Migrate Data into a Time Series Collection with an Aggregation Pipeline使用聚合管道将数据迁移到时间序列集合中

Create a metadata field.创建元数据字段。

If your collection doesn't include a field you can use to identify each series, transform your data to define one. In this example, the metaData field becomes the metaField of the time series collection that you create.如果集合不包括可用于标识每个系列的字段，请转换数据以定义一个。在此示例中，metaData字段将成为您创建的时间序列集合的metaField。

The pipline below performs the following operations:下面的管线执行以下操作：

• Uses $addFields to add a metaData field to the weather_data collection.使用$addFields将元数据字段添加到weather_data集合中。
• Uses $project to include or exclude the remaining fields in the document.使用$project包含或排除文档中的其余字段。

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
   }
}
])

Create your time series collection and insert your data.创建时间序列集合并插入数据。

Add an $out aggregation stage to your pipeline to create a time series collection and insert your data into it. The pipeline below performs the following operations:将$out聚合阶段添加到管道中，以创建时间序列集合并将数据插入其中。下面的管道执行以下操作：

• Uses $out with the timeseries option to create a weathernew time series collection in the mydatabase database.使用$out和timeseries选项在mydatabase数据库中创建weathernew时间序列集合。
• Defines the metaData field as the metaField of the weathernew collection.将metaData字段定义为weathernew集合的metaField。

• Defines the ts field as the timeField of the weathernew collection.将ts字段定义为weathernew集合的timeField。

  Note

  The timeField of a time series collection must be a date type.时间序列集合的timeField必须是date类型。

{
   $out: {
      db: "mydatabase",
      coll: "weathernew",
      timeseries: {
         timeField: "ts",
         metaField: "metaData",
         granularity: "seconds"
      }
   }
}

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。

Review your data.检查数据。

After you run this aggregation pipeline, you can use findOne() to view a document in your weathernew time series collection:运行此聚合管道后，您可以使用findOne()查看weathernew时间序列集合中的文档：

db.weathernew.findOne()

The operation returns the following document:该操作返回以下文档：

   {
      _id: ObjectId("5553a998e4b02cf7151190b8"),
      ts: ISODate("1984-03-05T13:00:00Z"),
      metaData: {
         st: "x+47600-047900",
         position: {
            type: "Point",
            coordinates: [ -47.9, 47.6 ]
         },
         elevation: 9999,
         callLetters: "VCSZ",
         qualityControlProcess: "V020",
         type: "FM-13"
      },
      dataSource: "4",
      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 }
   }