MongoDB DuplicateKeyException

Question

WriteConcern detected an error 'insertDocument :: caused by :: 11000 E11000 duplicate key error index: develop.Test.$AppId_1_UserId_1_Type_1__sub_1__key_1  dup key: { ... }'. (Response was { "ok" : 1, "code" : 11000, "err" : "insertDocument :: caused by :: 11000 E11000 duplicate key error index: develop.Test.$AppId_1_UserId_1_Type_1__sub_1__key_1  dup key: {...}).

I'm getting the above error when trying to insert a new entry into my collection. The thing that is confusing me is my key is a Guid id field. The entity has AppId and UserId fields but those aren't supposed to be the key and shouldn't have to be unique.

Right before I save the Id is just all zeroes. After it is set to a unique Guid, but the save call throws the MongoDuplicateKey error. Maybe it's because I'm new to Mongo but I don't understand this any help would be appreciated.

Update

Output of get Indexes

{
    "0" : {
        "v" : 1,
        "key" : {
            "_id" : 1
        },
        "name" : "_id_",
        "ns" : "develop.Test"
    },
    "1" : {
        "v" : 1,
        "unique" : true,
        "key" : {
            "AppId" : 1,
            "UserId" : 1,
            "Type" : 1,
            "_sub" : 1,
            "_key" : 1
        },
        "name" : "AppId_1_UserId_1_Type_1__sub_1__key_1",
        "ns" : "develop.Test"
    },
    "2" : {
        "v" : 1,
        "key" : {
            "Type" : 1,
            "_sub" : 1,
            "_g" : 1
        },
        "name" : "Type_1__sub_1__g_1",
        "ns" : "develop.Test"
    }
}

can you show us the output of db.collection.getIndexes()

Sede
– Sede

2015-07-28 18:19:43 +00:00
Commented Jul 28, 2015 at 18:19 — Sede
– Sede, Commented Jul 28, 2015 at 18:19

Sede · Accepted Answer · 2015-07-28 19:09:42Z

2

You have a unique compound indexes on the AppId, UserId, Type, sub and key fields that is why you are getting this error.

"1" : {
        "v" : 1,
        "unique" : true,
        "key" : {
            "AppId" : 1,
            "UserId" : 1,
            "Type" : 1,
            "_sub" : 1,
            "_key" : 1
        },
        "name" : "AppId_1_UserId_1_Type_1__sub_1__key_1",
        "ns" : "develop.Test"
    },

Now how to solve the problem?

If you didn't create it so perhaps you co-worker or someone did. In this case you don't drop the index without talking to them.

You may want to drop the index using db.collection.dropIndex(index) method

db.collection.dropIndex({ AppId: 1, UserId: 1, Type: 1, _sub: 1, _key: 1 })

edited Jul 28, 2015 at 19:09

answered Jul 28, 2015 at 18:35

Sede

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1 Comment

nastassiar Over a year ago

It turned out I just had to change _key to Key! The subject field had a [BsonElement("_sub")] tag but there wasn't one for Key so _key was always null. Thanks for pointing me in the right direction!

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