When comparing Redis vs DynamoDB, the Slant community recommends Redis for most people. In the question“What are the best NoSQL databases for web applications?” Redis is ranked 2nd while DynamoDB is ranked 7th.
Ranked in these QuestionsQuestion Ranking
Pro Redis is written in ANSI C and therefore doesn't have a VM
Pro Good support
Redis has great docs, an active mailing list, and a github community.
Pro Redis uses the BSD license
This means that it is able to be used in a commercial product if one wants.
Pro There are numerous client libraries and frameworks to make redis more powerful
For Node.JS for example you can get something similar to what Parse.com was offering by using Node ORM.
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
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.
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.