Broken E11000 duplicate key error when unique index contains collation

The E11000 duplicate key exception contains wrong details which sometimes lead to the exception on the driver since we cannot parse it.

Consider the following queries:

// prepare collection

db.coll.createIndex( { "testValue" : 1 }, { unique : true, collation: { locale : 'sv', strength : 1, numericOrdering : true } } )

{

        "createdCollectionAutomatically" : true,

        "numIndexesBefore" : 1,

        "numIndexesAfter" : 2,

        "commitQuorum" : 1,

        "ok" : 1

}

Then, try to add two the same documents one by one:

• More simple case:

  // 1 attempt

  db.coll.insertOne({ "testValue": "def"})

  {

  "acknowledged" : true,

  "insertedId" : ObjectId("5e695401da7e6a4f1b712884")

  }

  // 2 attempt

  db.coll.insertOne({ "testValue": "def"})

  {"t":{"$date":"2020-03-11T21:11:30.702Z"},"s":"E", "c":"QUERY", "id":0,"ctx":"js","msg":"{}","attr":{"message":"WriteError({\n\t\"index\" : 0,\n\t\"code\" : 11000,\n\t\"errmsg\" : \"E11000 duplicate key error collection: test.coll index: testValue_1 dup key: { testValue: \\\"/13\\\" }\",\n\t\"op\" : {\n\t\t\"_id\" : ObjectId(\"5e695402da7e6a4f1b712885\"),\n\t\t\"testValue\" : \"def\"\n\t}\n}) :\nWriteError({\n\t\"index\" : 0,\n\t\"code\" : 11000,\n\t\"errmsg\" : \"E11000 duplicate key error collection: test.coll index: testValue_1 dup key: { testValue: \\\"/13\\\" }\",\n\t\"op\" : {\n\t\t\"_id\" : ObjectId(\"5e695402da7e6a4f1b712885\"),\n\t\t\"testValue\" : \"def\"\n\t}\n})\nWriteError@src/mongo/shell/bulk_api.js:458:48\nmergeBatchResults@src/mongo/shell/bulk_api.js:855:49\nexecuteBatch@src/mongo/shell/bulk_api.js:919:13\nBulk/this.execute@src/mongo/shell/bulk_api.js:1163:21\nDBCollection.prototype.insertOne@src/mongo/shell/crud_api.js:264:9\n@(shell):1:1"}}

  This case contains only issue with wrong exception details:

  testValue_1 dup key: { testValue: \\\"/13\\\" }

• Worse case:

  // 1 attempt

  db.coll.insertOne({ "testValue": "abcdefghijkl123456789"})

  {

  "acknowledged" : true,

  "insertedId" : ObjectId("5e695418da7e6a4f1b712886")

  }

  // 2 attempt

  db.coll.insertOne({ "testValue": "abcdefghijkl123456789"})

  {"t":{"$date":"2020-03-11T21:11:53.807Z"},"s":"E", "c":"QUERY", "id":0,"ctx":"js","msg":"{}","attr":{"message":"WriteError({\n\t\"index\" : 0,\n\t\"code\" : 11000,\n\t\"errmsg\" : \"E11000 duplicate key error collection: test.coll index: testValue_1 dup key: { testValue: \\\")+-/13579;=?\\u000f�\\r9\\u000fe��\\\" }\",\n\t\"op\" : {\n\t\t\"_id\" : ObjectId(\"5e695419da7e6a4f1b712887\"),\n\t\t\"testValue\" : \"abcdefghijkl123456789\"\n\t}\n}) :\nWriteError({\n\t\"index\" : 0,\n\t\"code\" : 11000,\n\t\"errmsg\" : \"E11000 duplicate key error collection: test.coll index: testValue_1 dup key: { testValue: \\\")+-/13579;=?\\u000f�\\r9\\u000fe��\\\" }\",\n\t\"op\" : {\n\t\t\"_id\" : ObjectId(\"5e695419da7e6a4f1b712887\"),\n\t\t\"testValue\" : \"abcdefghijkl123456789\"\n\t}\n})\nWriteError@src/mongo/shell/bulk_api.js:458:48\nmergeBatchResults@src/mongo/shell/bulk_api.js:855:49\nexecuteBatch@src/mongo/shell/bulk_api.js:919:13\nBulk/this.execute@src/mongo/shell/bulk_api.js:1163:21\nDBCollection.prototype.insertOne@src/mongo/shell/crud_api.js:264:9\n@(shell):1:1"}}

  In this case we will see the wrong error part:

  testValue_1 dup key: { testValue: \\\")+-/13579;=?\\u000f�\\r9\\u000fe��\\\" }

  but the worst thing that we won't be able to parse this error on the driver side. And as a result this error will trigger a new deserialization exception which will fully hide the original one.

It looks like this ticket is related to https://jira.mongodb.org/browse/SERVER-26050