Question 598 - SAA-C03 discussion

The most cost-effective DynamoDB table configuration for the web application is to configure DynamoDB in on-demand mode by using the DynamoDB Standard table class. This configuration will allow the company to scale in response to application traffic and pay only for the read and write requests that the application performs on the table.

On-demand mode is a flexible billing option that can handle thousands of requests per second without capacity planning. On-demand mode automatically adjusts the table's capacity based on the incoming traffic, and charges only for the read and write requests that are actually performed. On-demand mode is suitable for applications with unpredictable or variable workloads, or applications that prefer the ease of paying for only what they use1.

The DynamoDB Standard table class is the default and recommended table class for most workloads. The DynamoDB Standard table class offers lower throughput costs than the DynamoDB Standard-Infrequent Access (DynamoDB Standard-IA) table class, and is more cost-effective for tables where throughput is the dominant cost. The DynamoDB Standard table class also offers the same performance, durability, and availability as the DynamoDB Standard-IA table class2.

The other options are not correct because they are either not cost-effective or not suitable for the use case. Configuring DynamoDB with provisioned read and write by using the DynamoDB Standard table class, and setting DynamoDB auto scaling to a maximum defined capacity is not correct because this configuration requires manual estimation and management of the table's capacity, which adds complexity and cost to the solution. Provisioned mode is a billing option that requires users to specify the amount of read and write capacity units for their tables, and charges for the reserved capacity regardless of usage. Provisioned mode is suitable for applications with predictable or stable workloads, or applications that require finer-grained control over their capacity settings1. Configuring DynamoDB with provisioned read and write by using the DynamoDB Standard-Infrequent Access (DynamoDB Standard-IA) table class, and setting DynamoDB auto scaling to a maximum defined capacity is not correct because this configuration is not cost-effective for tables with moderate to high throughput. The DynamoDB Standard-IA table class offers lower storage costs than the DynamoDB Standard table class, but higher throughput costs. The DynamoDB Standard-IA table class is optimized for tables where storage is the dominant cost, such as tables that store infrequently accessed data2. Configuring DynamoDB in on-demand mode by using the DynamoDB Standard-Infrequent Access (DynamoDB Standard-IA) table class is not correct because this configuration is not cost-effective for tables with moderate to high throughput. As mentioned above, the DynamoDB Standard-IA table class has higher throughput costs than the DynamoDB Standard table class, which can offset the savings from lower storage costs.

Table classes - Amazon DynamoDB

Read/write capacity mode - Amazon DynamoDB