COUCHBASE - how to create primary index for N1QL

C:\Users\andriypa>cbq
Couchbase query shell connected to http://localhost:8093/ . Type Ctrl-D to exit.
cbq> CREATE PRIMARY INDEX ON `default`;
{
    "requestID": "65230d77-9d8f-4f13-9590-776ad6309f9c",
    "signature": null,
    "results": [
    ],
    "status": "success",
    "metrics": {
        "elapsedTime": "3.1251858s",
        "executionTime": "3.1241875s",
        "resultCount": 0,
        "resultSize": 0
    }
}