DEL and UNLINK for deletion in Redis - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the DEL command do in Redis?

DEL removes the specified keys from the database immediately and synchronously.

intermediate

How does the UNLINK command differ from DEL in Redis?

UNLINK removes keys asynchronously by unlinking them from the keyspace and freeing memory in the background.

intermediate

When should you prefer using UNLINK over DEL?

Use UNLINK when you want to avoid blocking Redis during large key deletions, improving performance.

beginner

What happens if you try to DEL or UNLINK a key that does not exist?

Both DEL and UNLINK return 0 and do nothing if the key does not exist.

beginner

Can DEL and UNLINK delete multiple keys at once?

Yes, both commands accept multiple keys and delete all specified keys in one call.

Which Redis command deletes keys asynchronously?

A DEL

B UNLINK

C EXPIRE

D FLUSHDB

UNLINK deletes keys asynchronously, freeing memory in the background.

What does DEL do when deleting a large key?

A Returns an error

B Deletes it asynchronously

C Renames the key

D Deletes it immediately and blocks Redis

DEL deletes keys immediately and can block Redis if the key is large.

If a key does not exist, what is the return value of DEL or UNLINK?

A 0

B Error

C 1

D Null

Both DEL and UNLINK return 0 when the key does not exist.

Which command would you use to avoid blocking Redis during key deletion?

A UNLINK

B SET

C GET

D DEL

UNLINK frees memory asynchronously, avoiding blocking Redis.

Can DEL and UNLINK delete multiple keys in one command?

A Only DEL can

B No

C Yes

D Only UNLINK can

Both DEL and UNLINK accept multiple keys to delete at once.

Explain the difference between DEL and UNLINK commands in Redis.

Think about how each command affects Redis performance during deletion.

When would you choose UNLINK over DEL in a Redis database?

Consider the impact on Redis responsiveness.