MongoDB mongorestore and existing collection with records
mongodb, mongorestore
Solution
`mongorestore` will only drop the existing collection if you use the `--drop` argument.
If you don't use `--drop`, all documents will be inserted into the existing collection, unless a document with the same `_id` already exists. Documents with the same `_id` will be skipped, they are not merged. So `mongorestore` will never delete or modify any of the existing data by default.
Problem
I need to import (restore) a collection generated with `mongodump` into an existing database and I'd like the records to be merged into the existing collection. Does `mongorestore` merge the records in the same collection or it will drop the existing collection before restoring the records?