KEYS pattern matching (avoid in production) in Redis - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the Redis KEYS command do?

The KEYS command finds all keys in the database that match a given pattern.

beginner

Why should you avoid using KEYS in production?

Because KEYS scans the entire database, it can slow down Redis and block other commands, especially with many keys.

intermediate

What is a safer alternative to KEYS for pattern matching in Redis?

Use the SCAN command, which iterates over keys incrementally without blocking Redis.

beginner

Give an example pattern you might use with KEYS.

For example, KEYS user:* finds all keys starting with user:.

intermediate

What kind of patterns can KEYS match?

It supports glob-style patterns like * (any characters), ? (single character), and [abc] (character sets).

What does the Redis KEYS command return?

A All keys matching a pattern

B The value of a key

C The number of keys in the database

D The type of a key

KEYS returns all keys matching the given pattern.

Why is KEYS not recommended in production?

A It deletes keys

B It blocks Redis and slows performance

C It only works on small databases

D It returns incorrect results

KEYS scans all keys at once, which can block Redis and slow down performance.

Which command is better for safely scanning keys in Redis?

A SCAN

B SET

C GET

D DEL

SCAN iterates keys incrementally without blocking Redis.

What pattern would find all keys starting with 'session:'?

A session[]

B session?

C *session

D session:*

The pattern session:* matches keys starting with 'session:'.

Which wildcard matches exactly one character in Redis patterns?

A *

B #

C ?

D [abc]

The ? wildcard matches exactly one character.

Explain what the Redis KEYS command does and why it should be avoided in production.

Think about how scanning all keys affects Redis performance.

Describe the difference between KEYS and SCAN commands in Redis.

Consider how each command handles large numbers of keys.