Elasticsearch 6.x Join behaviour

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My concern is also similar along these lines where type allowed some sort of abstracted in cases of conflicts.

Let me elaborate on a bit from the following unanswered question of mine linked below:

Assume that we store stackoverflow data on an index. So the appropriate minimal schema would be:

Question:

  • Title
  • Content

Answers:

  • Content

In JSON, this would look something like:

{
    "mappings":{
        "question": {
            // Title, content mappings
        },
        "answer": {
            "_parent": {
                "type": "question"
            }
        }
     }
}

So this allowed me to write separate non-conflicting docs to each type:

curl -XPUT localhost:9200/so_index/question/1?routing=1 -d '{"title": "..", "content": ".."}'
curl -XPUT localhost:9200/so_index/answer/1?routing=1&parent=1 -d '{"content": ".."}'

So with the new implementation, not only I'm forced to map the "child type" to a parent (which will be removed in ES 7 of course), I've to also resolve _id 1 of parent to not conflict with _id 1 of child. So when writing a child, like shown below, it would actually overwrite the parent if the _id is same.

// Writing PARENT
curl -XPUT localhost:9200/so_index/question/1?routing=1 -d '{"title": "..", "content": "..", "join_type": { "name": "question" }}'

// Writing CHILD.
// Passing parent "type" when writing child
// Also this would overwrite the parent actually
curl -XPUT localhost:9200/so_index/question/1?routing=1 -d '{"content": "..", "join_type": { "name": "answer", "parent": 1 }}'

In such a case, is there any provision or setting to prevent this from happening? Or is it upto the client to ensure sending non-conflicting IDs in such cases?