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将数据迁移到时间序列集合

在此页面上

  • 将数据迁移到时间序列集合
  • (可选)转换数据以创建元数据字段(如果不存在)。此字段不是必填字段。
  • 将时间序列选项与 $out 聚合阶段结合使用

要将现有集合中的数据迁移到时间序列集合,请在聚合管道中使用 $out 阶段。

1

如果原始数据集没有元数据字段,可使用 $addFields 聚合阶段添加元数据字段。

考虑使用以下格式的天气数据集合:

{
"_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 }
}

以下管道阶段添加了 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
}
}
2

下面的示例使用了 db.collection.aggregate() 助手方法。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"
}
}
}
])

运行该命令后,就会出现以下 weathernew 集合:

db.weathernew.findOne()
{
"_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 }
}

如果原始集合中有二级索引,请现在手动重新创建。如果集合在 1970-01-01T00:00:00.000Z 之前或 2038-01-19T03:14:07.000Z 之后包含 timeField 个值,MongoDB 会记录警告并禁用某些使用内部聚集索引的查询优化。在 timeField创建二级索引,以恢复查询性能并解决日志警告问题。

提示

另请参阅:

后退

向时间序列集合添加从节点索引