DynamoDB Streams overview in AWS - Mini Project: Build & Apply

DynamoDB Streams overview

📖 Scenario: You are working on a cloud project where you need to track changes in a DynamoDB table. DynamoDB Streams help capture these changes in real-time.

🎯 Goal: Create a DynamoDB table with streams enabled, configure the stream view type, and verify the stream settings.

📋 What You'll Learn

Create a DynamoDB table named Orders with a primary key OrderId of type string.

Enable DynamoDB Streams on the Orders table with the stream view type set to NEW_AND_OLD_IMAGES.

Write an AWS CLI command or AWS SDK code snippet to describe the table and confirm streams are enabled.

💡 Why This Matters

🌍 Real World

DynamoDB Streams are used to capture and react to changes in your database in real-time, useful for auditing, replication, or triggering workflows.

💼 Career

Understanding DynamoDB Streams is important for cloud engineers and developers working with AWS to build event-driven and reactive applications.

1

Create the DynamoDB table

Create a DynamoDB table named Orders with a primary key called OrderId of type string.

AWS

# Your AWS CLI command or AWS SDK code to create the table goes here

Hint

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

2

Enable DynamoDB Streams

Update the Orders table to enable DynamoDB Streams with the stream view type set to NEW_AND_OLD_IMAGES.

AWS

aws dynamodb create-table --table-name Orders --attribute-definitions AttributeName=OrderId,AttributeType=S --key-schema AttributeName=OrderId,KeyType=HASH --provisioned-throughput ReadCapacityUnits=5,WriteCapacityUnits=5
# Your AWS CLI command to enable streams goes here

Hint

Use the AWS CLI update-table command with the --stream-specification option.

3

Describe the table to verify streams

Write an AWS CLI command to describe the Orders table and confirm that DynamoDB Streams are enabled with the correct stream view type.

AWS

aws dynamodb create-table --table-name Orders --attribute-definitions AttributeName=OrderId,AttributeType=S --key-schema AttributeName=OrderId,KeyType=HASH --provisioned-throughput ReadCapacityUnits=5,WriteCapacityUnits=5
aws dynamodb update-table --table-name Orders --stream-specification StreamEnabled=true,StreamViewType=NEW_AND_OLD_IMAGES
# Your AWS CLI command to describe the table goes here

Hint

Use the AWS CLI describe-table command to check the table details.

4

Check the stream settings in the output

Verify that the output of the describe-table command includes StreamEnabled set to true and StreamViewType set to NEW_AND_OLD_IMAGES.

AWS

aws dynamodb create-table --table-name Orders --attribute-definitions AttributeName=OrderId,AttributeType=S --key-schema AttributeName=OrderId,KeyType=HASH --provisioned-throughput ReadCapacityUnits=5,WriteCapacityUnits=5
aws dynamodb update-table --table-name Orders --stream-specification StreamEnabled=true,StreamViewType=NEW_AND_OLD_IMAGES
aws dynamodb describe-table --table-name Orders
# Your code or comment to confirm stream settings goes here

Hint

Look for the stream settings in the table description output.

Practice

1. What is the main purpose of DynamoDB Streams?

easy

A. To store backups of DynamoDB tables permanently

B. To encrypt data stored in DynamoDB tables

C. To increase the read capacity of a DynamoDB table

D. To track and react to data changes in real time

Solution

1. Step 1: Understand DynamoDB Streams function

   DynamoDB Streams capture data changes like inserts, updates, and deletes in real time.

2. Step 2: Compare options with Streams purpose

   Only To track and react to data changes in real time correctly describes tracking and reacting to data changes. Other options describe unrelated features.

3. Final Answer:

   To track and react to data changes in real time -> Option D

4. Quick Check:

   DynamoDB Streams = Track data changes [OK]

Hint: Streams capture table changes instantly for reaction [OK]

Common Mistakes:

• Confusing Streams with backup or encryption features
• Thinking Streams increase read capacity
• Assuming Streams store data permanently

2. Which setting must be enabled to start using DynamoDB Streams on a table?

easy

A. EncryptionEnabled set to true

B. BackupEnabled set to true

C. StreamEnabled set to true

D. AutoScalingEnabled set to true

Solution

1. Step 1: Identify the configuration for enabling Streams

   To use DynamoDB Streams, the table must have StreamEnabled set to true.

