MongoDB Connector > Mappings and Mapping Tasks with MongoDB > Reading hierarchical data in mappings
  

Reading hierarchical data in mappings

To preserve the hierarchical structure when you read data from MongoDB and write data to relational targets, you must use a Hierarchy Parser transformation.
The Hierarchy Parser transformation processes JSON input from the source transformation and provides relational output to the target transformation. The Hierarchy Parser transformation converts hierarchical input based on the sample schema of the MongoDB table that you associate with the transformation and the way that you map the data.