Change exceptions to IllegalArgumentException in GroupingDocValuesSelector

[iverase]

The exceptions happens when user provides unsupported doc value types (either the type is wrong or it is multi-valued) so the rest status code should be 400 instead of 500.

Current error:

{
  "error": {
    "root_cause": [
      {
        "type": "illegal_state_exception",
        "reason": "failed to extract doc:0, the grouping field must be single valued"
      }
    ],
    "type": "search_phase_execution_exception",
    "reason": "all shards failed",
    "phase": "query",
    "grouped": true,
    "failed_shards": [
      {
        "shard": 0,
        "index": "test",
        "node": "6lqb2ehXRrOdVMeXe_7PHg",
        "reason": {
          "type": "illegal_state_exception",
          "reason": "failed to extract doc:0, the grouping field must be single valued"
        }
      }
    ],
    "caused_by": {
      "type": "illegal_state_exception",
      "reason": "failed to extract doc:0, the grouping field must be single valued",
      "caused_by": {
        "type": "illegal_state_exception",
        "reason": "failed to extract doc:0, the grouping field must be single valued"
      }
    }
  },
  "status": 500
}

[elasticsearchmachine]

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

[ChrisHegarty]

Lgtm

[javanna]

Thanks for fixing this, did you see this in practice? I wonder how users are going to experience this error. Is there anything else we can do to fail earlier?

[iverase]

Is there anything else we can do to fail earlier?

I wondered the same. The issue here is for multi-value fields as the only way to check for it is looking into the actua data. I am not sure if we can check before it happens.

[javanna]

Agreed @iverase we don't make distinctions around number of values in Elasticsearch, sounds like there isn't much we can do about this other than changing the status code. The error is pretty clear though, it should be easy to understand. Maybe the id of the doc is confusing, but we don't have the _id available when the error is thrown.

[elasticsearchmachine]

💔 Backport failed

Status	Branch	Result
❌	8.19	Commit could not be cherrypicked due to conflicts

You can use sqren/backport to manually backport by running backport --upstream elastic/elasticsearch --pr 128348