Amazon DynamoDB Accelerator (DAX) is a fully managed, in-memory caching service designed to accelerate read performance for Amazon DynamoDB applications. It provides fast in-memory performance for read-heavy and bursty workloads, reducing the latency of DynamoDB operations from milliseconds to microseconds.
DAX acts as a cache layer for DynamoDB, enabling faster access to frequently-read data, offloading the load from the DynamoDB table, and reducing response times for repeated queries. It integrates seamlessly with DynamoDB and is designed to be used with minimal changes to your existing DynamoDB-based applications.
Key Features of DynamoDB Accelerator (DAX)
Microsecond Read Latency:
DAX can provide microsecond read latency for data stored in DynamoDB. It accelerates reads from milliseconds (typical of DynamoDB) to microseconds, making it suitable for applications that require high-performance reads, such as gaming, ad tech, or real-time analytics.
Fully Managed:
DAX is fully managed by AWS, meaning it handles the underlying infrastructure, scaling, patching, and availability. You don’t need to worry about provisioning or maintaining the hardware for caching.
Easy Integration with DynamoDB:
DAX is designed to integrate seamlessly with DynamoDB. You can simply add DAX to your DynamoDB-based application without significant code changes. Your application uses the DynamoDB API for read requests, and DAX automatically handles caching.
Write-Through Caching:
DAX uses write-through caching, meaning when data is written to DynamoDB, it is also automatically written to the DAX cache. This ensures that the cache remains consistent with the underlying DynamoDB table.
Automatic Scaling:
DAX automatically scales based on your application’s usage. You can start with a small cache cluster and scale up as needed to meet higher throughput demands.
Data Persistence:
While DAX caches data in-memory, it is not a replacement for DynamoDB. It works as a cache layer for read-heavy workloads, and the data is still persisted in DynamoDB.
Clustered Architecture:
DAX operates in a clustered environment for high availability and fault tolerance. You can create a cluster of DAX nodes to improve both performance and availability.
Highly Available and Fault-Tolerant:
DAX clusters are deployed across multiple Availability Zones (AZs) to ensure high availability. If one node or AZ fails, other nodes in the cluster continue serving requests.
Security Integration:
DAX integrates with AWS Identity and Access Management (IAM) for access control and Amazon Virtual Private Cloud (VPC) for network isolation. You can also enable encryption at rest and in transit to protect sensitive data.
How DynamoDB DAX Works
Cache Population:
DAX caches the most frequently accessed data from DynamoDB in memory. When a read request is made to DynamoDB, DAX first checks its cache to see if the data is already available. If the data is in the cache (a cache hit), it returns the result quickly from memory. If the data is not in the cache (a cache miss), it retrieves it from DynamoDB and stores it in the cache for future requests.
Read Requests:
Applications interact with DAX in the same way they interact with DynamoDB. When a request is made, DAX decides whether to serve it from its in-memory cache or forward the request to DynamoDB.
Cache Management:
DAX automatically manages the cache and decides what data should be kept in memory based on the data’s usage patterns. Data is evicted from the cache when memory is needed for new or more frequently accessed data.
Write-Through Cache:
When an application writes data to DynamoDB, the write is immediately reflected in the DAX cache. This ensures that the cache remains consistent with DynamoDB, providing fast reads even after updates.