the data is stored on 5 shards, the gen_id is the shard key,and is not unique.

      the problem is i found that if i send exactly the SAME query many times, the first query is always slow.
      gen_id=118832718, Object Returned = 21, Time = 184.354139ms
      gen_id=118832718, Object Returned = 21, Time = 2.165057ms
      gen_id=118832718, Object Returned = 21, Time = 1.814072ms
      gen_id=118832718, Object Returned = 21, Time = 1.639094ms

      the pageFaultExceptionsThrown and accessesNotInMemory counter didn't change, so it's not likely because of page faults.
      And if i query the 5 shards directly, the numbers are close to 2-5ms.

      can anyone suggest and help me? Or dose the mongos need warm-up?

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            ramon.fernandez@mongodb.com Ramon Fernandez Marina
            dahakawang David Wang
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