Temporary data with TTL in Redis - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does TTL stand for in Redis?

TTL stands for Time To Live. It is the duration a key will exist before Redis automatically deletes it.

beginner

How do you set a key with a TTL in Redis?

Use the SET command with the EX option, like SET key value EX 10 to set a key that expires in 10 seconds.

beginner

What happens when a Redis key's TTL expires?

Redis automatically deletes the key, so it no longer exists in the database.

beginner

How can you check the remaining TTL of a key in Redis?

Use the TTL key command. It returns the remaining time in seconds before the key expires.

intermediate

Can you update the TTL of an existing key in Redis?

Yes, use the EXPIRE key seconds command to set or update the TTL of an existing key.

Which Redis command sets a key with a TTL of 30 seconds?

A GET mykey EX 30

B SET mykey myvalue EX 30

C TTL mykey 30

D EXPIRE mykey 30

The SET command with EX 30 sets the key and its TTL in one step.

What does the Redis command TTL mykey return if the key does not have a TTL?

A -1

B 0

C null

D -2

Redis returns -1 if the key exists but has no expiration set.

If a key's TTL expires, what happens to the key?

A It is deleted automatically

B It remains but becomes read-only

C Its value is set to null

D It is moved to a backup database

Redis deletes keys automatically when their TTL expires.

Which command updates the TTL of an existing key to 60 seconds?

A SET key value EX 60

B TTL key 60

C EXPIRE key 60

D GET key EX 60

The EXPIRE command sets or updates the TTL of an existing key.

How can you create a key that never expires in Redis?

A Use TTL command with -1

B Use EXPIRE with 0 seconds

C Use SET with EX 0

D Set the key without any TTL

Keys without TTL never expire unless deleted manually.

Explain how Redis uses TTL to manage temporary data.

Think about how Redis automatically removes data after some time.

Describe how to set, check, and update TTL for a Redis key.

Focus on the commands that control expiration.