1:1 embedded relationship:

M:1 linked relationship(one_direction):

child uses belongs_to

parent uses has_many

1:M embedded relationship:

M:1 embedded relationship:

*annotated link

*"1" side has a primary key and typically has no reference to the child within the document

*"M" side will typically host the foreign key

1：1 Linked relationship - has_one:

child belongs_to

parents has_one

M:M Linked Relationship

has_and_belongs_to_many

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