Hi there!
The aggregation framework stage $out does not show information about what is the percentage already done. In large collections, it would really help to know this info.
This is an operation that blocks the shell until it is finished, so we can use this to show (in the shell) that percentage. Something similar to what the createIndex does.
I think the shell is a good place due to the log is showing the inserts, and we would not be able to see these messages among many inserts.
Thank you very much!