How to: ElastiCache Gotchas and Limitations
- Since in some cases changing the cache clusters may have some restrictions,
  like for
  [scaling](http://docs.aws.amazon.com/AmazonElastiCache/latest/UserGuide/Scaling.html)
  purposes, it may become a problem if they were launched using CloudFormation
  in a stack that also contains other resources and you really need to change
  the cache. In order to avoid getting your CloudFormation stacks in a
  non-updateable state, it is recommended to launch ElastiCache clusters (just
  like any other resource with similar constraints) in dedicated stacks which
  can be replaced entirely with new stacks having the desired configuration.

DynamoDB
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