Where Clause analysis gives warnings when ANN sort used with no filtering

[amorton]

Not sure if this is an fault or expected behaviour, but if I send this query:

{
    "find": {
        "sort": 
            {
                "comment_vector": [0.45, 0.09, 0.01, 0.2, 0.11]
            },
            "options" : { "limit" : 1}
    }
}

I get this back, and it has a warning that no filtering was used. Which is true, but we had an ANN sort. It may be better if we had a specific warning about ANN sort with no filter ? We need to decide before changing.

{
    "data": {
        "documents": [
            {
                "comment_vector": [
                    0.45,
                    0.09,
                    0.01,
                    0.2,
                    0.11
                ],
                "comment": "comment about cheese and monkeys",
                "key": "doc 1"
            }
        ],
        "nextPageState": null
    },
    "status": {
        "warnings": [
            {
                "errorCode": "ZERO_FILTER_OPERATIONS",
                "message": "Zero filters were provided in the filer for this query. \n\nProviding zero filters will return all rows in the table, which may have poor performance when the table is large. For the best performance, include one or more filters using the primary key or indexes.\n\nThe table demo.vector_5 has the primary key: key(text).\nAnd has indexes on the columns: comment_vector.\n\nThe query was executed without taking advantage of the primary key or indexes on the table, this can have performance implications on large tables.\n\nSee documentation at XXXX for best practices for filtering.",
                "family": "REQUEST",
                "scope": "WARNING",
                "title": "Zero operations provided in query filter",
                "id": "0502d938-5746-41e6-bd23-20ca1bbef548"
            }
        ],
        "projectionSchema": {
            "comment_vector": {
                "type": "vector",
                "dimension": 5
            },
            "comment": {
                "type": "text"
            },
            "key": {
                "type": "text"
            }
        }
    }
}