TTL attribute setup in DynamoDB - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding TTL attribute purpose

What is the main purpose of setting a TTL (Time To Live) attribute on a DynamoDB table item?

A To automatically delete items after a specified time to reduce storage costs

B To encrypt the item data for security purposes

C To create a backup of the item before deletion

D To increase the read capacity of the table temporarily

💡 Hint

Think about why you would want items to disappear automatically.

TTL attribute marks items with an expiration timestamp. DynamoDB automatically deletes expired items to save storage and cost.

❓ query_result

intermediate

TTL attribute data type and value

Which of the following is the correct data type and value format for a TTL attribute in DynamoDB?

A A boolean value indicating if the item should expire

B A string representing a date in ISO 8601 format, e.g., "2024-06-01T12:00:00Z"

C A number representing the Unix epoch time in seconds when the item expires

D A map containing the expiration date and time

💡 Hint

TTL uses a timestamp in seconds since 1970-01-01.

DynamoDB TTL expects a number representing the Unix epoch time in seconds for expiration.

📝 Syntax

advanced

Enabling TTL on a DynamoDB table

Which AWS CLI command correctly enables TTL on a DynamoDB table with the TTL attribute named 'expireAt'?

A aws dynamodb update-table --table-name MyTable --ttl Enabled expireAt

B aws dynamodb update-time-to-live --table-name MyTable --time-to-live-specification Enabled=true,AttributeName=expireAt

C aws dynamodb set-ttl --table-name MyTable --ttl-attribute expireAt --enable

D aws dynamodb enable-ttl --table MyTable --attribute expireAt

💡 Hint

Check the official AWS CLI command syntax for TTL update.

The correct command uses update-time-to-live with a JSON-like specification for enabling TTL and specifying the attribute name.

❓ optimization

advanced

Optimizing TTL attribute usage

To optimize the TTL feature and avoid unexpected data retention, which practice is recommended when setting the TTL attribute value?

A Set the TTL attribute to the current time to delete items immediately

B Do not set the TTL attribute; rely on manual deletion instead

C Set the TTL attribute to a timestamp far in the past to trigger instant deletion

D Set the TTL attribute to a timestamp at least 24 hours in the future to allow for processing delays

💡 Hint

TTL deletion is not immediate; allow some buffer time.

Setting TTL slightly in the future ensures DynamoDB processes the expiration properly without premature deletion.

🔧 Debug

expert

Troubleshooting TTL not deleting expired items

You enabled TTL on your DynamoDB table with attribute 'expireAt', but expired items are not being deleted after several days. What is the most likely cause?

A The TTL attribute values are stored as strings instead of numbers

B The table's read capacity is too low to process TTL deletions

C The TTL attribute name is misspelled in the update-time-to-live command

D DynamoDB does not support TTL on tables with global secondary indexes

💡 Hint

TTL attribute must be a number, not a string.

If TTL attribute values are strings, DynamoDB cannot interpret expiration times, so items won't be deleted.