mongo-dump-stream | Pipe entire mongodb databases through the shell | Runtime Evironment library

Here is the idea:

Do not create backup for the whole collection but for changes (delta), and save changes that happened over time. Later you can implement restore mechanism that will walk through the delta files.

Here is how implementation looks as a concept but only for the backup mechnism that you requested:

Here is the dedicate repo for that. I also added Azure CLI script to help you quickly reproduce my idea in your Azure tenant.

General description:

1. Dependencies: azure-storage, unix-timestamp, documentdb
2. I have a time triggered function. The frequency creates blobs named by datetime stamp.
3. I store last import time in storage table.
4. To get delta I use _ts field of any document in CosmosDb.

Benefits of this approach:

1. delta-s are lighter and will be faster to import/backup
2. you can set frequency of your delta generation
3. you can see database in different states when you restore

Drawbacks:

1. you do not have one single file to restore but many