Boto3 (Python) client vs resource in DynamoDB - Practice Questions

Challenge - 5 Problems

🧠 Conceptual

intermediate

Difference in method usage between client and resource

Which statement correctly describes how you would retrieve an item from a DynamoDB table using Boto3 client vs resource?

A Client uses get_item with TableName parameter; resource uses Table object with get_item method without TableName.

B Client and resource do not support get_item method.

C Both client and resource require TableName parameter in get_item method.

D Client uses Table object with get_item method; resource uses get_item with TableName parameter.

💡 Hint

Think about how client and resource interfaces differ in method calls.

The client interface requires explicit parameters like TableName in methods such as get_item. The resource interface provides higher-level abstractions like Table objects where methods like get_item do not require TableName because the Table object already represents a specific table.

❓ query_result

intermediate

Output of scan operation using client vs resource

Given the following code snippets, what is the type of the output returned by each scan operation? Client: ```python dynamodb_client = boto3.client('dynamodb') response = dynamodb_client.scan(TableName='MyTable') ``` Resource: ```python dynamodb_resource = boto3.resource('dynamodb') table = dynamodb_resource.Table('MyTable') response = table.scan() ```

A Client returns a dict with raw DynamoDB JSON; resource returns a dict with Python native types.

B Client returns a list of items; resource returns a dict with raw DynamoDB JSON.

C Both client and resource return a list of items as Python dicts.

D Client returns a dict with Python native types; resource returns a list of items.

💡 Hint

Consider how Boto3 client and resource handle data types in responses.

The client returns raw DynamoDB JSON format where attribute values are typed (e.g., {'S': 'string'}). The resource automatically converts these into native Python types (e.g., strings, numbers) in the returned dict.

📝 Syntax

advanced

Correct syntax to update an item using resource

Which of the following code snippets correctly updates an attribute 'status' to 'active' for a given key in a DynamoDB table using Boto3 resource?

A table.update_item(Key={'id': '123'}, UpdateExpression='SET status = active')

B table.update_item(Key={'id': '123'}, UpdateExpression='SET status = :val', ExpressionAttributeValues={':val': {'S': 'active'}})

C table.update_item(Key={'id': '123'}, UpdateExpression='SET status = :val', ExpressionAttributeValues={':val': 'active'})

D table.update_item(Key={'id': '123'}, UpdateExpression='SET status = :val', ExpressionAttributeValues={':val': active})

💡 Hint

Remember how resource expects Python native types in ExpressionAttributeValues.

When using resource, ExpressionAttributeValues should be Python native types, not DynamoDB JSON format. Option C correctly uses a string value 'active'. Option C incorrectly uses DynamoDB JSON format. Option C misses ExpressionAttributeValues. Option C uses an undefined variable active.

❓ optimization

advanced

Choosing client or resource for batch writes

You want to write 1000 items to a DynamoDB table efficiently. Which approach is better and why?

A Use resource's put_item method for each item because it is simpler.

B Use resource's batch_writer() because it automatically handles buffering and retries.

C Use client put_item in a loop because it gives more control over each write.

D Use client batch_write_item with single item per request for simplicity.

💡 Hint

Think about how batch_writer helps with large writes.

Resource's batch_writer() manages buffering, batch sizes, and retries automatically, making it efficient for large writes. Client requires manual batching and retry logic, which is more complex and error-prone.

🔧 Debug

expert

Why does this client code raise a ValidationException?

Consider this client code snippet: ```python response = dynamodb_client.get_item(Key={'id': '123'}, TableName='MyTable') ``` It raises a ValidationException with message: "One or more parameter values were invalid: Type mismatch for key id expected: S actual: N". What is the cause?

A The key value '123' is passed as a plain string instead of DynamoDB JSON format with type.

B The TableName parameter is missing from the get_item call.

C The key attribute 'id' is missing from the Key dictionary.

D The key value type does not match the table's key schema; it expects a string but got a number.

💡 Hint

Check the expected data type of the key attribute in the table schema.

The error indicates a type mismatch: the table expects a string (S) for the 'id' key, but the actual value is a number (N). Passing '123' as a plain string without DynamoDB JSON format is correct for resource but client expects the value wrapped with type. However, the main issue is the type mismatch between expected and actual key type.