How to Copy a Collection of Documents to Another Database with mongosh

If you need to copy a collection of documents from one Mongo collection to another, you can use the mongodump and mongorestore. But if the source database is in the same instance as the target, then you may be able to take a shortcut with mongosh.

Here is the script to use:

db.<source collection>.find().forEach(function(d){ db.getSiblingDB('<dest db>')['<dest collection>'].insert(d); });

For example, if you are copying all documents from current databases cars collection to a database called another-db’s collection vehicles:

db.cars.find().forEach(function(d){ db.getSiblingDB('another-db')['vehicles'].insert(d); });

Of course, you can add filters to the find method if you want to copy only subset of documents.