Key expiry for memory management in Redis - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set a key with an expiry time of 60 seconds.

Redis

SET mykey "value" EX [1]

Drag options to blanks, or click blank then click option'

A0

B30

C60

D120

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 as expiry disables expiry, so the key never expires.

Confusing milliseconds with seconds.

The EX option sets the expiry time in seconds. Here, 60 seconds is the correct expiry time.

2fill in blank

medium

Complete the code to set a key to expire in 5 minutes using the PX option (milliseconds).

Redis

SET session_token "abc123" PX [1]

Drag options to blanks, or click blank then click option'

A300000

B3000

C5000

D60000

Attempts:

3 left

💡 Hint

Common Mistakes

Using 3000 instead of 300000, confusing seconds and milliseconds.

Using PX with seconds value instead of milliseconds.

The PX option sets expiry in milliseconds. 5 minutes = 5 * 60 * 1000 = 300000 ms.

3fill in blank

hard

Fix the error in the command to set a key to expire in 10 seconds.

Redis

SET user_id "12345" EX [1]

Drag options to blanks, or click blank then click option'

A-10

B10

C0

D10000

Attempts:

3 left

💡 Hint

Common Mistakes

Using 10000 which is milliseconds, not seconds.

Using negative or zero values which are invalid.

The EX option expects seconds, so 10 is correct. 10000 ms = 10 s, but EX takes seconds directly.

4fill in blank

hard

Fill both blanks to set a key with expiry and then check its remaining TTL.

Redis

SET cache_key "data" EX [1]
TTL [2]

Drag options to blanks, or click blank then click option'

A120

Bcache_key

Cmykey

D60

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different key name in TTL than the one set.

Using wrong expiry time units.

First, set the key cache_key to expire in 120 seconds. Then, check TTL of cache_key.

5fill in blank

hard

Fill all three blanks to set a key with expiry, update its expiry, and check the new TTL.

Redis

SET temp_key "value" EX [1]
EXPIRE [2] [3]
TTL temp_key

Drag options to blanks, or click blank then click option'

Atemp_key

B300

C600

Dcache_key

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong key name in EXPIRE command.

Confusing expiry times or units.

Set temp_key to expire in 300 seconds, then update expiry to 600 seconds using EXPIRE, and finally check TTL.