Getting the latest transform trigger time in a continuous transform

[cwwongaz (Wong Chun Wai)]

Hi, I am running a continuous transform at a 15-minute frequency to transform the data from index_A to index_B.

In the transform, I have set a 120s sync delay time to avoid missing the latest data. However, in the aggregation scripts, I have a function that would require finding out the time elapsed between the document @timestamp and the trigger time of the transformation.

That is, suppose the continuous transformation triggers at a time T, I would like to get the time T - doc[@timestamp].value in the Scripted metric aggregation i.e. init_script / map_script / reduce_script

My questions are:

1. As I cannot find a way to get the transformation triggers time T, I am currently using the System.currentTimeMillis() as the time T to get the time elapsed, however, I am concerned that the possible sync delay time will cause a difference in the script.

2. Is there any way to get the transformation triggers time T inside the Scripted metric aggregation? I have seen that the time_upper_bound_millis from the transform page, is this time ``time_upper_bound_millis` equal to the transformation triggers time I need? If it is, is there any way to get it in the Scripted metric aggregation?

Attached is the transform information.

{
  "id": "transform script",
  "version": "7.14.2",
  "create_time": -,
  "source": {
    "index": [
      "index_A"
    ],
    "query": {
      "bool": {
        "filter": [
          {
            "range": {
              "@timestamp": {
                "gte": "now-15m"
              }
            }
          }
        ]
      }
    }
  },
  "dest": {
    "index": "index_B",
    "pipeline": ""
  },
  "frequency": "15m",
  "sync": {
    "time": {
      "field": "@timestamp",
      "delay": "120s"
    }
  },
  "pivot": {
    "group_by": {
      
      }
    },
    "aggregations": {
      "@timestamp": {
        "max": {
          "field": "@timestamp"
        }
      },
      "script_field": {
        "scripted_metric": {
          "combine_script": "return state",
          "init_script": {
            "id": "some_init_script"
          },
          "map_script": {
            "id": "some_map_script"
          },
          "params": {
            
          },
          "reduce_script": {
            "id": "some_reduce_script"
          }
        }
      }
    }
  },
  "description": "DEMO",
  "settings": {
    "max_page_search_size": 10000
  }
}