DynamoDB Streams concept - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to enable DynamoDB Streams on a table.

DynamoDB

aws dynamodb update-table --table-name MyTable --stream-specification StreamEnabled=[1]

Drag options to blanks, or click blank then click option'

Atrue

Bon

Cenabled

Dfalse

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'enabled' or 'on' instead of true.

Using uppercase True which is invalid in CLI.

To enable DynamoDB Streams, the StreamEnabled parameter must be set to true.

2fill in blank

medium

Complete the code to specify the type of data captured by DynamoDB Streams.

DynamoDB

aws dynamodb update-table --table-name MyTable --stream-specification StreamViewType=[1]

Drag options to blanks, or click blank then click option'

ANEW_IMAGE

BNEW_AND_OLD_IMAGES

CKEYS_ONLY

DOLD_IMAGE

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing only keys or partial images instead of all attributes.

NEW_AND_OLD_IMAGES captures the entire item, both new and old images.

3fill in blank

hard

Fix the error in the code to read records from a DynamoDB Stream using AWS CLI.

DynamoDB

aws dynamodbstreams get-records --[1] iterator123

Drag options to blanks, or click blank then click option'

Ashard-iterator

BshardIterator

Csharditerator

DSharditerator

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase or incorrect casing for parameter names.

The correct parameter name is 'shard-iterator' with lowercase letters and hyphen.

4fill in blank

hard

Fill both blanks to create a DynamoDB Stream ARN for a table named 'Orders'.

DynamoDB

arn:aws:dynamodb:[1]:123456789012:table/[2]/stream/2023-01-01T00:00:00.000

Drag options to blanks, or click blank then click option'

Aus-east-1

Bus-west-2

COrders

DCustomers

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong region or table name in the ARN.

The region is 'us-west-2' and the table name is 'Orders' to form the correct ARN.

5fill in blank

hard

Fill all three blanks to filter DynamoDB Stream records for INSERT events using AWS CLI.

DynamoDB

aws dynamodbstreams get-records --shard-iterator [1] | jq '.Records[] | select(.eventName == "[2]") | .[3]'

Drag options to blanks, or click blank then click option'

Aiterator123

BINSERT

Cdynamodb

DMODIFY

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong eventName like MODIFY or DELETE.

Incorrect shard iterator value.

Accessing wrong JSON field.

The shard iterator is 'iterator123', eventName filter is 'INSERT', and the data is under 'dynamodb' key.

Practice

1. What is the primary purpose of DynamoDB Streams?

easy

A. To back up the entire DynamoDB table automatically every hour

B. To capture and record changes made to items in a DynamoDB table in real time

C. To increase the read capacity of a DynamoDB table

D. To encrypt data stored in DynamoDB tables

Solution

1. Step 1: Understand DynamoDB Streams functionality

   DynamoDB Streams capture data changes such as inserts, updates, and deletes on a table.

2. Step 2: Compare options with Streams purpose

   Only To capture and record changes made to items in a DynamoDB table in real time describes capturing changes in real time, which is the core function of Streams.

3. Final Answer:

   To capture and record changes made to items in a DynamoDB table in real time -> Option B

4. Quick Check:

   DynamoDB Streams = capture changes [OK]

Hint: Streams track table changes live, not backups or capacity [OK]

Common Mistakes:

• Confusing Streams with backups
• Thinking Streams increase capacity
• Assuming Streams encrypt data

2. Which of the following is the correct way to enable DynamoDB Streams on a table?

easy

A. Enable Auto Scaling on the table

B. Add a Global Secondary Index with StreamEnabled = true

C. Create a Lambda function and attach it to the table without enabling Streams

D. Set the StreamSpecification with StreamEnabled = true and choose a StreamViewType

Solution

1. Step 1: Recall how to enable Streams

   Streams are enabled by setting StreamSpecification with StreamEnabled true and selecting a StreamViewType.

2. Step 2: Evaluate options

   Set the StreamSpecification with StreamEnabled = true and choose a StreamViewType correctly describes enabling Streams. Other options relate to indexes, Lambda, or scaling, which do not enable Streams.

3. Final Answer:

   Set the StreamSpecification with StreamEnabled = true and choose a StreamViewType -> Option D

4. Quick Check:

   Enable Streams = StreamSpecification true + StreamViewType [OK]

Hint: Enable Streams by setting StreamSpecification true with view type [OK]

Common Mistakes:

• Confusing Streams with indexes
• Assuming Lambda enables Streams automatically
• Thinking Auto Scaling enables Streams

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

medium

A. Only the new image of the item after the change

B. Only the old image of the item before the change

C. Both the new and old images of the item

D. Only the keys of the changed item

Solution

1. Step 1: Understand StreamViewType NEW_AND_OLD_IMAGES

   This view type captures both the item image before and after the change.

2. Step 2: Match options to the view type

   Both the new and old images of the item correctly states both new and old images are included. Other options only mention one or keys.

3. Final Answer:

   Both the new and old images of the item -> Option C

4. Quick Check:

   NEW_AND_OLD_IMAGES = new + old images [OK]

Hint: NEW_AND_OLD_IMAGES means both before and after data included [OK]

Common Mistakes:

• Thinking only new or only old image is included
• Confusing keys-only view with full images
• Ignoring the StreamViewType setting

4. You have enabled DynamoDB Streams but your Lambda function is not receiving any events despite recent writes to the table. What is a possible reason?

medium

A. The Lambda function is not properly configured as an event source for the stream

B. The table has no write activity, so no stream records are generated

C. All of the above

D. The StreamViewType was set to KEYS_ONLY, but your Lambda expects full images

Solution

1. Step 1: Analyze the scenario

   Streams enabled with recent writes means records are generated, so issue is likely with Lambda setup to consume stream events.

2. Step 2: Evaluate options

   The Lambda not being configured as an event source for the stream explains no events. All of the above doesn't apply since writes occurred. No write activity contradicted by scenario. StreamViewType affects record content, not event delivery to Lambda.

3. Final Answer:

   The Lambda function is not properly configured as an event source for the stream -> Option A

4. Quick Check:

   No events despite writes = Lambda event source not mapped [OK]

Hint: Lambda must be mapped as event source to DynamoDB Stream [OK]

Common Mistakes:

• Ignoring that no writes means no stream records
• Forgetting to attach Lambda as event source
• Assuming KEYS_ONLY always sends full data

5. You want to build a system that reacts only when an item's attribute status changes in your DynamoDB table. Which StreamViewType should you choose to efficiently detect this change?

hard

A. NEW_AND_OLD_IMAGES

B. OLD_IMAGE

C. NEW_IMAGE

D. KEYS_ONLY

Solution

1. Step 1: Identify data needed to detect attribute changes

   To know if 'status' changed, you need both old and new values to compare.

2. Step 2: Match StreamViewType to requirement

   Only NEW_AND_OLD_IMAGES provides both before and after images for comparison.

3. Final Answer:

   NEW_AND_OLD_IMAGES -> Option A

4. Quick Check:

   Detect attribute change = need old + new images [OK]

Hint: Compare old and new images to detect attribute changes [OK]

Common Mistakes:

• Choosing only NEW_IMAGE or OLD_IMAGE which lacks comparison data
• Assuming KEYS_ONLY includes attribute data
• Not realizing both images are needed to detect changes