Field caps api incorrect reports a doc values only scaled float field as not searchable

[martijnvg]

Reproduction:

PUT /index1
{
    "settings": {
        "index.mode": "time_series",
        "time_series": {
                "start_time": "2000-01-01T00:00:00Z",
                "end_time": "2099-12-31T23:59:59Z"
            },
            "routing_path": [
                "field1"
            ]
    },
    "mappings": {
        "properties": {
            "field1": {
                "type": "keyword",
                "time_series_dimension": true
            },
            "field2": {
                "type": "long",
                "time_series_metric": "gauge"
            },
            "field3": {
                "type": "scaled_float",
                "time_series_metric": "gauge",
                "scaling_factor": 100
            }
        }
    }
}

GET /index1/_field_caps/?fields=field*

Field caps response:

{
    "indices": [
        "index1"
    ],
    "fields": {
        "field1": {
            "keyword": {
                "type": "keyword",
                "metadata_field": false,
                "searchable": true,
                "aggregatable": true,
                "time_series_dimension": true
            }
        },
        "field3": {
            "scaled_float": {
                "type": "scaled_float",
                "metadata_field": false,
                "searchable": false,
                "aggregatable": true,
                "time_series_metric": "gauge"
            }
        },
        "field2": {
            "long": {
                "type": "long",
                "metadata_field": false,
                "searchable": true,
                "aggregatable": true,
                "time_series_metric": "gauge"
            }
        }
    }
}

Both fields aren't indexed by default (because marked as time series metric), but do have doc values.
Which means the fields are searchable, but slow. However for the scaled float field, field caps reports that it isn't searchable. Which isn't correct. Field caps should report that field3 is searchable.

Looking at the mapping code the ScaledFloatFieldType extends from MappedFieldType and that returns searchable only for indexed fields. Either MappedFieldType should overwrite the isSearchable() method or extend from NumberFieldType.

[elasticsearchmachine]

Pinging @elastic/es-analytics-geo (Team:Analytics)

[elasticsearchmachine]

Pinging @elastic/es-search (Team:Search)

[lalit-satapathy]

Is this fixed as part of 8.10?

[martijnvg]

Yes, that is fixed in 8.10. The PR got merged before the 8.10 branch was cut.

[martijnvg]

Fixed via #97724