Put, get, and query operations in AWS - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ service_behavior

intermediate

DynamoDB PutItem operation behavior

You use the AWS DynamoDB PutItem operation to add an item with a primary key that already exists in the table. What happens to the existing item?

A The new item is merged with the existing item, updating only specified attributes.

B The PutItem operation fails with a ConditionalCheckFailedException.

C The existing item is replaced with the new item completely.

D The PutItem operation appends the new item as a duplicate entry.

💡 Hint

Think about how PutItem treats items with the same primary key.

PutItem replaces the entire existing item if the primary key matches. It does not merge or append duplicates.

❓ service_behavior

intermediate

DynamoDB GetItem consistency options

When you perform a GetItem operation in DynamoDB, which option ensures you get the most up-to-date data?

A Set the ConsistentRead parameter to true for a strongly consistent read.

B Use the default eventually consistent read option.

C Use a Query operation instead of GetItem.

D Enable DynamoDB Streams to get the latest data.

💡 Hint

Consider how DynamoDB handles read consistency.

Setting ConsistentRead to true in GetItem returns strongly consistent data, ensuring the latest updates are read.

❓ Configuration

advanced

DynamoDB Query operation with filter expression

You want to retrieve all items from a DynamoDB table where the partition key is 'User123' and the attribute 'Status' equals 'Active'. Which Query operation parameters correctly achieve this?

AWS

TableName: 'Users'
KeyConditionExpression: 'UserId = :uid'
FilterExpression: 'Status = :status'
ExpressionAttributeValues: { ':uid': {S: 'User123'}, ':status': {S: 'Active'} }

A Use only FilterExpression for both UserId and Status.

B Use KeyConditionExpression for both UserId and Status attributes.

C Use FilterExpression for UserId and KeyConditionExpression for Status.

D Use KeyConditionExpression for UserId and FilterExpression for Status.

💡 Hint

Remember that KeyConditionExpression must include the partition key.

KeyConditionExpression filters by partition key and optionally sort key. FilterExpression filters non-key attributes after the query.

❓ Architecture

advanced

Efficient retrieval of multiple items by keys

You need to retrieve multiple items from a DynamoDB table by their primary keys in a single request. Which operation is the most efficient and appropriate?

A Use multiple GetItem requests in parallel.

B Use BatchGetItem operation with all keys specified.

C Use Query operation with multiple KeyConditionExpressions.

D Use Scan operation with a filter on primary keys.

💡 Hint

Consider which operation supports multiple keys in one call.

BatchGetItem allows retrieving multiple items by primary keys in a single request efficiently.

❓ security

expert

Securing DynamoDB PutItem operations with IAM policies

You want to restrict an IAM user so they can only perform PutItem operations on a DynamoDB table but only for items where the attribute 'Department' equals 'Sales'. Which IAM policy condition correctly enforces this?

A "Condition": {"StringEquals": {"dynamodb:Attributes/Department": "Sales"}}

B "Condition": {"ForAllValues:StringEquals": {"dynamodb:Attributes/Department": "Sales"}}

C "Condition": {"StringEqualsIfExists": {"dynamodb:LeadingKeys": ["Sales"]}}

D "Condition": {"StringEquals": {"dynamodb:LeadingKeys": ["Sales"]}}

💡 Hint

Think about how to restrict based on an attribute value in IAM conditions.

The condition "StringEquals" on "dynamodb:Attributes/Department" restricts PutItem to items where Department equals 'Sales'.