Flattening Native Data

You can use the Schema Tool to flatten MongoDB collections into relational tables. The following example shows how the source data is flattened.

A data source has a collection called employee with the following structure:

The employee collection would be flattened into a relational table with the following structure:

All fields are retained as separate columns in the resulting relational table. Simple types such as _id and name correspond directly to columns. In turn, subdocuments are flattened into columns using the <objectname>_<fieldname> pattern. Next, the emails array is flattened into two columns, using an extended version of the <arrayname>_<arrayindex> pattern: <objectname>_<arrayname>_<arrayindex>.