Error E11000 in creating MongoDB unique index-CodePudding

I have a MongoDB(v 5.0.6) collection with the following data:

[{
  "_id": {
    "$oid": "63bc06e6aa310000d6004a68"
  },
  "key": "title",
  "label": "title",
  "type": "text",
  "searchable": 0
},{
  "_id": {
    "$oid": "63bc06e6aa310000d6004a69"
  },
  "key": "attribution",
  "label": "attribution",
  "type": "text",
  "searchable": 0
},{
  "_id": {
    "$oid": "63bc06e6aa310000d6004a6a"
  },
  "key": "description",
  "label": "description",
  "type": "text",
  "searchable": 0
},{
  "_id": {
    "$oid": "63bc06e6aa310000d6004a6b"
  },
  "key": "publisher",
  "label": "publisher",
  "type": "text",
  "searchable": 0
},{
  "_id": {
    "$oid": "63bc06e6aa310000d6004a6c"
  },
  "key": "published",
  "label": "published",
  "type": "number",
  "searchable": 0
},{
  "_id": {
    "$oid": "63bc06e6aa310000d6004a6d"
  },
  "key": "author",
  "label": "author",
  "type": "text",
  "searchable": 0
}]

Now I want to set up an unique index on the key (text) field. But each time I try to create the index, it produces this error:

Index build failed: 64014369-44e7-4371-976a-25f0aed89614: Collection db.collection ( c9b12814-686b-4603-8e90-bba31f67d930 ) :: caused by :: E11000 duplicate key error collection: db.collection index: key_text dup key: { _fts: "publish", _ftsx: 1.0 }

I have no idea why this appears. As the error indicates, there is no value matching 'publish' in the data. Can anyone please take a look into it and help? Thanks in advance for going through this far and some more if you can point the solution.

CodePudding user response：

Now I want to set up an unique index on the key (text) field.

There are no "text" fields in MongoDB. Field types are listed there: https://www.mongodb.com/docs/manual/reference/bson-types/ and key is a "string".

The index type is one of:

asc
desc
geospatial
fulltext

You are selecting the later, which is described here https://www.mongodb.com/docs/manual/core/index-text/

It makes very little sense to create unique full-text index. It will violate uniqueness if at least one word (post-stemed) appears in another document. In your case it's published and publisher. The common stem is publish.

Pleasae use one of asc or desc types to build unique index for the whole key. It will violate uniqueness only when keys are identical.

CodePudding user response：

I used console to run this command and it worked (index reflected in compass too):

db.<collection_name>.createIndex( { "key" : 1 }, { unique : true } )

Hope it helps someone.