Hello,
In transforms can you specify an index template for mappings?  Or set the date format?  My source index has a timestamp properly formatted using strict_date_optional_time||epoch_millis.  When it goes to the transform index I lose the formatting.  I have the following settings in a transform:
      "dest" : {
        "index" : "transform_test",
        "pipeline": "date_format_transform"
Where the pipeline date_formatt_transform turns the timestamp into strict_date_optional_time||epoch_millis However everytime I check the mappings of my new index my date is just "date" with no formatting:
        "timestamp" : {
          "type" : "date"
        },
I tried specifying the date formatting directly as well:
     "timestamp" : {
        "date_histogram" : {
          "field" : "timestamp",
          "format" : "strict_date_optional_time||epoch_millis",
          "calendar_interval" : "1d"
        }
But I get the error:
[data_frame_date_histogram_group] unknown field [format]
Please advise