Data Migration from MongoDB to Azure Cosmos DB

In today's piece, I'll be exposing to you, the process that was implemented to migrate data from a MongoDB Cloud cluster to Azure CosmosDB for MongoDB. Although, before we begin to churn out the detailed steps and commands, let's expand a bit on the major elements of this write up. *What really is Azure CosmosDB? *

Curled from Microsoft Learn, Azure Cosmos DB is a fully managed NoSQL and relational database for modern app development. Azure Cosmos DB offers single-digit millisecond response times, automatic and instant scalability, along with guaranteed speed at any scale. To the best of my understanding, AZ Cosmos DB features:

• NoSQL
• MongoDB
• Apache
• Cassandra
• Apache Gremlin
• Table
• PostgreSQL

There are a couple of other resources, we can look up to gain further insights on these Database technologies.

What is MongoDB?
MongoDB is a popular open-source, NoSQL database that falls under the category of document-oriented databases. It was developed by MongoDB Inc. and is designed to handle large volumes of data, making it suitable for modern applications that require flexible and scalable storage solutions.

*Let's get started, shall we!
*

Pre-requisite:

1. MongoDB Database up and running

2. CosmosDB Database up and running
 Requirements:
3. MongoDB connection string

4. CosmosDB for MongoDB connection string
   Step 1

Set up Azure Cosmos DB: Create an Azure Cosmos DB account with the MongoDB API in your Azure subscription.
Note down the connection string for your Azure Cosmos DB account.

Step 2

Export Data from MongoDB Atlas: Export the data from your MongoDB Atlas cluster using the available tools and methods.
MongoDB provides several options for exporting data, including the mongodump command-line tool, mongoexport utility, or MongoDB Compass. mongodump command was used.



Step 3

Open powershell and run the mongodump command, mongodb will export the data from the database and store it in local machine. Command below:

mongodump --uri=<Atlas_Connection_String> --out=<Output_Directory>

Note: Remember to replace with the connection string of MongoDB Atlas cluster, and replace with the path where you want to save the exported data

Step 4

After exporting data from MongoDB to local machine, migrate the data to Azure CosmosDB for MongoDB using the mongorestore

Step 5

Prepare the backup: Ensure that you have a backup of your MongoDB data created using mongodump. The backup should be in a directory containing the BSON files and metadata.

Step 6

Run mongorestore
Two methods:
A)
mongorestore --host <hostname> --port <port> --username <username> --password <password> --authenticationDatabase <authDatabase> <backup_directory_path>

B)
mongorestore --uri <connection_uri> <backup_directory_path> -d mydb


Using method B, run the command below replacing the placeholders:

mongorestore --uri "mongodb://username:password@localhost:27017/" /path/to/backup -d mydb

Step 7

Wait for mongorestore to complete the data restoration process. The time required will be depending on the size of the data and the server’s performance.

Step 8

Verify the data by connecting to the Azure CosmosDB for MongoDB and perform queries or checks on the restored database

Step 9

Now, connect your application to use the Azure CosmosDB for MongoDB connection string
.

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