DynamoDB Streams overview in AWS - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

How does DynamoDB Streams capture data changes?

Which statement best describes how DynamoDB Streams captures changes in a DynamoDB table?

A It sends notifications to an email address for each data change.

B It captures only the final state of the table once every hour.

C It stores a backup of the entire table every time a change happens.

D It records every data modification as a stream record in the order they occurred.

💡 Hint

Think about how a stream works as a sequence of events.

DynamoDB Streams records each data modification as a stream record in the order they occur, allowing applications to process changes sequentially.

❓ service_behavior

intermediate

What happens when you enable DynamoDB Streams on a table?

After enabling DynamoDB Streams on a table, what is the immediate effect on the table's behavior?

A The table sends a summary report of changes to CloudWatch Logs.

B The table starts recording item-level changes as stream records for up to 24 hours.

C The table disables all write operations until the stream is processed.

D The table automatically backs up all data to S3 every 5 minutes.

💡 Hint

Consider what DynamoDB Streams stores and for how long.

When enabled, DynamoDB Streams records item-level changes as stream records and retains them for 24 hours for processing.

❓ Architecture

advanced

Designing a system to process DynamoDB Streams with Lambda

You want to process DynamoDB Streams records using AWS Lambda. Which architecture ensures that each stream record is processed exactly once and in order?

A Configure Lambda with batch size 1 and enable the 'bisect on function error' option.

B Use multiple Lambda functions triggered by the same stream to increase parallelism.

C Set Lambda batch size to maximum and disable retries to speed up processing.

D Process the stream records manually by polling the stream with a custom script.

💡 Hint

Think about how to maintain order and avoid duplicate processing.

Setting batch size to 1 and enabling 'bisect on function error' helps Lambda process each record exactly once and in order, handling errors gracefully.

❓ security

advanced

Securing access to DynamoDB Streams

Which IAM policy action is required to allow a Lambda function to read from a DynamoDB Stream?

A "lambda:InvokeFunction" and "dynamodb:DeleteStream"

B "dynamodb:PutItem" and "dynamodb:UpdateItem"

C "dynamodb:DescribeStream" and "dynamodb:GetRecords"

D "s3:GetObject" and "dynamodb:Scan"

💡 Hint

Focus on permissions related to reading stream data.

To read from DynamoDB Streams, the Lambda function needs permissions like "dynamodb:DescribeStream" and "dynamodb:GetRecords" to access stream details and records.

✅ Best Practice

expert

Handling stream record retention and data loss risks

DynamoDB Streams retains records for 24 hours. What is the best practice to avoid data loss if your stream processing application is down for longer than 24 hours?

A Use DynamoDB Streams with Kinesis Data Streams to extend retention and replay capability.

B Increase the stream retention period to 7 days in the DynamoDB table settings.

C Periodically back up the DynamoDB table and restore it if the stream is lost.

D Implement a dead-letter queue (DLQ) to capture failed stream records for later processing.

💡 Hint

Consider how to extend stream retention beyond the default limit.

DynamoDB Streams retention is fixed at 24 hours. Integrating with Kinesis Data Streams allows longer retention and replay, preventing data loss during downtime.