USE INDEX does not find the index

Thanks @geraldss, but it did not seem to make any difference.

This:

select day_utc, count(*) as count from stats use index(day_utc_index) where day_utc is not null  group by day_utc;

still gives the error: “View Index not found day_utc_index”

and this:

select day_utc, count(*) as count from stats where day_utc is not null  group by day_utc;

now takes about 9 seconds to execute instead of 8 on the same 75,000 documents.

Here is the output of explain:

    n1ql> explain select day_utc, count(*) as count from stats where day_utc is not null  group by day_utc;
{
    "requestID": "7dc52a76-b87f-4848-a5a6-713b33a4b27a",
    "signature": "json",
    "results": [
        {
            "#operator": "Sequence",
            "~children": [
                {
                    "#operator": "PrimaryScan",
                    "index": "#primary",
                    "keyspace": "stats",
                    "namespace": "default",
                    "using": "view"
                },
                {
                    "#operator": "Parallel",
                    "~child": {
                        "#operator": "Sequence",
                        "~children": [
                            {
                                "#operator": "Fetch",
                                "keyspace": "stats",
                                "namespace": "default"
                            },
                            {
                                "#operator": "Filter",
                                "condition": "((`stats`.`day_utc`) is not null)"
                            },
                            {
                                "#operator": "InitialGroup",
                                "aggregates": [
                                    "count(*)"
                                ],
                                "group_keys": [
                                    "(`stats`.`day_utc`)"
                                ]
                            }
                        ]
                    }
                },
                {
                    "#operator": "IntermediateGroup",
                    "aggregates": [
                        "count(*)"
                    ],
                    "group_keys": [
                        "(`stats`.`day_utc`)"
                    ]
                },
                {
                    "#operator": "FinalGroup",
                    "aggregates": [
                        "count(*)"
                    ],
                    "group_keys": [
                        "(`stats`.`day_utc`)"
                    ]
                },
                {
                    "#operator": "Parallel",
                    "~child": {
                        "#operator": "Sequence",
                        "~children": [
                            {
                                "#operator": "InitialProject",
                                "result_terms": [
                                    {
                                        "expr": "(`stats`.`day_utc`)"
                                    },
                                    {
                                        "as": "count",
                                        "expr": "count(*)"
                                    }
                                ]
                            },
                            {
                                "#operator": "FinalProject"
                            }
                        ]
                    }
                }
            ]
        }
    ],
    "status": "success",
    "metrics": {
        "elapsedTime": "20.874533ms",
        "executionTime": "20.694588ms",
        "resultCount": 1,
        "resultSize": 2882
    }
}

Another data point:

select * from system:indexes;

does not show day_utc_index as one of the indexes.