Table with multiple children

What if we added a new table publisher

Publisher

id (PK)	name
1	Oxford Press
2	Penguin Books
3	Pearson Press

and we added publisher_id as a foreign key to the Book table:

Book

isbn (PK)	title	description	publisher_id (FK)
9785811243570	Charlie and the chocolate factory	Willy Wonka’s famous chocolate factory is opening at last!	1
9788374950978	Kafka on the Shore	Kafka on the Shore is a 2002 novel by Japanese author Haruki Murakami.	2
9781471331435	1984	1984 was George Orwell’s chilling prophecy about the dystopian future.	3

We can simply define this JSON schema where the book table is still the pivot table.

[
    {
        "database": "book",
        "index": "book",
        "nodes": {
            "table": "book",
            "columns": [
                "isbn",
                "title",
                "description"
            ],
            "children": [
                {
                    "table": "author",
                    "columns": [
                        "name"
                    ]
                },
                {
                    "table": "publisher",
                    "columns": [
                        "name",
                        "id"
                    ]
                }
            ]
        }
    }
]

To get this document structure in Elasticsearch/OpenSearch

[
  {
      "isbn": "9785811243570",
      "title": "Charlie and the chocolate factory",
      "description": "Willy Wonka’s famous chocolate factory is opening at last!",
      "author": ["Roald Dahl"],
      "publisher": "Oxford Press"
  },
  {
      "isbn": "9788374950978",
      "title": "Kafka on the Shore",
      "description": "Kafka on the Shore is a 2002 novel by Japanese author Haruki Murakami",
      "author": ["Haruki Murakami", "Philip Gabriel"],
      "publisher": "Penguin Books"
  },
  {
      "isbn": "9781471331435",
      "title": "1984",
      "description": "1984 was George Orwell’s chilling prophecy about the dystopian future",
      "author": ["George Orwell"],
      "publisher": "Pearson Press"
  }
]