mongodb - 如何在 mongodb 上查找和取消设置相同的子字段值

Question

我在 mongodb 中有 100 万个文档。我想查找并取消设置相同的字段。你能给我一个方法或想法吗？

我的文档是这样的:

{
        "regions" : [ 
            {"id" : "1", "name" : "World"}, 
            {"id" : "10370","name" : "South America"}, 
            {"id" : "1426","name" : "Suriname"}
        ]
    }
    {
        "regions" : [ 
            {"id" : "1", "name" : "World"}, 
            {"id" : "10370","name" : "South America"}, 
            {"id" : "1426","name" : "Suriname"}
        ]
    }
    {
        "regions" : [ 
            {"id" : "1","name" : "World"}, 
            {"id" : "1734","name" : "USA"}, 
            {"id" : "1136","name" : "Pennsylvania"}, 
            {"id" : "16962","name" : "Greater Philadelphia area"}, 
        ]
    }
    {
        "regions" : [ 
            {"id" : "1","name" : "World"}, 
            {"id" : "1734","name" : "USA"}, 
            {"id" : "1136","name" : "Pennsylvania"}, 
            {"id" : "16962","name" : "Greater Philadelphia area"}, 
        ]
    }
    {
    "regions" : [ 
        {"id" : "1","name" : "World"}, 
        {"id" : "34964","name" : "Oceania"}, 
        {"id" : "15","name" : "Australia"}, 
        {"id" : "470","name" : "Western Australia"}, 
        {"id" : "36282","name" : "Perth"}, 
      ]
   }

我该如何改变:

{
        "regions" : [ 
            {"id" : "1", "name" : "World"}, 
            {"id" : "10370","name" : "South America"}, 
            {"id" : "1426","name" : "Suriname"}
        ]
    }
    {
        "regions" : [ 
            {"id" : "1","name" : "World"}, 
            {"id" : "1734","name" : "USA"}, 
            {"id" : "1136","name" : "Pennsylvania"}, 
            {"id" : "16962","name" : "Greater Philadelphia area"}, 
        ]
    }
    {
"regions" : [ 
    {"id" : "1","name" : "World"}, 
    {"id" : "34964","name" : "Oceania"}, 
    {"id" : "15","name" : "Australia"}, 
    {"id" : "470","name" : "Western Australia"}, 
    {"id" : "36282","name" : "Perth"}, 
   ]
  }

提前感谢您的回答和兴趣。

更新: 我正在尝试这段代码:

db.collection.aggregate(
 {"$group":{"_id": {"id": "$regions.id","name": "$regions.name"},}},
 {"$group":{"_id":ObjectId(),"regions": { "$push": {"id": "$_id.id","name": $_id.name"}}}},
 {"$unwind": "$regions"},
 {"$out": "newcollection"}
)

它给出了这个错误: "errmsg": "insert for $out failed: { connectionId: 111, err:\"E11000 duplicate key error collection: collection.tmp.agg_out.12 index: id dup key: { : ObjectId( '5767f378ff8f5e9302d95bc8') }\", code: 11000, n: 0, ok: 1.0 }",

我怎样才能给一个唯一的 key ？

Answer 1

使用聚合，如果你按数组元素分组，你可以摆脱重复的区域。这样的事情应该有帮助吗？

db.regs.aggregate([{$group:{"_id":{id:"$regions.id",name:"$regions.name"}}}]).pretty()