Table with single child node

Consider this example of a Book library database.

Book

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

Author

id (PK) name
1 Roald Dahl
2 Haruki Murakami
3 Philip Gabriel
4 George Orwell

BookAuthor

id (PK) book_isbn (FK) author_id (FK)
1 9785811243570 1
2 9788374950978 2
3 9788374950978 3
4 9781471331435 4

With PGSync, we can simply define this JSON schema where the book table is the pivot. A pivot table indicates the root of your document.

{
    "table": "book",
    "columns": [
        "isbn",
        "title",
        "description"
    ],
    "children": [
        {
            "table": "author",
            "columns": [
                "name"
            ]
        }
    ]
}

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"]
  },
  {
      "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"]
  },
  {
      "isbn": "9781471331435",
      "title": "1984",
      "description": "1984 was George Orwell’s chilling prophecy about the dystopian future",
      "author": ["George Orwell"]
  }
]

Behind the scenes, PGSync is generating advanced queries for you such as.

SELECT 
       JSON_BUILD_OBJECT(
          'isbn', book_1.isbn, 
          'title', book_1.title, 
          'description', book_1.description,
          'authors', anon_1.authors
       ) AS "JSON_BUILD_OBJECT_1",
       book_1.id
FROM book AS book_1
LEFT OUTER JOIN
  (SELECT 
          JSON_AGG(anon_2.anon) AS authors,
          book_author_1.book_isbn AS book_isbn
   FROM book_author AS book_author_1
   LEFT OUTER JOIN
     (SELECT 
             author_1.name AS anon,
             author_1.id AS id
      FROM author AS author_1) AS anon_2 ON anon_2.id = book_author_1.author_id
   GROUP BY book_author_1.book_isbn) AS anon_1 ON anon_1.book_isbn = book_1.isbn