mongodb - 蒙哥错误: E11000 duplicate key error collection for unique compound index

Question

Question is related to unique compound index unlike other such questions which have unique index only. I also have sparse: true for the indexes.

我的收藏中有以下索引

[
  {
    "v": 2,
    "key": {
      "_id": 1
    },
    "name": "_id_",
    "ns": "somedb.votes"
  },
  {
    "v": 2,
    "key": {
      "answerId": 1
    },
    "name": "answerId_1",
    "ns": "somedb.votes",
    "sparse": true,
    "background": true
  },
  {
    "v": 2,
    "key": {
      "questionId": 1
    },
    "name": "questionId_1",
    "ns": "somedb.votes",
    "sparse": true,
    "background": true
  },
  {
    "v": 2,
    "unique": true,
    "key": {
      "answerId": 1,
      "votedBy": 1
    },
    "name": "answerId_1_votedBy_1",
    "ns": "somedb.votes",
    "sparse": true,
    "background": true
  },
  {
    "v": 2,
    "unique": true,
    "key": {
      "questionId": 1,
      "votedBy": 1
    },
    "name": "questionId_1_votedBy_1",
    "ns": "somedb.votes",
    "sparse": true,
    "background": true
  }
]

我在集合中有以下文档

{
  "_id": ObjectId("59fdd3ce915511329553dfaa"),
  "updatedAt": ISODate("2017-11-04T14:54:22.110Z"),
  "votedAt": ISODate("2017-11-04T14:50:54.681Z"),
  "questionId": ObjectId("59fc77e45a857465a90339cc"),
  "value": -1,
  "votedBy": ObjectId("59fc4274aa686d39abe5d58a"),
  "type": "QuestionVote",
  "__v": 0
}

---

现在当我尝试执行以下操作时

db.votes.insert({ questionId: ObjectId("59fc798d5a857465a90339cf"), value: -1, votedBy: ObjectId("59fc4274aa686d39abe5d58a"), type: 'QuestionVote', _id: ObjectId("5a003240bfd8194a")02 })

出现以下错误

E11000 duplicate key error collection: somedb.votes index: answerId_1_votedBy_1 dup key: { : null, : ObjectId('59fc4274aa686d39abe5d58a') }
WriteResult({
  "nInserted": 0,
  "writeError": {
    "code": 11000,
    "errmsg": "E11000 duplicate key error collection: somedb.votes index: answerId_1_votedBy_1 dup key: { : null, : ObjectId('59fc4274aa686d39abe5d58a') }"
  }
})

我不明白原因。索引是稀疏和复合。但错误只是因为存在相同的 votedBy 字段。

即执行以下操作，

db.votes.insert({votedBy: ObjectId("59fc4274aa686d39abe5d58a")})

即使 votedBy 对象没有显式索引，我也会收到以下错误。

E11000 duplicate key error collection: somedb.votes index: answerId_1_votedBy_1 dup key: { : null, : ObjectId('59fc4274aa686d39abe5d58a') }
WriteResult({
  "nInserted": 0,
  "writeError": {
    "code": 11000,
    "errmsg": "E11000 duplicate key error collection: somedb.votes index: answerId_1_votedBy_1 dup key: { : null, : ObjectId('59fc4274aa686d39abe5d58a') }"
  }
})

引用:复合指数 - https://docs.mongodb.com/manual/core/index-compound/#compound-indexes

Answer 1

这可能是因为同一个集合有旧索引，正如使用此方法从控制台检查的那样:

db.votes.getIndexes()

然后放下它们:

db.votes.dropIndexes()

在您定义模式的应用程序中，您应该像这样索引复合索引:

<your_schema_name>.index({
  field1: 1,
  field2:1,
  etc...
},{
    unique: true,
    sparse: true  //N.B:(sparse:true) is not a must for the compound unique indexing to work
});

现在重新启动您的应用程序，最后一个最终所需的复合索引应该可以工作。

额外说明

我在创建唯一索引时发现，您的数据库中已经有违反此创建的记录，它不起作用。

来自 node.js:

从我的 mongoose 驱动程序调试器中，我可以看到驱动程序试图索引

Mongoose: <my_collection>.ensureIndex({ field1: 1, 'field2.xx.xxx': 1, field: 3 }, { unique: true, background: true })

我没有从节点收到任何错误，但是当我使用 getIndexes() 方法从控制台检查时，我没有找到新的索引。

从控制台:

我试着确保索引

db.<my_collection>.ensureIndex({ field1: 1, 'field2.xx.xxx': 1, field: 3 }, { unique: true, background: true })

我收到违反此索引的记录错误

{
    "ok" : 0,
    "errmsg" : "E11000 duplicate key error collection: <db_name>.<collection_name> index: field1_xxx.xxxx.xxxx_1_filed2_1 dup key: { : \"xxx\", : \"xxxx\", : ObjectId('xxx') }",
    "code" : 11000
}

结论

如果有任何记录违反了新的所需索引，唯一索引(复合或非复合)将不起作用，即使您删除所有索引并像我之前提到的那样重试重新索引也是如此。