1. What is DynamoDB Provisioned Capacity?

DynamoDB Provisioned Capacity allows you to specify the throughput capacity (read and write) required for your application. RCU (Read Capacity Units) and WCU (Write Capacity Units) determine how much data you can read and write per second.

2. How Does the Calculator Work?

The calculator uses the DynamoDB capacity formula:

Where:

• \( \text{Reads/Writes per sec} \) — Number of read or write operations per second
• \( \text{Item Size KB} \) — Average size of items in kilobytes
• \( 4 \) — Base unit size (4KB per RCU/WCU)

Explanation: Each RCU provides one strongly consistent read per second for items up to 4KB in size. Each WCU provides one write per second for items up to 1KB in size (hence the division by 4 for KB-sized items).

3. Importance of Capacity Planning

Details: Proper capacity planning ensures your DynamoDB tables can handle the expected workload without throttling, while also optimizing costs by not over-provisioning capacity.

4. Using the Calculator

Tips: Select operation type (read/write), enter the expected operations per second, and the average item size in KB. The calculator will determine the required RCU or WCU units.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between RCU and WCU?
A: RCU (Read Capacity Unit) handles read operations, while WCU (Write Capacity Unit) handles write operations. Each has different capacity calculations.

Q2: How does item size affect capacity requirements?
A: Larger items require more capacity units. For reads, items larger than 4KB require additional RCUs. For writes, items larger than 1KB require additional WCUs.

Q3: What happens if I exceed provisioned capacity?
A: DynamoDB will throttle requests that exceed provisioned capacity, potentially causing application errors or delays.

Q4: Can I use auto-scaling with provisioned capacity?
A: Yes, DynamoDB offers auto-scaling to automatically adjust capacity based on actual usage patterns.

Q5: How often should I review my capacity settings?
A: Regularly monitor your usage and adjust capacity as your application's needs change, especially during peak periods or growth phases.