HGETALL for all fields in Redis - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the Redis command HGETALL do?

It retrieves all fields and their values from a hash stored at a given key.

beginner

How is the output of HGETALL structured?

It returns a list of fields and values alternating, like [field1, value1, field2, value2, ...].

beginner

If a hash key does not exist, what does HGETALL return?

It returns an empty list because there are no fields or values to show.

beginner

Can HGETALL be used to get a single field's value?

No, HGETALL returns all fields and values. Use HGET for a single field.

intermediate

Why might you prefer HGETALL over multiple HGET commands?

Because HGETALL fetches all data in one command, reducing network calls and improving speed.

What type of Redis data structure does HGETALL work with?

A Hash

B List

C Set

D String

HGETALL is used to get all fields and values from a hash.

What does HGETALL myhash return if myhash contains {"name":"Alice", "age":"30"}?

A ["Alice", "name", "30", "age"]

B ["name", "age"]

C ["name", "Alice", "age", "30"]

D ["Alice", "30"]

The output lists fields and values alternating: field1, value1, field2, value2.

If the key does not exist, what does HGETALL return?

A A list with one empty string

B Null

C An error

D An empty list

HGETALL returns an empty list if the hash key is missing.

Which command should you use to get only one field's value from a hash?

A HGET

B HMGET

C GET

D HGETALL

HGET retrieves the value of a single field from a hash.

Why is HGETALL efficient when you need all fields?

A It uses less memory

B It sends one command instead of many

C It compresses data

D It caches results automatically

HGETALL reduces network calls by fetching all fields and values in one command.

Explain what the Redis command HGETALL does and describe its output format.

Think about how a hash stores data as field-value pairs.

When would you use HGETALL instead of multiple HGET commands? Explain why.

Consider the cost of sending many commands versus one.