AWS DynamoDB Scenario based Questions ❓

Related to the AWS DynamoDB :: These are the scenario based questions for the AWS DynamoDB working model

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❓You need to design a DynamoDB table to store user profile data, including username, email, and user ID. How would you structure the primary key?

Answer: Use userID as the partition key.

The userID is unique for each user and ensures that each item can be retrieved directly and efficiently.

❓You have a table with millions of items. You need to retrieve all items where the status attribute is “active”. What DynamoDB operation would you use?

Answer: Use the Scan operation.

A Scan operation examines every item in the table to find all items with the specified attribute value, but it’s less efficient than a query.

❓You need to ensure that the email attribute is unique across all items in the user table. How would you enforce this uniqueness in DynamoDB?

Answer: Use a global secondary index (GSI) with email as the partition key.

A GSI with email as the partition key ensures that emails are unique across the table.

❓You need to store time-series data for sensor readings with each reading having a timestamp. How would you structure the table’s primary key?

Answer: Use sensorID as the partition key and timestamp as the sort key.

This allows you to efficiently retrieve all readings for a specific sensor ordered by time.

❓ You want to back up your DynamoDB table daily. Which feature would you use?

Answer: Use DynamoDB’s On-Demand Backup and Restore.

This feature allows you to create full backups of your tables for data recovery.

❓ Your application requires read and write operations to be processed within a few milliseconds. How would you configure DynamoDB for this requirement?

Answer: Use provisioned throughput with sufficient read and write capacity units.

Ensuring enough capacity units helps maintain low latency for read and write operations.

❓ You need to retrieve items from a DynamoDB table where the partition key is known but the sort key is only partially known. Which query option would you use?

Answer: Use the begins_with condition in a query.

This allows you to query items where the sort key starts with a specific prefix.

❓You need to ensure that your DynamoDB table is available in multiple regions for disaster recovery. Which feature would you use?

Answer: Use DynamoDB Global Tables.

Global Tables automatically replicate your data across multiple regions.

❓You need to temporarily increase the read capacity of your table to handle a traffic spike. What would you do?

Answer: Use the UpdateTable operation to increase the provisioned read capacity.

This allows you to handle increased read traffic by temporarily boosting the read capacity.

❓Your application requires strongly consistent reads. How would you configure your DynamoDB read operations?

Answer: Set the ConsistentRead parameter to true.

This ensures that the read operation returns the most up-to-date data.

❓You need to perform a bulk write operation to load initial data into your DynamoDB table. Which method would you use?

Answer: Use the BatchWriteItem API.

BatchWriteItem allows you to perform multiple put and delete operations in a single request.

❓You have a table where items are frequently updated. You need to capture and process these changes in real-time. What feature would you use?

Answer: Enable DynamoDB Streams.

DynamoDB Streams capture data modification events in a table and allow you to process these changes.

❓You want to ensure that a write operation only occurs if the item does not already exist. How would you implement this?

Answer: Use a conditional expression with the PutItem operation.

The conditional expression can check for the absence of the item before allowing the write.

❓Scenario: You need to paginate results from a Query operation. How would you achieve this?

Answer: Use the LastEvaluatedKey returned by the query and pass it as ExclusiveStartKey in subsequent queries.

This allows you to retrieve the next set of results in a paginated fashion.

❓Your table has a large amount of read-heavy traffic. To improve performance, you decide to use a caching solution. Which AWS service would you integrate with DynamoDB?

Answer: Use Amazon DynamoDB Accelerator (DAX).

DAX is a fully managed caching service that improves read performance for DynamoDB.

❓You need to update multiple items in a single transaction. Which feature would you use?

Answer: Use TransactWriteItems.

This allows you to perform multiple write operations in a single atomic transaction.

❓You need to calculate the total number of items in a DynamoDB table. How would you do this?

Answer: Use the Scan operation with a Count attribute.

The Scan operation can return the total count of items without retrieving the actual items.

❓You need to restrict access to certain items in your DynamoDB table based on the user’s role. How would you implement this?

Answer: Use IAM policies with condition expressions.

IAM policies can enforce fine-grained access control based on item attributes.

❓You need to retrieve only specific attributes of an item to minimize data transfer. How would you configure your read request?

Answer: Use the ProjectionExpression parameter in the GetItem or Query request.

ProjectionExpression allows you to specify which attributes to retrieve.

❓You need to archive items that haven’t been accessed in the last year. How would you identify these items?

Answer: Use a Scan operation with a filter expression based on a timestamp attribute.

This allows you to find items that haven’t been accessed within the specified timeframe.

❓You need to delete multiple items from a DynamoDB table based on a condition. How would you do this?

Answer: Use BatchWriteItem with conditional expressions.

BatchWriteItem allows you to delete multiple items, and conditional expressions ensure the deletions meet specific criteria.

❓Your DynamoDB table needs to support complex queries involving multiple attributes. Which index would you use?

Answer: Use a global secondary index (GSI).

GSIs allow you to create indexes on attributes other than the primary key, supporting more complex queries.

❓ You want to automate the scaling of read and write capacity for your DynamoDB table based on traffic patterns. Which feature would you use?

Answer: Enable DynamoDB Auto Scaling.

Auto Scaling adjusts the provisioned capacity based on the specified scaling policies and traffic patterns.

❓You need to retrieve items from two different DynamoDB tables in a single request. How would you achieve this?

Answer: Use the BatchGetItem API.

BatchGetItem allows you to retrieve items from multiple tables in a single request.

❓Your application needs to store large binary objects (e.g., images) alongside other item attributes. How would you handle this in DynamoDB?

Answer: Store the binary objects in Amazon S3 and save the S3 object URL in DynamoDB.

This approach offloads large binary storage to S3 while keeping metadata in DynamoDB, optimizing storage and retrieval.

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