TTL behavior and timing in DynamoDB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does TTL stand for in DynamoDB?

TTL stands for Time To Live. It is a feature that automatically deletes expired items from a DynamoDB table.

beginner

How does DynamoDB determine when to delete an item using TTL?

DynamoDB checks the timestamp attribute you specify for TTL. When the current time passes this timestamp, the item becomes eligible for deletion.

intermediate

Does DynamoDB delete expired items immediately after the TTL timestamp passes?

No. DynamoDB deletes expired items within 48 hours after the TTL timestamp passes. The deletion is not immediate but happens asynchronously.

intermediate

What happens if you update the TTL attribute of an item before it expires?

If you update the TTL attribute to a new future timestamp, DynamoDB will use the updated timestamp to determine when to delete the item. This can delay or cancel the deletion.

advanced

Can you recover an item after DynamoDB deletes it due to TTL expiration?

No. Once DynamoDB deletes an item due to TTL expiration, it cannot be recovered. You should back up important data before it expires.

What is the main purpose of TTL in DynamoDB?

A Automatically delete expired items

B Encrypt data at rest

C Backup data regularly

D Improve query speed

TTL automatically deletes items after their expiration time to save storage and manage data lifecycle.

When does DynamoDB delete an item after its TTL timestamp has passed?

A Immediately

B After 7 days

C Within 48 hours

D Only when manually triggered

DynamoDB deletes expired items asynchronously within 48 hours after the TTL timestamp.

Which attribute type must the TTL attribute be in DynamoDB?

A String

B List

C Boolean

D Number (Unix epoch time in seconds)

TTL attribute must be a Number representing Unix epoch time in seconds.

If you remove the TTL attribute from an item before expiration, what happens?

A Item is deleted immediately

B Item will not be deleted by TTL

C Item is archived

D Item is locked

Without the TTL attribute, DynamoDB does not consider the item for TTL deletion.

Can TTL be used to trigger custom actions when an item expires?

A Yes, via DynamoDB Streams and Lambda

B No, TTL only deletes items

C Yes, directly within DynamoDB

D No, TTL archives items instead

You can use DynamoDB Streams with Lambda to react to item deletions caused by TTL.

Explain how TTL works in DynamoDB and its timing behavior.

Think about how DynamoDB knows when to delete and when it actually deletes.

Describe what happens if you update or remove the TTL attribute on an item before it expires.

Consider how DynamoDB uses the TTL attribute to decide deletion.