HSET and HGET for fields in Redis - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the Redis command HSET do?

HSET sets the value of a field in a hash stored at a key. If the field does not exist, it is created. If it exists, the value is updated.

beginner

How do you retrieve the value of a specific field in a Redis hash?

You use the HGET command with the key and the field name to get the value stored in that field.

beginner

What will HGET return if the field does not exist in the hash?

HGET returns null (or nil) if the specified field is not found in the hash.

intermediate

Can HSET create a new hash if the key does not exist?

Yes, if the key does not exist, HSET will create a new hash and then set the field with the given value.

intermediate

What is the difference between HSET and SET in Redis?

SET stores a simple string value at a key. HSET stores a field-value pair inside a hash at a key, allowing multiple fields under one key.

What does the Redis command HGET myhash field1 return if field1 exists?

A The key <code>myhash</code>

B The value stored in <code>field1</code> inside <code>myhash</code>

C An error message

D The entire hash <code>myhash</code>

HGET returns the value of the specified field inside the hash.

If you run HSET myhash field1 "hello" and field1 already has a value, what happens?

A The value of <code>field1</code> is updated to "hello"

B A new field is created

C An error is thrown

D Nothing changes

HSET updates the value if the field exists.

What does HGET return if the field does not exist in the hash?

A An empty string

B 0

C The entire hash

D null (nil)

HGET returns null (nil) if the field is missing.

Which command creates a new hash if the key does not exist?

A HSET

B HGET

C GET

D DEL

HSET creates the hash if it does not exist.

Which Redis command stores a simple string value at a key?

A HGET

B HSET

C SET

D HMSET

SET stores a string value at a key.

Explain how HSET and HGET work together to store and retrieve data in Redis hashes.

Think about how you store and look up information in a dictionary.

Describe the difference between using SET and HSET in Redis.

Compare storing one item versus storing a collection of items.