DynamoDB vs MongoDB: The 4 differences you must understand before you choose

DynamoDB vs MongoDB: The 4 differences you must understand before you choose

DynamoDB and MongoDB both offer attractive features when you’re evaluating databases for your organization. The right option for you depends on many factors, including your technology and cost requirements. Look at these key areas to determine the best selection for your business operations.

Key-Value Versus Document Storage

DynamoDB uses a key-value store, which is well-suited to simple database structures. It has a limited ability to do indexing and complex queries due to this configuration, but you don’t always need these robust capabilities when you’re developing an application. Each index adds additional cost in the form of read-write transaction billing. An external in-memory index may be the right choice cost-wise, with solutions such as ElasticCache or ElasticSearch.

MongoDB is a document store system. It offers the native ability to lookup data by any value in each “document.” You can’t do that in DynamoDB, as it’s limited to key lookups or an explicit index only. You can store, query and manage objects with ease. MongoDB also has support for some join operations and supports graph queries in aggregations. MongoDB also maintains as much of its data in memory as possible, acting as a kind of in-memory database. This means you often can avoid having to add a database caching layer to your design. MongoDB gives you capabilities needed for more complex technical requirements.

Installation And Setup

DynamoDB offers a streamlined and simple installation experience. It’s a proprietary NoSQL database that only runs on Amazon Web Services, so you don’t have a lot of unknown variables to deal with during this process. AWS has a user-friendly wizard that walks you through the process so there’s no confusion.

MongoDB requires more deployment resources, as it’s an open-source database that’s compatible with a wide range of environments. The flexibility is excellent if you don’t want to use AWS as part of your infrastructure or you prefer to avoid a potential vendor lock-in in the future. You need to tailor the installation process to your unique configuration, and if you run into problems, you need IT specialists familiar with your environment and MongoDB. You’re also responsible for setting up individual database replica servers, as well as creating and managing the shards for the data split. Keep in mind that poorly considered sharding decisions can cause slow performance as you add more data to your MongoDB database.

Fixed and Variable Costs

DynamoDB starts out as the less-expensive option overall, as it’s a hosted database that’s leveraging AWS. Your initial outlay is low when you don’t have to worry about routine maintenance technicians, extra deployment staff or physical servers. However, if you want more functionality out of this system, you need to pay for database caching and possibly an in-memory index such as AWS ElastiCache or AWS ElasticSearch. Get estimates on how much that will cost when you’re estimating how much you’re going to pay for DynamoDB. Your scaling costs will usually increase relatively gradually with your usage since you don’t need to pay for additional servers to get greater capacity.

MongoDB has a higher initial cost with its complex installation and hardware requirements. You’re also responsible for day-to-day maintenance, unless you use one of the hosted options available from MongoDB Atlas, mLab, or Compose. However, you have access to advanced functionality out of the box, rather than adding it in after the installation. The variable costs could be lower over time when you have access to a more robust toolset instead of trying to cut down functionality to fit the database features you have available.

If you do host MongoDB yourself, you also don’t have a monthly payment to use the database. However, MongoDB costs grow like a step function. You’ll see large leaps as you go up in data size because you will have to add new database shards, each of which usually contains several replica servers.

The hosted MongoDB options sometimes include a free tier for developer use and may help control maintenance costs as well, so hosted MongoDB options may be the right choice when you’re just getting started with this database.

Performance Adjustments and Pricing

Scaling DynamoDB is almost as easy as getting it installed. AWS offers a flexible infrastructure that can adapt to your business needs as you grow. However, the price to scale can be significant, depending on the resources you need for your databases.

You need to buy additional servers and other equipment when you want to scale MongoDB, but you have more control over the pricing since you can shop around with different vendors. Since you control the infrastructure that the database uses, you can tweak the performance to optimize your databases to adapt to your business needs.


DynamoDB and MongoDB are both solid database solutions that can benefit your software development. DynamoDB starts out cheaper, but may require you to build more code if your requirements are not simple. MongoDB gives you more features, but also costs more to start using in production. Carefully consider the pros and cons of each option, including the potential long-term costs, before you add them to your project.

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