PERSIST to remove expiry in Redis - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the Redis PERSIST command do?

The PERSIST command removes the expiration time from a key, making it persistent (no longer set to expire).

beginner

How do you remove the expiry from a Redis key named session123?

Use the command: PERSIST session123 to remove its expiration.

intermediate

What happens if you run PERSIST on a key that does not have an expiry?

The command returns 0, meaning no expiration was removed because the key was already persistent.

beginner

Why would you want to use PERSIST in Redis?

To keep important data from being deleted automatically by removing its expiration time.

intermediate

What is the return value of PERSIST when it successfully removes the expiry?

It returns 1 to indicate the expiration was removed successfully.

What does the Redis command PERSIST key do?

A Renames the key

B Removes the expiration time from the key

C Deletes the key immediately

D Sets a new expiration time on the key

The PERSIST command removes any expiration time, making the key persistent.

If a key has no expiration, what does PERSIST key return?

A Error

B 1

C -1

D 0

It returns 0 because there was no expiration to remove.

Which Redis command would you use to prevent a key from expiring?

A EXPIRE

B TTL

C PERSIST

D DEL

PERSIST removes the expiry, so the key stays forever.

What is the effect of running PERSIST on a key with a 10-second expiry?

A The key no longer expires

B The key expires immediately

C The key expires in 10 seconds

D The expiry is extended by 10 seconds

PERSIST removes the expiry, so the key will not expire.

Which of these is NOT true about the Redis PERSIST command?

A It sets a new expiration time

B It removes the expiration from a key

C It can be used to keep data permanently

D It returns 1 if expiry was removed

PERSIST does not set expiration; it removes it.

Explain how the Redis PERSIST command works and when you might use it.

Think about how to stop a key from disappearing automatically.

Describe what happens if you run PERSIST on a key that already has no expiration set.

Consider the return value and effect on the key.