Key design patterns in Redis - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the Cache Aside pattern in Redis?

Cache Aside is a design pattern where the application first checks Redis for data. If the data is missing, it loads from the database, stores it in Redis, then returns it. This helps keep Redis as a fast cache.

intermediate

Explain the Rate Limiting pattern using Redis.

Rate Limiting controls how often a user can perform an action. Redis uses counters with expiration to track requests per user, blocking requests that exceed limits within a time window.

beginner

What is the purpose of the Pub/Sub pattern in Redis?

Pub/Sub allows messages to be sent to multiple subscribers instantly. Publishers send messages to channels, and subscribers listening to those channels receive them in real-time.

intermediate

Describe the Leaderboards pattern in Redis.

Leaderboards use Redis sorted sets to keep scores ranked. Scores can be updated quickly, and top players retrieved efficiently, making it ideal for games or competitions.

advanced

How does the Distributed Lock pattern work in Redis?

Distributed Lock uses Redis keys with expiration to ensure only one process can access a resource at a time. It prevents conflicts in distributed systems by locking critical sections.

Which Redis data structure is best for implementing a leaderboard?

A Lists

B Hashes

C Sorted Sets

D Strings

Sorted Sets store members with scores and keep them ordered, perfect for leaderboards.

In the Cache Aside pattern, what happens if data is not found in Redis?

A Return an error immediately

B Delete the Redis cache

C Ignore the request

D Load data from the database, store it in Redis, then return it

The application loads data from the database, caches it in Redis, then returns it.

What does the Rate Limiting pattern in Redis typically use to track requests?

A Strings with expiration

B Counters with expiration

C Lists

D Hashes

Counters with expiration track how many requests a user makes in a time window.

What is the main benefit of using the Pub/Sub pattern in Redis?

A Real-time message delivery to multiple subscribers

B Sorting data

C Data backup

D Storing large files

Pub/Sub delivers messages instantly to all subscribers listening on a channel.

How does Redis help implement a Distributed Lock?

A By using keys with expiration to lock resources

B By storing user sessions

C By caching database queries

D By sorting data

Keys with expiration ensure only one process holds the lock at a time.

Describe how the Cache Aside pattern works in Redis and why it is useful.

Think about how Redis acts as a fast storage layer before the database.

Explain how Redis can be used to implement rate limiting for user requests.

Consider how Redis counters and expiration help track request frequency.

Practice

1. What is the main purpose of using key design patterns in Redis?

easy

A. To delete all keys automatically

B. To organize data for easy access and management

C. To slow down data retrieval

D. To increase the size of the database

Solution

1. Step 1: Understand Redis key design patterns

   Key design patterns help organize Redis keys logically.

2. Step 2: Identify the main benefit

   Organizing keys makes data easier to access and manage efficiently.

3. Final Answer:

   To organize data for easy access and management -> Option B

4. Quick Check:

   Key design patterns = organize data [OK]

Hint: Think about why organization helps in real life [OK]

Common Mistakes:

• Confusing organization with database size
• Assuming patterns slow down Redis
• Thinking patterns delete keys automatically

2. Which of the following is a correct Redis key pattern to group user data by user ID?

easy

A. user:1234:name

B. user-1234-name

C. user1234name

D. user/1234/name

Solution

1. Step 1: Identify common Redis key pattern syntax

   Redis keys often use colons ':' as separators for readability and grouping.

2. Step 2: Compare options

   user:1234:name uses colons to separate user, ID, and attribute clearly.

3. Final Answer:

   user:1234:name -> Option A

4. Quick Check:

   Colon separators = correct pattern [OK]

Hint: Use colons to separate parts of keys [OK]

Common Mistakes:

• Using dashes or slashes which are less common
• Not separating parts clearly
• Combining all parts without separators

3. Given these Redis keys: order:1001:status, order:1002:status, and order:1001:items, which command retrieves the status of order 1002?

medium

A. GET order:1001:items

B. GET order:1002:items

C. GET order:1002:status

D. GET order:1001:status

Solution

1. Step 1: Identify the key for order 1002 status

   The key format is order:<order_id>:status, so for 1002 it is order:1002:status.

2. Step 2: Match the command to the key

   GET order:1002:status retrieves the status of order 1002.

3. Final Answer:

   GET order:1002:status -> Option C

4. Quick Check:

   Correct key = order:1002:status [OK]

Hint: Match key parts exactly to get correct data [OK]

Common Mistakes:

• Mixing order IDs in keys
• Using wrong attribute like items instead of status
• Confusing similar keys

4. You have keys like session-123 and session:124. Why might this inconsistency cause problems?

medium

A. Redis will merge both keys automatically

B. Redis will throw a syntax error

C. Keys with dashes are not allowed in Redis

D. It breaks pattern consistency, making data harder to manage

Solution

1. Step 1: Understand key pattern consistency

   Consistent key patterns help group and find related data easily.

2. Step 2: Analyze the impact of mixed separators

   Using both dashes and colons breaks this consistency, causing confusion.

3. Final Answer:

   It breaks pattern consistency, making data harder to manage -> Option D

4. Quick Check:

   Inconsistent keys = management issues [OK]

Hint: Always use one separator style consistently [OK]

Common Mistakes:

• Thinking Redis forbids dashes
• Expecting syntax errors from mixed separators
• Assuming Redis merges keys automatically

5. You want to store product reviews in Redis for multiple products and users. Which key design pattern is best to efficiently group reviews by product and user?

hard

A. review:<product_id>:<user_id>

B. <product_id>-review-<user_id>

C. review<product_id><user_id>

D. review/<product_id>/<user_id>

Solution

1. Step 1: Identify clear, scalable key pattern

   Using colons to separate product and user IDs groups reviews logically.

2. Step 2: Evaluate options for clarity and consistency

   review:<product_id>:<user_id> uses colons and a prefix 'review' for easy filtering and management.

3. Final Answer:

   review:<product_id>:<user_id> -> Option A

4. Quick Check:

   Colon-separated keys = best practice [OK]

Hint: Use prefixes and colons to group related data [OK]

Common Mistakes:

• Using ambiguous separators like dashes or slashes
• Combining parts without separators
• Not using a clear prefix for grouping