TSDB: disable _tsid in composite aggregation

[weizijun]

in composite aggregation, group by _tsid will return the error:

{
  "error" : {
    "root_cause" : [
      {
        "type" : "unsupported_operation_exception",
        "reason" : null
      }
    ],
    "type" : "unsupported_operation_exception",
    "reason" : null,
    "suppressed" : [
      {
        "type" : "illegal_state_exception",
        "reason" : "Failed to close the XContentBuilder",
        "caused_by" : {
          "type" : "i_o_exception",
          "reason" : "Unclosed object or array found"
        }
      }
    ]
  },
  "status" : 500
}

reproduce:

PUT test
{
  "settings": {
    "index": {
      "time_series.start_time": 1,
      "time_series.end_time": 99999999999,
      "mode": "time_series",
      "routing_path": [
        "test"
      ]
    }
  },
  "mappings": {
    "properties": {
      "test": {
        "type": "keyword",
        "time_series_dimension": true
      }
    }
  }
}

POST test/_doc?refresh
{
  "test" : "test",
  "@timestamp" : 2
}

GET test/_search
{
  "aggs": {
    "1": {
      "composite": {
        "sources": [
          {
            "2": {
              "terms": {
                "field": "_tsid"
              }
            }
          }
        ]
      }
    }
  }
}

The reason why failed is that in InternalComposite.getKeyAsString, it will return a string for after key, but _tsid is a Map.

I think _tsid is not suitable for composite aggregation, so I add a check to failed composite aggregation with _tsid.

[elasticmachine]

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

[nik9000]

I think we want _tsid to work in composite aggregation. It's the sort key of the index so it's the most efficient way to run composite. @imotov, do you agree?

[weizijun]

I think we want _tsid to work in composite aggregation. It's the sort key of the index so it's the most efficient way to run composite. @imotov, do you agree?

is hard to use _tsid in composite aggregation, because of the after key need a string value. if we can implement the _tsid string format, it is ok to use in composite aggregation.

now, _tsid in composite aggregation will throw an unexpected exception.

[nik9000]

Yeah. I think @csoulios will try and fix it soon.

[csoulios]

@weizijun PR #81998 should fix issues with composite aggregation

[weizijun]

@weizijun PR #81998 should fix issues with composite aggregation

yeah, I see, thank you!

[weizijun]

the exception fixed in #81998