Jeff’s Note #
Unlike generic exam dumps, ADH analyzes this scenario through the lens of a Real-World Lead Developer.
For AWS DVA-C02 candidates, the confusion often lies in choosing the most efficient integration point without overhauling existing application code. In production, this is about knowing exactly how to leverage AWS managed event sources to trigger processing with near real-time guarantees, while minimizing operational complexity and code refactoring. Let’s drill down.
The Certification Drill (Simulated Question) #
Scenario #
TechNova Solutions runs a mission-critical document management platform that stores millions of records in Amazon DynamoDB. The system handles between 30 to 60 document updates per minute. The development team needs to process newly added or updated records almost instantly once they are committed to the database. The requirement is to implement this near-real-time processing mechanism with the least disruption or modification to the existing application logic.
The Requirement: #
Design a solution that triggers document processing immediately after DynamoDB inserts or updates, with minimal changes to the current app codebase.
The Options #
- A) Schedule a cron job on an Amazon EC2 instance that runs hourly, querying the DynamoDB table for recent changes and processing those documents.
- B) Enable DynamoDB Streams on the table and configure an AWS Lambda function to automatically process newly added or updated documents.
- C) Modify the application to send PutEvents requests directly to Amazon EventBridge, with an EventBridge rule invoking a Lambda function for processing.
- D) Change the application to synchronously process documents immediately after writing each record to DynamoDB.
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Correct Answer #
B
Quick Insight: The Developer Imperative #
- For Developers: The key is minimizing invasive code changes and leveraging AWS managed integrations. DynamoDB Streams paired with Lambda offers a native, event-driven, and near real-time processing pipeline with minimal developer effort.
- Other options either increase latency, operational burden, or require synchronous blocking logic that impacts throughput.
Content Locked: The Expert Analysis #
You’ve identified the answer. But do you know the implementation details that separate a Junior from a Senior?
The Expert’s Analysis #
Correct Answer #
Option B
The Winning Logic #
Using DynamoDB Streams is the most elegant and efficient way to capture real-time changes in your table. Enabling Streams on a DynamoDB table produces a time-ordered sequence of item-level changes (inserts, updates, deletes). AWS Lambda can be configured as an event source for these streams, automatically invoking your function whenever data changes occur. This means processing logic can be decoupled from the application write operation, ensuring minimal to no changes needed in the existing app code.
Additional advantages:
- Near real-time processing vs. batch scheduling.
- Fully managed, scalable integration with AWS Lambda.
- Automatically handles multiple events, retries on errors.
- Low operational overhead — no extra servers or cron jobs to maintain.
The Trap (Distractor Analysis): #
-
Why not A?
Running an hourly cron job on EC2 introduces latency (up to one hour delay) and operational overhead managing instances. It’s a batch approach, not near real-time, and requires custom scripts to track changes, complicating implementation. -
Why not C?
Modifying the app to synchronously call PutEvents on EventBridge adds development complexity and code changes. You also introduce extra API calls and dependencies—when DynamoDB Streams natively provide the event data without modifying write logic. -
Why not D?
Synchronous processing after each write negatively affects application throughput and user experience by making the app wait for processing to complete. It also tightly couples processing logic, reducing scalability and robustness.
The Technical Blueprint #
# Example CLI command to enable DynamoDB Streams (NEW_AND_OLD_IMAGES for full data)
aws dynamodb update-table \
--table-name DocumentStore \
--stream-specification StreamEnabled=true,StreamViewType=NEW_AND_OLD_IMAGES
# Lambda event source mapping to the stream ARN
aws lambda create-event-source-mapping \
--function-name ProcessDocumentLambda \
--event-source-arn arn:aws:dynamodb:region:account-id:table/DocumentStore/stream/YYYYMMDDHHMMSS \
--starting-position LATEST
The Comparative Analysis #
| Option | API Complexity | Performance | Use Case |
|---|---|---|---|
| A | Low | High Latency | Batch processing, legacy support |
| B | Moderate | Near Real-time | Event-driven processing with minimal code change |
| C | High | Near Real-time | Requires app code changes and extra API calls |
| D | High | Synchronous, potential bottleneck | Tight coupling, impacts throughput |
Real-World Application (Practitioner Insight) #
Exam Rule #
For the exam, always pick DynamoDB Streams + Lambda when you see near real-time processing from DynamoDB changes with minimal app code changes.
Real World #
In production, you might later integrate EventBridge for more complex event routing or multi-service orchestration, but that involves more upfront development work and is not minimal-change.
(CTA) Stop Guessing, Start Mastering #
Disclaimer
This is a study note based on simulated scenarios for the AWS DVA-C02 exam.