Cache management in GraphQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is cache management in GraphQL?

Cache management in GraphQL is the process of storing and updating query results locally to reduce server requests and improve app speed.

beginner

Why is cache management important in GraphQL?

It helps apps load data faster, reduces network use, and improves user experience by showing data quickly even when offline.

intermediate

What is a cache key in GraphQL caching?

A cache key is a unique identifier for stored data, often based on query and variables, so the cache knows what data to return.

intermediate

How does cache invalidation work in GraphQL?

Cache invalidation means removing or updating cached data when it changes on the server, so the app shows fresh information.

intermediate

Name one common strategy for cache management in GraphQL clients.

One common strategy is 'normalized caching', where data is stored by unique IDs to update parts of the cache efficiently.

What does cache management primarily help with in GraphQL apps?

A Increasing server load

B Reducing server requests and speeding up data loading

C Deleting all data permanently

D Changing the GraphQL schema

Cache management stores data locally to reduce server requests and speed up loading.

What is a cache key used for in GraphQL caching?

A To create new queries

B To encrypt data

C To uniquely identify cached data

D To delete the server

Cache keys uniquely identify cached data so the system knows what to return.

Which of these is a cache invalidation method?

A Deleting the entire database

B Ignoring server updates

C Storing data forever without changes

D Updating cached data when server data changes

Cache invalidation updates or removes cached data when the server data changes.

Normalized caching means:

A Storing data by unique IDs for efficient updates

B Storing data as one big block

C Not using any cache

D Caching only images

Normalized caching stores data by unique IDs to update parts of the cache easily.

What happens if cache is not managed properly?

A App may show outdated data or slow down

B App will always be faster

C Server will stop working

D Data will be deleted automatically

Poor cache management can cause outdated data display or slow app performance.

Explain what cache management is and why it matters in GraphQL applications.

Think about how apps load data faster and use less network.

Describe how cache invalidation works and why it is necessary.

Consider what happens if cached data is old.

Practice

1. What is the main purpose of cache management in GraphQL?

easy

A. To temporarily store data for faster repeated requests

B. To permanently save all data in the database

C. To delete all data after each request

D. To encrypt data for security

Solution

1. Step 1: Understand cache management purpose

   Cache management is used to store data temporarily to speed up access.

2. Step 2: Compare options with cache purpose

   Only To temporarily store data for faster repeated requests matches the temporary storage for faster repeated requests.

3. Final Answer:

   To temporarily store data for faster repeated requests -> Option A

4. Quick Check:

   Cache speeds up repeated requests = A [OK]

Hint: Cache means temporary storage for speed [OK]

Common Mistakes:

• Thinking cache stores data permanently
• Confusing cache with encryption
• Assuming cache deletes data immediately

2. Which of the following is the correct way to specify a cache key argument in a GraphQL query?

easy

A. query { user(id: 1) @cacheKey(key: "id") { name }

B. query { user(id: 1) @cache(key: "id") { name }

C. query { user(id: 1) @cacheKey(id) { name }

D. query { user(id: 1) @cacheKey(key: id) { name }

Solution

1. Step 1: Identify correct syntax for cache key argument

   The cache key argument uses @cacheKey with a key string in quotes.

2. Step 2: Check each option's syntax

   query { user(id: 1) @cacheKey(key: "id") { name } correctly uses @cacheKey(key: "id") with quotes around key name.

3. Final Answer:

   query { user(id: 1) @cacheKey(key: "id") { name } -> Option A

4. Quick Check:

   Cache key argument needs quotes = A [OK]

Hint: Cache keys need quotes around key name [OK]

Common Mistakes:

• Omitting quotes around key name
• Using wrong directive name like @cache
• Passing key without key: label

3. Given the following GraphQL query with cache expiry set to 60 seconds:

query { product(id: 5) @cacheControl(maxAge: 60) { name price } }

What happens if you request the same product again within 30 seconds?

medium

A. An error occurs due to cache expiry mismatch

B. The server fetches fresh data ignoring the cache

C. The cache is cleared and data is refetched

D. The cached data is returned without fetching from the server

Solution

1. Step 1: Understand maxAge cache expiry

   maxAge: 60 means cache is valid for 60 seconds after storing data.

2. Step 2: Check request timing

   Request within 30 seconds is before expiry, so cached data is used.

3. Final Answer:

   The cached data is returned without fetching from the server -> Option D

4. Quick Check:

   Request before maxAge returns cache = C [OK]

Hint: Cache valid until maxAge seconds pass [OK]

Common Mistakes:

• Assuming cache expires immediately
• Thinking server always refetches
• Confusing maxAge with minimum age

4. Identify the error in this GraphQL cache directive usage:

query { user(id: 10) @cacheControl(maxAge: "thirty") { name email } }

medium

A. The directive name should be @cacheKey, not @cacheControl

B. The user id must be a string, not a number

C. maxAge value must be a number, not a string

D. The query is missing a required fragment

Solution

1. Step 1: Check maxAge argument type

   maxAge expects a numeric value representing seconds, not a string.

2. Step 2: Analyze the given value

   "thirty" is a string, causing a type error in cacheControl directive.

3. Final Answer:

   maxAge value must be a number, not a string -> Option C

4. Quick Check:

   maxAge needs number, not string = B [OK]

Hint: maxAge must be numeric, no quotes [OK]

Common Mistakes:

• Using string instead of number for maxAge
• Confusing directive names
• Assuming id type causes cache error

5. You want to cache a list of posts but ensure that each post is cached separately by its unique ID. Which cache management strategy should you use in your GraphQL schema?

hard

A. Cache the entire posts list as one entry without keys

B. Use a cache key argument with the post ID to store each post individually

C. Disable caching for posts to always fetch fresh data

D. Set a global cache expiry time for all posts together

Solution

1. Step 1: Understand caching by unique keys

   Caching each post separately requires using a cache key based on post ID.

2. Step 2: Evaluate options for separate caching

   Only Use a cache key argument with the post ID to store each post individually uses cache key argument to store posts individually by ID.

3. Final Answer:

   Use a cache key argument with the post ID to store each post individually -> Option B

4. Quick Check:

   Cache by unique ID key = D [OK]

Hint: Cache items individually using unique keys [OK]

Common Mistakes:

• Caching entire list as one entry
• Relying only on global expiry without keys
• Disabling cache unnecessarily