TYPE command for key type check in Redis - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ query_result

intermediate

Check the type of a string key

Given a Redis database where the key user:1000 holds the value "Alice" as a string, what will be the output of the command TYPE user:1000?

Redis

TYPE user:1000

A "list"

B "string"

C "set"

D "none"

💡 Hint

Remember that Redis stores simple text values as strings.

The TYPE command returns the data type of the key. Since user:1000 holds a string value, the output is "string".

❓ query_result

intermediate

Check type of a non-existing key

What will the command TYPE session:9999 return if the key session:9999 does not exist in the Redis database?

Redis

TYPE session:9999

A "empty"

B "null"

C "error"

D "none"

💡 Hint

Think about what Redis returns when a key is missing.

Redis returns "none" when the key does not exist.

❓ query_result

advanced

Identify the type of a sorted set key

If the key leaderboard contains a sorted set of player scores, what will TYPE leaderboard return?

Redis

TYPE leaderboard

A "zset"

B "set"

C "hash"

D "list"

💡 Hint

Sorted sets have a special type name in Redis.

Redis uses "zset" to represent sorted sets.

❓ query_result

advanced

Detect type of a hash key

What is the output of TYPE user:profile if user:profile is a hash storing user attributes?

Redis

TYPE user:profile

A "hash"

B "string"

C "list"

D "none"

💡 Hint

Hashes store field-value pairs in Redis.

The TYPE command returns "hash" for keys storing hashes.

🧠 Conceptual

expert

Understanding TYPE command behavior with expired keys

If a key temp:data is set with an expiration and expires before the TYPE temp:data command is run, what will the TYPE command return?

A "expired"

B "string"

C "none"

D "error"

💡 Hint

Expired keys are automatically removed from Redis.

Once a key expires, it is deleted and no longer exists, so TYPE returns "none".