DynamoDB Accelerator (or DAX) is a fully managed, clustered in-memory cache for DynamoDB
Delivers up to a 10x read performance improvement
Microsecond performance for millions of requests per second
Ideal for Read-Heavy and bursty workloads
e.g. Auction applications, gaming and retail sites during black Friday promotions
How Does it Work?
DAX is a write-through caching service - this means data is written to the cahce as well as the back end store at the same time
Allows you to point your DynamoDB API Calls at the DAX cluster
If the item you are querying is in the cache (cache hit), DAX returns the result to the application
If the item is not available (cache miss) then DAX performs an eventually consistent GetItem operation against DynamoDB
Retrieval of data from DAX reduces the read load on DynamoDB tables
May be able to reduce provisioned read capacity
What is it NOT Suitable For?
Caters for Eventually Consistent reads only - so not suitable for applications that require strongly consistent reads
write intensive applications
Applications that do not perform many read operations
Applications taht do not require microsecond response times
DAX Exam Tips
Provides in-memory caching for DynamoDB tables
Improves response times for Eventually Consistent reads only
You point your API calls at the DAX cluster instead of your table
If the item you are querying is on the cache, DAX will return it; otherwise it will perform an eventually consistent GetItem operation to your DynamoDB table
Not suitable for write-intensive applications or applications that require strongly consistent reads