You are the data modeler responsible for building a logical data model of an existing NoSQL MongoDB database. Your plan is to reverse engineer the existing database into a physical data model using your data modeling tool, and then translate this physical data model into a logical data model. Many of the MongoDB concepts translate nicely into traditional data modeling components, but the concept of an array does not seem to fit.
For example, there is a one-to-many relationship between Order and Order Line which can be implemented in one of three ways:
1) The physical data model can resemble in structure the logical data model and be implemented as a one-to-many relationship:
2) The Order entity can be collapsed down (embedded) into the Order Line child:
3) The Order Line attributes can be rolled up into the Order entity. The challenge with this repeating attributes technique is that we need to determine the maximum number of lines an order can contains (in this example, three order lines):
An array concept in MongoDB is most similar to this third model (rolling up), except that there is no limit to the number of children the parent can have. An Order can have three lines, but can also have three hundred lines.
How would you show this array concept on the data model diagram?