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

[
  {
      "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"
  }
]