Add new relations after creating the mapping

[iamash (Yiwei)]

Hi, I'm currently having the same question as #103827
Say I've already created a relation in the mapping:

PUT my_index
{
  "mappings": {
    "_doc": {
      "properties": {
        "my_join_field": { 
          "type": "join",
          "relations": {
            "question": "answer" 
          }
        }
      }
    }
  }
}

Now, if I want to add another child named "Comment" to the current parent question, is there any way that I can achieve this?
I know that once you create the mapping, you cannot update it, but I also saw this on join dataytpe page:

So please help

[abdon (Abdon Pijpelink)]

I would expect the following to work, to update the mappings with the new comment child type:

PUT my_index/_mapping/_doc
{
  "properties": {
    "my_join_field": {
      "type": "join",
      "relations": {
        "question": [
          "answer",
          "comment"
        ]
      }
    }
  }
}

If you run into problems with this, please post the error messages that you're gettings and documents that cause problems.

[iamash (Yiwei)]

It works! Thank you so much