Exam AWS Certified Solutions Architect - Professional SAP-C02 topic 1 question 327 discussion

C - DynamoDB is for structured, semi-structured and unstructured data. So it can also hold the product data. Indeed many e-commerce shops use DynamoDB to save the product catalogue. There is nothing in the questin that would exclude DynamoDB for the product data. C has caching with DAX so it definitely has a higher performance than D which does not have caching and even no read replica in the same region.

Structured Data = RDS

Memcached isnt supported in elasticache global tables: https://aws.amazon.com/elasticache/faqs/#topic-7 "Global Datastore is supported on ElastiCache version 7.2 for Valkey and ElastiCache version 5.0.6 onward for Redis OSS." https://docs.aws.amazon.com/AmazonElastiCache/latest/dg/Redis-Global-Datastore.html

"Structured data" should be a giveaway.....no matter how fast DynamoDB is, it's still a key-value storage. Yeah a simple JSON can be stored effectively, but actual data will never be as fast as a proper RDS.

DynamoDB with DAX is specifically designed for high-performance use cases, making it the optimal choice when performance is the key requirement.

Decoupling: Storing product data and session data in separate DynamoDB tables fully decouples the two data types. High performance: DynamoDB is highly performant for both structured and temporary data. DAX provides microsecond latency caching for DynamoDB queries. Global replication: Global Tables provide multi-Region, active-active replication, meeting disaster recovery (DR) needs without complex setup. Scalability: DynamoDB can scale automatically with minimal operational overhead.

Option C is suboptimal because using DynamoDB for structured product data may be less efficient and more costly than RDS, especially for complex relationships and large datasets. It also adds unnecessary complexity and reduces query flexibility compared to relational databases. In contrast, option D offers a better solution by using RDS for structured product data and DynamoDB for session data, providing an optimal balance of performance, cost-effectiveness, and appropriate technology choices for different data types, while meeting the requirements for decoupling and cross-region replication. Thus, the correct answer is D.

DynamoDB provide microseconds to single digit latency read/write also DynamoDB support structured data just fine

Option C, provide highest performance. Creating two Amazon DynamoDB global tables—one for product data and another for user session data—while utilizing DynamoDB Accelerator (DAX) for caching. This setup allows for low-latency access and high throughput, making it ideal for applications with demanding performance requirements. Additionally, DynamoDB's global tables offer built-in replication across regions, ensuring disaster recovery capabilities without compromising performance.

This https://docs.aws.amazon.com/whitepapers/latest/big-data-analytics-options/amazon-dynamodb.html mentions indeed "DynamoDB stores structured data in tables". Based on the question, I would go with C

Option C (using two DynamoDB global tables with DAX caching) provides the highest performance by leveraging the scalability, low latency, and caching capabilities of DynamoDB, while also meeting the requirements of data separation and replication for disaster recovery. The other options have limitations or drawbacks: Option A: While separate schemas in an Amazon RDS DB instance can separate the data, it lacks the performance and scalability of DynamoDB. Setting up replication across Regions for RDS is also more complex than using DynamoDB global tables. Option B: This option separates the data and provides replication, but using Amazon ElastiCache for Memcached for user session data may not match DynamoDB's performance for structured data. Managing two different data stores (RDS and ElastiCache) can also add complexity. Option D: While separating the data and providing replication, using RDS for the product data may not be as performant as DynamoDB for structured data, especially with high-traffic workloads.

D is correct Decouples the product data from the user session data by using separate storage mechanisms (RDS and DynamoDB). Provides replication in another AWS Region for disaster recovery, which is necessary. Dynamodb provides low latency reads and writes making it suitable for this application and high traffic application And DynamoDB has built-in features to automatically handle the replication of the user session data across regions.

Answer is D, Elasticache Global data Store only supports Redis

I think D. ElastiCache for Memcached and DAX are good for read-heavy so they can improve performance, but not a good choice for read and write, and also Memcached – no replication

Querying structured data on DynamoDB does not provide as good performance as RDS

C - To meet Disaster Recovery requirements & get high performance with DAX

D. Structure Data so Amazon RDS and Amazon DynamoDB is well-suited for handling session data and can provide low-latency access. Not C because Dynamo is not for structured data