What are the two main ways of modeling relationships in MongoDB?

In MongoDB, the two main ways of modeling relationships between data are embedding and referencing.

Embedding involves nesting related data structures within a single document. This approach is beneficial when the data being modeled has a one-to-one or one-to-many relationship and when it makes sense to keep related data together for efficient access. For instance, if you have a user document that contains address information, you can embed the address directly within the user document. This reduces the need for additional queries to fetch related data and allows for atomic updates, ensuring that the user and their address are always kept in sync.

Referencing, on the other hand, involves storing a reference to a document in another document, rather than embedding the document itself. This method is useful for one-to-many relationships or when the relationship between entities is not as tightly coupled. For example, if you have a blog post and multiple comments, you might want to store each comment in its own document and reference them from the blog post. This approach prevents duplication of data and can make it easier to maintain or modify independent documents.

These methods reflect MongoDB's flexibility and adaptability to different application needs, focusing on performance and efficient data retrieval within its document-oriented model.