Would the following be the right way to populate the InstanceUsage table:

1. For a row in InstanceUsage, take the request_id and get all the entries in Rawdata for that request_id.
2. Populate the usage fields in that InstanceUsage row using the information in the image_meta dictionary of the latest entry in the RawData for that request_id.

This assumes that the latest entry in the RawData table for a request-id would have caused the final update on a particular row in the InstanceUsage table with that request-id.