Reserved capacity in DynamoDB

Introduction

Reserved capacity helps you save money by paying upfront for a set amount of database capacity instead of paying for it as you go.

You know your app will need a steady amount of database power for a long time.

You want to reduce costs for your database usage by committing ahead.

You want to avoid surprises from sudden spikes in database charges.

You have a predictable workload and want to plan your budget better.

Syntax

DynamoDB

Reserved capacity is purchased through AWS Management Console or AWS CLI, not by a direct query.
You specify:
- Capacity units (read/write)
- Duration (usually 1 or 3 years)
- Payment option (all upfront, partial, or monthly)

Reserved capacity is not a query but a billing option you set up before using the database.

It applies to your whole account.

Examples

This AWS CLI command buys 5 units of reserved capacity for DynamoDB.

DynamoDB

aws dynamodb purchase-reserved-capacity-offering --reserved-capacity-offering-id <offering-id> --reserved-capacity-quantity 5

This is how you buy reserved capacity using the AWS web interface.

DynamoDB

In AWS Console, go to DynamoDB > Reserved Capacity > Purchase
Select capacity units and payment plan
Confirm purchase

Sample Program

This command purchases 10 reserved capacity units using the specified offering ID.

DynamoDB

-- Reserved capacity is not created by SQL or query language.
-- Instead, you buy it via AWS CLI or Console.
-- Example CLI command:
aws dynamodb purchase-reserved-capacity-offering --reserved-capacity-offering-id abc123 --reserved-capacity-quantity 10

Important Notes

Reserved capacity reduces your hourly cost but requires upfront commitment.

You cannot query reserved capacity like data; it is a billing setting.

Make sure to estimate your needs carefully before purchasing.

Summary

Reserved capacity saves money by pre-paying for database power.

It is bought through AWS Console or CLI, not by database queries.

Best for steady, predictable workloads to control costs.