Migrate Data into a Time Series Collection将数据迁移到时间序列集合

(Optional) Transform your data to create a metadata field if one doesn't exist. This field is not required.（可选）如果不存在元数据字段，则转换数据以创建元数据字段。此字段不是必需字段。

If the original collection doesn't have a metadata field, use the $addFields aggregation stage to add it.如果原始集合没有元数据字段，请使用$addFields聚合阶段进行添加。

Consider a collection with weather data that uses the format:考虑使用以下格式集合天气数据：

 {
    "_id" : ObjectId("5553a998e4b02cf7151190b8"),
    "st" : "x+47600-047900",
    "ts" : ISODate("1984-03-05T13:00:00Z"),
    "position" : {
      "type" : "Point",
      "coordinates" : [ -47.9, 47.6 ]
    },
    "elevation" : 9999,
    "callLetters" : "VCSZ",
    "qualityControlProcess" : "V020",
    "dataSource" : "4",
    "type" : "FM-13",
    "airTemperature" : { "value" : -3.1, "quality" : "1" },
    "dewPoint" : { "value" : 999.9, "quality" : "9" },
    "pressure" : { "value" : 1015.3, "quality" : "1" },
    "wind" : {
      "direction" : { "angle" : 999, "quality" : "9" },
      "type" : "9",
      "speed" : { "rate" : 999.9, "quality" : "9" }
    },
    "visibility" : {
      "distance" : { "value" : 999999, "quality" : "9" },
      "variability" : { "value" : "N", "quality" : "9" }
    },
    "skyCondition" : {
      "ceilingHeight" : { "value" : 99999, "quality" : "9", "determination" : "9" },
      "cavok" : "N"
    },
    "sections" : [ "AG1" ],
    "precipitationEstimatedObservation" : { "discrepancy" : "2",
    "estimatedWaterDepth" : 999 }
}

The following pipeline stages add a metaData field and use $project to include or exclude the remaining fields in the document:以下管道阶段添加metaData字段，并使用$project包含或排除文档中的其余字段：

{ $addFields: {
    metaData: {
      "st": "$st",
      "position": "$position",
      "elevation": "$elevation",
      "callLetters": "$callLetters",
      "qualityControlProcess": "$qualityControlProcess",
      "type": "$type"
    }
  },
},
{ $project: {
    _id: 1,
    ts: 1,
    metaData: 1,
    dataSource: 1,
    airTemperature: 1,
    dewPoint: 1,
    pressure: 1,
    wind: 1,
    visibility: 1,
    skyCondition: 1,
    sections: 1,
    precipitationEstimatedObservation: 1
  }
}

Use the timeseries option with the $out aggregation stage将时间序列选项与$out聚合阶段一起使用

The example below uses the db.collection.aggregate() helper method. 下面的示例使用db.collection.aggregate()辅助方法。For the aggregation stage syntax, see $out. For a full explanation of the time series options, see the Time Series Field Reference.有关聚合阶段语法，请参阅$out。有关时间序列选项的完整说明，请参阅时间序列字段参考。

db.weather_data.aggregate([
  {
     $addFields: {
       metaData: {
         "st": "$st",
         "position": "$position",
         "elevation": "$elevation",
         "callLetters": "$callLetters",
         "qualityControlProcess": "$qualityControlProcess",
         "type": "$type"
       }
     },
  }, {
     $project: {
        _id: 1,
        ts: 1,
        metaData: 1,
        dataSource: 1,
        airTemperature: 1,
        dewPoint: 1,
        pressure: 1,
        wind: 1,
        visibility: 1,
        skyCondition: 1,
        sections: 1,
        precipitationEstimatedObservation: 1
     }
  }, {
     $out: {
       db: "mydatabase",
       coll: "weathernew",
       timeseries: {
         timeField: "ts",
         metaField: "metaData"
       }
     }
  }
])