Why memory optimization matters in Redis - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set a key with an expiration time in Redis.

Redis

SET mykey myvalue EX [1]

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

ADEL

Bmyvalue

C60

DGET

Attempts:

3 left

💡 Hint

Common Mistakes

Using a command like GET instead of a number for expiration.

Forgetting to specify the expiration time after EX.

The EX option sets the expiration time in seconds. Here, 60 means the key expires after 60 seconds.

2fill in blank

medium

Complete the command to check the memory usage of a key in Redis.

Redis

MEMORY [1] mykey

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

AUSAGE

BGET

CDEL

DSET

Attempts:

3 left

💡 Hint

Common Mistakes

Using GET or DEL instead of USAGE.

Not specifying the key after the command.

The MEMORY USAGE command returns the number of bytes used by the key.

3fill in blank

hard

Fix the error in the command to delete all keys matching a pattern.

Redis

KEYS [1] | xargs [2]

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

A*

BDEL

CGET

DSET

Attempts:

3 left

💡 Hint

Common Mistakes

Using DEL, GET, or SET as the pattern instead of '*'.

Using xargs with GET or SET instead of DEL.

Not using a wildcard pattern to match keys.

The KEYS * command lists all keys using the wildcard pattern *. Pipe to xargs DEL to delete them. Warning: Avoid in production; use SCAN instead for large datasets.

4fill in blank

hard

Fill both blanks to create a Redis command that sets a key only if it does not exist and expires after 120 seconds.

Redis

SET mykey myvalue [1] [2] 120

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

ANX

BXX

CEX

DPX

Attempts:

3 left

💡 Hint

Common Mistakes

Using XX instead of NX, which sets only if the key exists.

Using PX instead of EX, which sets expiration in milliseconds.

NX means set the key only if it does not exist. EX sets the expiration time in seconds.

5fill in blank

hard

Fill all three blanks to create a Redis command that sets a counter key with expiration in milliseconds.

Redis

SET [1] 1 [2] [3]

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

Amycounter

BPX

C60000

DEX

Attempts:

3 left

💡 Hint

Common Mistakes

Using EX instead of PX for milliseconds.

Not specifying the key name.

Wrong expiration time value.

mycounter is the key for the counter. PX sets expiration in milliseconds. 60000 means 60 seconds.