2. Step 2: Eliminate unrelated settings

   BackupEnabled, EncryptionEnabled, and AutoScalingEnabled do not enable Streams.

3. Final Answer:

   StreamEnabled set to true -> Option C

4. Quick Check:

   Enable Streams = StreamEnabled true [OK]

Hint: Enable Streams by setting StreamEnabled true [OK]

Common Mistakes:

• Confusing Streams with backups or encryption
• Assuming AutoScaling enables Streams
• Forgetting to enable Streams explicitly

3. Given a DynamoDB Stream with StreamViewType set to NEW_AND_OLD_IMAGES, what data will the stream record for each change?

medium

A. Only the new item image after the change

B. Both the new and old item images

C. Only the keys of the changed items

D. Only the old item image before the change

Solution

1. Step 1: Understand StreamViewType NEW_AND_OLD_IMAGES meaning

   This setting records both the item before and after the change.

2. Step 2: Compare options with StreamViewType behavior

   Only Both the new and old item images matches the behavior of capturing both new and old images.

3. Final Answer:

   Both the new and old item images -> Option B

4. Quick Check:

   NEW_AND_OLD_IMAGES = new + old data [OK]

Hint: NEW_AND_OLD_IMAGES means capture before and after data [OK]

Common Mistakes:

• Choosing only new or only old images
• Confusing keys only with full images
• Not knowing StreamViewType options

4. A developer enabled DynamoDB Streams but does not see any stream records after table updates. What is the most likely cause?

medium

A. StreamEnabled is false on the table

B. StreamViewType is set to KEYS_ONLY

C. Stream retention period is set to 7 days

D. The table has no primary key defined

Solution

1. Step 1: Check if Streams are enabled

   If StreamEnabled is false, no stream records are generated regardless of updates.

2. Step 2: Evaluate other options

   KEYS_ONLY still produces records; retention period (24-168 hours) does not prevent seeing recent records; tables require primary keys but that doesn't stop streams if enabled.

3. Final Answer:

   StreamEnabled is false on the table -> Option A

4. Quick Check:

   No records = Streams not enabled [OK]

Hint: Streams must be enabled to see records [OK]

Common Mistakes:

• Assuming KEYS_ONLY disables records
• Thinking retention period prevents seeing records
• Ignoring StreamEnabled setting

5. You want to trigger a Lambda function whenever an item is updated in your DynamoDB table to process both the old and new item images. Which DynamoDB Streams configuration and setup is required?

hard

A. Enable Streams with StreamViewType NEW_AND_OLD_IMAGES and configure Lambda trigger on the stream

B. Enable Streams with StreamViewType KEYS_ONLY and configure Lambda trigger on the table

C. Enable Streams with StreamViewType NEW_IMAGE and configure Lambda trigger on the stream

D. Enable Streams with StreamViewType OLD_IMAGE and configure Lambda trigger on the table

Solution

1. Step 1: Choose StreamViewType for updates

   To capture both before and after update data, use NEW_AND_OLD_IMAGES.

2. Step 2: Configure Lambda trigger on the DynamoDB Stream

   Lambda triggers must be set on the stream, not directly on the table.

3. Final Answer:

   Enable Streams with StreamViewType NEW_AND_OLD_IMAGES and configure Lambda trigger on the stream -> Option A

4. Quick Check:

   Lambda trigger on stream with NEW_AND_OLD_IMAGES [OK]

Hint: Use NEW_AND_OLD_IMAGES and trigger Lambda on stream [OK]

Common Mistakes:

• Triggering Lambda directly on table instead of stream
• Choosing KEYS_ONLY or OLD_IMAGE for update data
• Not enabling Streams before Lambda trigger