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我有一个 DocumentDB，其中有一些非常慢的查询和 CPU 峰值。基于分析器的最慢查询之一，如下所示。我试图了解什么样的问题会导致这个查询变得慢得吓人：

{
  "op":"update",
  "ts":1597203362481,
  "ns":"db.registrations",
  "command":{
    "q":{
      "_id":"5ca3f02edb3fb733eb2f0f46"
    },
    "u":{
      "$set":{
        "last_active_at":"2020-08-12T03:33:43.278Z",
        "updated_at":"2020-08-12T03:33:43.278Z"
      }
    }
  },
  "nMatched":1,
  "nModified":1,
  "protocol":"op_query",
  "millis":139201,
  "planSummary":"IXSCAN",
  "execStats":{
    "stage":"UPDATE",
    "nReturned":"0",
    "executionTimeMillisEstimate":"138855.197",
    "inputStages":[
      {
        "stage":"LIMIT_SKIP",
        "nReturned":"1",
        "executionTimeMillisEstimate":"138822.167",
        "inputStage":{
          "stage":"IXSCAN",
          "nReturned":"1",
          "executionTimeMillisEstimate":"0.305",
          "indexName":"_id_",
          "direction":"forward"
        }
      },
      {
        "stage":"IXSCAN",
        "nReturned":"1",
        "executionTimeMillisEstimate":"138841.412",
        "indexName":"_id_",
        "direction":"forward"
      }
    ]
  },
  "client":"10.70.13.125:42436",
  "user":"db"
}

这些字段都没有：last_active_at也updated_at没有索引。那么为什么这会这么慢呢？

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0 回答 0