After seeing how to work with documents and how to work with relational tables, this section explains how to combine the two and work with both at the same time.
It can be beneficial to use documents for very specific tasks inside an application and rely on relational tables for other tasks. Or a very simple document only application can outgrow the document model and incrementally integrate or move to a more powerful relational database. This way the advantages of both documents and relational tables can be combined. SQL tables contribute strictly typed value semantics, predictable and optimized storage. Documents contribute type flexibility, schema flexibility and non-scalar types.