Why automatic expiration manages data lifecycle in DynamoDB - See It in Action

Manage Data Lifecycle with Automatic Expiration in DynamoDB

📖 Scenario: You are managing a DynamoDB table that stores user session data. To keep the table clean and efficient, you want to automatically remove old sessions after a certain time.

🎯 Goal: Build a DynamoDB table setup that uses automatic expiration to manage the lifecycle of session data by removing expired items automatically.

📋 What You'll Learn

Create a DynamoDB table named Sessions with a primary key SessionId (string).

Add an attribute ExpirationTime (number) to store the UNIX timestamp when the session expires.

Enable Time To Live (TTL) on the ExpirationTime attribute to automatically delete expired items.

Insert sample session items with specific expiration times.

💡 Why This Matters

🌍 Real World

Automatic expiration helps keep databases clean by removing old or unused data without manual intervention, saving storage and improving performance.

💼 Career

Understanding TTL in DynamoDB is important for roles involving cloud database management, backend development, and data lifecycle automation.

1

Create the DynamoDB table with primary key

Create a DynamoDB table named Sessions with a primary key called SessionId of type string.

DynamoDB

# Your code here to create the Sessions table with SessionId as primary key

Need a hint?

Use the AWS CLI create-table command with --attribute-definitions and --key-schema for the primary key.

2

Add the ExpirationTime attribute to items

Add an attribute called ExpirationTime of type number to your session items. This will store the UNIX timestamp when the session should expire.

DynamoDB

aws dynamodb create-table \
    --table-name Sessions \
    --attribute-definitions AttributeName=SessionId,AttributeType=S \
    --key-schema AttributeName=SessionId,KeyType=HASH \
    --provisioned-throughput ReadCapacityUnits=5,WriteCapacityUnits=5
# Your code here to add ExpirationTime attribute to session items

Need a hint?

Use put-item to add items with SessionId and ExpirationTime attributes.

3

Enable TTL on the ExpirationTime attribute

Enable Time To Live (TTL) on the Sessions table using the attribute ExpirationTime so that DynamoDB automatically deletes expired items.

DynamoDB

aws dynamodb create-table \
    --table-name Sessions \
    --attribute-definitions AttributeName=SessionId,AttributeType=S \
    --key-schema AttributeName=SessionId,KeyType=HASH \
    --provisioned-throughput ReadCapacityUnits=5,WriteCapacityUnits=5

aws dynamodb put-item \
    --table-name Sessions \
    --item '{"SessionId": {"S": "session1"}, "ExpirationTime": {"N": "1700000000"}}'

aws dynamodb put-item \
    --table-name Sessions \
    --item '{"SessionId": {"S": "session2"}, "ExpirationTime": {"N": "1700003600"}}'
# Your code here to enable TTL on ExpirationTime attribute

Need a hint?

Use the AWS CLI update-time-to-live command to enable TTL on the ExpirationTime attribute.

4

Insert a new session with expiration time

Insert a new session item with SessionId set to session3 and ExpirationTime set to UNIX timestamp 1700007200.

DynamoDB

aws dynamodb create-table \
    --table-name Sessions \
    --attribute-definitions AttributeName=SessionId,AttributeType=S \
    --key-schema AttributeName=SessionId,KeyType=HASH \
    --provisioned-throughput ReadCapacityUnits=5,WriteCapacityUnits=5

aws dynamodb put-item \
    --table-name Sessions \
    --item '{"SessionId": {"S": "session1"}, "ExpirationTime": {"N": "1700000000"}}'

aws dynamodb put-item \
    --table-name Sessions \
    --item '{"SessionId": {"S": "session2"}, "ExpirationTime": {"N": "1700003600"}}'

aws dynamodb update-time-to-live \
    --table-name Sessions \
    --time-to-live-specification Enabled=true,AttributeName=ExpirationTime
# Your code here to insert session3 with ExpirationTime 1700007200

Need a hint?

Use put-item to add the new session with the specified expiration time.