Which solution will meet these requirements MOST cost-effectively?
Use provisioned mode and DynamoDB Standard-Infrequent Access (DynamoDB Standard-IA). Reserve capacity for the forecasted workload.
Use provisioned mode. Specify the read capacity units (RCUs) and write capacity units (WCUs).
Use on-demand mode. Set the read capacity units (RCUs) and write capacity units (WCUs) high enough to accommodate changes in the workload.
Use on-demand mode. Specify the read capacity units (RCUs) and write capacity units (WCUs) with reserved capacity.
Explanations:
While using provisioned mode with Standard-IA could save costs for infrequently accessed data, the use of reserved capacity requires accurate forecasting of usage. If the workload is constant and predictable, this option may not fully optimize costs as compared to using provisioned capacity directly without relying on IA storage.
Provisioned mode allows the company to specify RCUs and WCUs according to the constant and predictable workload. This option is the most cost-effective because it enables the company to pay for exactly what it needs, without the unpredictability of on-demand costs.
On-demand mode is generally more expensive for constant and predictable workloads due to its pricing structure, which is based on actual usage. This option could lead to exceeding budget forecasts if usage is not closely monitored.
On-demand mode does not require setting RCUs and WCUs, as it automatically scales based on the workload. Specifying RCUs and WCUs with reserved capacity in on-demand mode is not applicable, making this option unnecessary and potentially more costly.
I outline that the answer is:
Use provisioned mode. Specify the read capacity units (RCUs) and write capacity units (WCUs).