TTL with Streams for archival in DynamoDB - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ query_result

intermediate

What happens when an item expires with TTL enabled in DynamoDB?

Consider a DynamoDB table with TTL enabled on the attribute expiryTimestamp. What is the expected behavior when an item's TTL expires?

A The item is immediately deleted and a stream record of type REMOVE is generated.

B The item remains in the table until manually deleted; no stream record is generated.

C The item is archived automatically to S3 and removed from the table instantly.

D The item is deleted asynchronously after expiration and a stream record of type REMOVE is generated.

💡 Hint

TTL deletion is not immediate but happens asynchronously by DynamoDB.

DynamoDB TTL deletes expired items asynchronously, and when deleted, a stream record of type REMOVE is generated for that item.

🧠 Conceptual

intermediate

Why use DynamoDB Streams with TTL for archival?

What is the main reason to enable DynamoDB Streams when using TTL for archival purposes?

A To speed up the TTL deletion process by triggering immediate deletes.

B To capture expired item deletions so they can be archived elsewhere before removal.

C To prevent expired items from being deleted automatically.

D To automatically backup the entire table every time TTL deletes an item.

💡 Hint

Think about how you can keep a copy of deleted items.

Streams capture REMOVE events caused by TTL expiration, allowing you to archive the deleted items elsewhere before they are lost.

📝 Syntax

advanced

Which DynamoDB Stream event type corresponds to TTL deletion?

Given a DynamoDB Stream event record, which eventName indicates an item was deleted due to TTL expiration?

A "REMOVE"

B "INSERT"

C "MODIFY"

D "EXPIRE"

💡 Hint

TTL deletions remove items from the table.

TTL deletions generate a stream event with eventName set to "REMOVE" because the item is deleted.

🔧 Debug

advanced

Why is no stream record generated for expired items?

You enabled TTL and DynamoDB Streams on your table, but you notice no REMOVE events appear in the stream when items expire. What could be the cause?

A TTL deletions happen asynchronously and may take up to 48 hours to process, so no immediate stream events appear.

B Streams do not capture TTL deletions by design.

C The TTL attribute is not set as a Number type, so TTL is ignored and no deletions occur.

D The stream is configured to capture only INSERT events, so REMOVE events are filtered out.

💡 Hint

TTL deletions are asynchronous and can take up to 48 hours to appear in streams.

TTL deletions happen asynchronously and may take up to 48 hours to process, so no immediate stream events appear even after expiration.

❓ optimization

expert

Best practice for archiving expired DynamoDB items using TTL and Streams

You want to archive expired items from a DynamoDB table to S3 using TTL and Streams. Which approach optimizes cost and reliability?

A Enable TTL and Streams, but archive items directly from the stream without batching or retries.

B Disable TTL, and use Streams to capture all INSERT and MODIFY events, then archive items after a fixed time.

C Enable TTL and Streams, use a Lambda triggered by REMOVE events to batch and write expired items to S3 asynchronously.

D Enable TTL only, and run a scheduled job to scan the table for expired items and archive them manually.

💡 Hint

Think about asynchronous processing and batching for cost efficiency.

Using TTL with Streams and a Lambda triggered on REMOVE events allows efficient, reliable, and cost-effective archiving by batching writes to S3 asynchronously.