Tables, items, and attributes in AWS - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding DynamoDB Table Keys

In AWS DynamoDB, what is the primary difference between a partition key and a sort key in a table?

A Partition key determines the partition for each item, while sort key allows multiple items with the same partition key but different sort keys.

B Sort key uniquely identifies each item, while partition key allows multiple items with the same sort key but different partition keys.

C Partition key and sort key both must be unique across the entire table.

D Partition key is optional, but sort key is mandatory for all tables.

💡 Hint

Think about how DynamoDB organizes data to allow efficient queries.

The partition key determines the partition where data is stored. The sort key allows multiple items to share the same partition key but be distinguished by the sort key.

❓ Configuration

intermediate

DynamoDB Item Attribute Types

Which of the following JSON representations correctly defines a DynamoDB item with a string attribute 'Name' and a number attribute 'Age'?

A {"Name": "Alice", "Age": 30}

B {"Name": {"SS": ["Alice"]}, "Age": {"NS": ["30"]}}

C {"Name": {"N": "Alice"}, "Age": {"S": "30"}}

D {"Name": {"S": "Alice"}, "Age": {"N": "30"}}

💡 Hint

DynamoDB expects attribute values to be typed explicitly in JSON format.

DynamoDB JSON format requires attribute values to be objects with a type key such as 'S' for string and 'N' for number, with the value as a string.

❓ Architecture

advanced

Designing a DynamoDB Table for High Write Throughput

You need to design a DynamoDB table to handle very high write throughput evenly distributed across partitions. Which table key design helps avoid hot partitions?

A Use only a sort key without a partition key.

B Use a partition key with sequential numeric values.

C Use a composite key with a high-cardinality partition key and a sort key.

D Use a simple partition key with low cardinality values.

💡 Hint

Think about how DynamoDB partitions data and distributes load.

A high-cardinality partition key spreads writes across many partitions, preventing hot spots. A composite key with a sort key allows efficient queries and balanced writes.

❓ security

advanced

Controlling Access to Specific Attributes in DynamoDB

How can you restrict a user’s access to only certain attributes of items in a DynamoDB table?

A Use IAM policies with condition keys to allow access only to specific attributes.

B Create a separate table with only the allowed attributes and give access to that table.

C Use DynamoDB Streams to filter attributes before access.

D Encrypt the attributes you want to restrict.

💡 Hint

Consider AWS IAM fine-grained access control features.

IAM policies can use condition keys like dynamodb:Attributes to restrict access to specific attributes within items.

❓ service_behavior

expert

DynamoDB Consistency Model Impact on Reads

If you perform a strongly consistent read on a DynamoDB table immediately after writing an item, what is the expected behavior?

A The read may return stale data due to eventual consistency.

B The read always returns the latest written data.

C The read will fail if the write is not yet fully replicated.

D The read returns data only if the item has a sort key.

💡 Hint

Think about the difference between eventually consistent and strongly consistent reads.

Strongly consistent reads always return the most recent data after a successful write, ensuring no stale data is returned.