When comparing DynamoDB vs CouchDB, the Slant community recommends CouchDB for most people. In the question“What are the best NoSQL databases for web applications?” CouchDB is ranked 4th while DynamoDB is ranked 12th. The most important reason people chose CouchDB is:
CouchDB works very well even when the network is physically partitioned
Specs
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Pros
Pro Free tier
DynamoDB offers a free tier which allows up to 40 million database operations a month for free.
Pro Trigger tasks (AWS Lambda) on write
When a new record is written, it can trigger one or many AWS Lambda functions. With Lambda functions in Java, JavaScript, and Python and the other con of "Easy integration with other Amazon services", Lambda functions may be all you need to process the events. This is particularly useful for creating projections (often as other DynamoDB tables) and other read models in a CQRS pattern.
Pro High uptime
Data hosted on DynamoDB is automatically replicated across multiple AWS availability zones, this way the data is protected from any malfunction that may cause loss and it also ensures high uptime.
Pro Easy integration with other Amazon services
Since it's part of AWS, like with other services that Amazon provides, it's very easy to integrate DynamoDB with any other AWS service that you may be using.
Pro Works well between physical network partitions
CouchDB works very well even when the network is physically partitioned
Pro Available
CouchDB is considered an available DMS according to the ACP theory of database management. As such it allows every client to always read and write
Pro Useful for applications where versioning is important
CouchDB is mostly used in applications where a large amount of data needs to be accumulated and where data only changes rarely.
Pro Changes API
You can use the RESTful API to listen for changes in your database, which is something most databases can't do. It makes it really easy for clients to keep their view of data up-to-date.
Pro RESTful API
Since everything is stored as a JSON document and served over HTTP, it's perfectly suited for communicating with client-side javascript, with or without middleware.
Cons
Con No specific features for Event Sourcing
DynamoDB is just a general purpose NoSQL database; hence, there are no features specific to the domain of Event Sourcing, such as event ordering or projections. As a developer, you will need to decide how to implement these.
Con Poor documentation
In true AWS fashion, the documentation for DynamoDB is not top notch. While the learning curve is generally very soft and it's not hard to learn, you need to have at least some experience with cloud and database management to be able to start using DynamoDB and understand the documentation.
Con Can only achieve consistency through replication and verification
Since CouchDB is considered an AP (Available, Partition-Tolerant database management system), it is not really consistent (not all clients can have the same view of the data consistently) and the only way to achieve some "eventual consistency" is through replication and verification of data.
Con Uncertain future
After a very promising start, development began to drag after major supporters like Canonical, Selenium and CouchOne either shut down or moved to other tools. Development has begun to pick up again.