Fix NPE when indexing a document that just has been deleted in a tsdb index

[martijnvg]

Sometimes a segment only contains tombstone documents. In that case, loading min and max @timestamp field values can result into NPE. Because these documents don't have a @timestamp field.

This change fixes that by checking for the existence of the @timestamp field in the a segment's field infos.

Reproduction of the issue:

Create tsdb index:

PUT weather_sensors
{
    "mappings": {
        "properties": {
            "@timestamp": {
                "type": "date"
            },
            "humidity": {
                "type": "half_float",
                "time_series_metric": "gauge"
            },
            "location": {
                "type": "keyword",
                "time_series_dimension": true
            },
            "sensor_id": {
                "type": "keyword",
                "time_series_dimension": true
            },
            "temperature": {
                "type": "half_float",
                "time_series_metric": "gauge"
            }
        }
    },
    "settings": {
        "index": {
            "time_series": {
                "start_time": "2000-01-01T00:00:00.000Z",
                "end_time": "2099-12-31T23:59:59.999Z"
            },
            "routing_path": [
                "sensor_id",
                "location"
            ],
            "mode": "time_series",
            "codec": "best_compression",
            "number_of_shards": "1"
        }
    }
}

Index document:

POST weather_sensors/_doc
{
  "@timestamp": "2023-05-31T08:41:15.000Z",
  "sensor_id": "SYKENET-000001",
  "location": "swamp",
  "temperature": 32.4,
  "humidity": 88.9
}

Delete that document:

DELETE weather_sensors/_doc/crxuhC8WO3aVdhvtAAABiHD35_g

Index same document again:

POST weather_sensors/_doc
{
  "@timestamp": "2023-05-31T08:31:15.000Z",
  "sensor_id": "SYKENET-000001",
  "location": "swamp",
  "temperature": 42.4,
  "humidity": 88.9
}

Last api call results in the following error:

{
    "error": {
        "root_cause": [
            {
                "type": "null_pointer_exception",
                "reason": "Cannot invoke \"org.apache.lucene.index.CompositeReaderContext.reader()\" because \"org.apache.lucene.index.LeafReader.getContext().parent\" is null"
            }
        ],
        "type": "null_pointer_exception",
        "reason": "Cannot invoke \"org.apache.lucene.index.CompositeReaderContext.reader()\" because \"org.apache.lucene.index.LeafReader.getContext().parent\" is null"
    },
    "status": 500
}

[elasticsearchmachine]

Hi @martijnvg, I've created a changelog YAML for you.

[elasticsearchmachine]

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

[elasticsearchmachine]

💚 Backport successful

Status	Branch	Result
✅	8.8