RENAME and RENAMENX in Redis - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ query_result

intermediate

What is the result of RENAME when the new key exists?

Assume the Redis database has keys: key1 with value 100 and key2 with value 200. What happens after running RENAME key1 key2?

Redis

SET key1 100
SET key2 200
RENAME key1 key2
GET key2

A Returns an error because key2 already exists

B Deletes both keys and returns nil

C Does nothing and returns OK; GET key2 returns 200

D Renames key1 to key2, overwriting the old key2 value; GET key2 returns 100

💡 Hint

RENAME overwrites the destination key if it exists.

The RENAME command changes the key name even if the new key exists, overwriting its value.

❓ query_result

intermediate

What does RENAMENX return if the new key exists?

Given keys alpha with value foo and beta with value bar, what is the return value of RENAMENX alpha beta?

Redis

SET alpha foo
SET beta bar
RENAMENX alpha beta

A 0, because beta already exists and rename did not happen

B 1, because the rename succeeded

C An error because beta exists

D nil, because alpha does not exist

💡 Hint

RENAMENX only renames if the new key does not exist.

RENAMENX returns 0 and does not rename if the new key exists.

📝 Syntax

advanced

Which command syntax is correct to rename a key only if the new key does not exist?

Choose the correct Redis command syntax to rename oldkey to newkey only if newkey does not exist.

A RENAMENX oldkey newkey

B RENAME oldkey newkey NX

C RENAME IF NOT EXISTS oldkey newkey

D RENAMEX oldkey newkey

💡 Hint

The command is RENAMENX, not RENAME with options.

RENAMENX is the correct command to rename only if the new key does not exist.

🧠 Conceptual

advanced

What happens if you RENAME a key to the same key name?

If you run RENAME mykey mykey in Redis, what is the result?

A Returns an error because source and destination are the same

B Deletes the key

C Returns OK and does nothing

D Renames the key to a new random key

💡 Hint

RENAME returns OK even if source and destination are the same.

The RENAME command returns OK even when the source and destination keys are the same, and the key remains unchanged.

🔧 Debug

expert

Why does RENAMENX fail to rename when the new key does not exist?

You run these commands: SET a 1 DEL b RENAMENX a b But RENAMENX returns 0 and does not rename. What is the most likely cause?

Redis

SET a 1
DEL b
RENAMENX a b

A Key 'b' still exists, so RENAMENX refuses to rename

B Key 'a' does not exist at the time of RENAMENX

C RENAMENX cannot rename keys with numeric values

D RENAMENX requires both keys to exist

💡 Hint

Check if the source key exists before renaming.

RENAMENX returns 0 if the source key does not exist, even if the destination key is missing.