Caching strategies in Supabase - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set a cache expiration time of 60 seconds.

Supabase

const { data, error } = await supabase.from('items').select('*').cache({ ttl: [1] });

Drag options to blanks, or click blank then click option'

A60

B0

C120

D30

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 disables caching instead of setting expiration.

Choosing a very high number causes stale data.

Setting ttl to 60 means the cache will expire after 60 seconds.

2fill in blank

medium

Complete the code to enable cache for the query.

Supabase

const { data, error } = await supabase.from('users').select('*').[1]();

Drag options to blanks, or click blank then click option'

AnoCache

Bcache

CdisableCache

DclearCache

Attempts:

3 left

💡 Hint

Common Mistakes

Using noCache() disables caching.

Using clearCache() removes cached data.

The cache() method enables caching for the query.

3fill in blank

hard

Fix the error in the cache invalidation code.

Supabase

await supabase.cache.[1]('users');

Drag options to blanks, or click blank then click option'

AclearCache

BrefreshCache

CinvalidateCache

DresetCache

Attempts:

3 left

💡 Hint

Common Mistakes

Using clearCache is not a valid method.

Using refreshCache does not exist in Supabase.

The correct method to invalidate cache for a table is invalidateCache.

4fill in blank

hard

Fill both blanks to create a cache with a 5-minute expiration and force refresh.

Supabase

const { data, error } = await supabase.from('products').select('*').cache({ ttl: [1], forceRefresh: [2] });

Drag options to blanks, or click blank then click option'

A300

Btrue

Cfalse

D60

Attempts:

3 left

💡 Hint

Common Mistakes

Using 60 seconds instead of 300 for 5 minutes.

Setting forceRefresh to false does not force reload.

TTL of 300 seconds equals 5 minutes. Setting forceRefresh to true forces fresh data.

5fill in blank

hard

Fill all three blanks to cache a query with a 10-minute TTL, disable force refresh, and specify a cache key.

Supabase

const { data, error } = await supabase.from('orders').select('*').cache({ ttl: [1], forceRefresh: [2], key: '[3]' });

Drag options to blanks, or click blank then click option'

A600

Bfalse

Corders_cache

Dtrue

Attempts:

3 left

💡 Hint

Common Mistakes

Using true for forceRefresh when disabling is needed.

Using a numeric value instead of a string for the cache key.

TTL 600 seconds equals 10 minutes. forceRefresh false disables forced reload. The cache key is a string identifier.

Practice

1. What is the main purpose of caching in Supabase applications?

easy

A. To store data temporarily and speed up data access

B. To permanently save all user data

C. To delete old data from the database

D. To encrypt data for security

Solution

1. Step 1: Understand caching basics

   Caching temporarily stores data to avoid repeated database calls.

2. Step 2: Identify caching purpose in Supabase

   It speeds up app performance by quickly providing stored data.

3. Final Answer:

   To store data temporarily and speed up data access -> Option A

4. Quick Check:

   Caching = Temporary storage for speed [OK]

Hint: Caching means temporary storage to speed up access [OK]

Common Mistakes:

• Thinking caching permanently saves data
• Confusing caching with encryption
• Believing caching deletes data

2. Which of the following is the correct way to set a cache TTL (time-to-live) in Supabase client code?

easy

A. cache.set('key', value, { ttl: 300 })

B. cache.set('key', value, ttl=300)

C. cache.set('key', value, timeout: 300)

D. cache.set('key', value, expire: 300)

Solution

1. Step 1: Review Supabase cache TTL syntax

   Supabase uses an options object with a ttl property to set time-to-live.

2. Step 2: Match correct syntax

   cache.set('key', value, { ttl: 300 }) uses { ttl: 300 } which is the correct way to specify TTL in seconds.

3. Final Answer:

   cache.set('key', value, { ttl: 300 }) -> Option A

4. Quick Check:

   TTL set with { ttl: seconds } object [OK]

Hint: TTL uses { ttl: seconds } object in cache.set [OK]

Common Mistakes:

• Using ttl=300 instead of { ttl: 300 }
• Using wrong property names like timeout or expire
• Passing TTL as a separate argument without object

3. Given this Supabase cache check code:

const cachedData = cache.get('user_123');
if (cachedData) {
  console.log('Cache hit:', cachedData);
} else {
  const data = await supabase.from('users').select('*').eq('id', 123);
  cache.set('user_123', data, { ttl: 600 });
  console.log('Cache miss, fetched:', data);
}

What will be logged if the cache already has data for 'user_123'?

medium

A. Cache miss, fetched: [new data]

B. Cache hit: [cached data]

C. Error: cache.get is not a function

D. No output

Solution

1. Step 1: Check cache.get return value

   If cache has data for 'user_123', cachedData is truthy.

2. Step 2: Follow code logic on cache hit

   Code logs 'Cache hit:' plus cachedData without fetching from database.

3. Final Answer:

   Cache hit: [cached data] -> Option B

4. Quick Check:

   Cache hit logs cached data [OK]

Hint: Cache hit means cachedData exists, logs cache hit [OK]

Common Mistakes:

• Assuming it fetches from database even if cache exists
• Confusing cache miss and hit outputs
• Expecting errors when cache is valid

4. You wrote this code to cache user data but it always fetches from the database:

const cached = cache.get('user_1');
if (!cached) {
  const data = await supabase.from('users').select('*').eq('id', 1);
  cache.set('user_1', data, { ttl: 300 });
}
console.log(cached);

What is the main issue causing the cache miss?

medium

A. TTL is too short to keep data

B. cache.get syntax is incorrect

C. You never update the cached variable after setting cache

D. Database query is wrong

Solution

1. Step 1: Analyze variable assignment

   Variable 'cached' is assigned once before cache.set, so it stays null.

2. Step 2: Understand cache update logic

   After setting cache, 'cached' is not updated to new data, so console.log shows null.

3. Final Answer:

   You never update the cached variable after setting cache -> Option C

4. Quick Check:

   cached variable must update after cache.set [OK]

Hint: Update cached variable after cache.set to avoid misses [OK]

Common Mistakes:

• Assuming cache.set updates cached variable automatically
• Blaming TTL without checking variable assignment
• Thinking cache.get syntax is wrong without error

5. You want to optimize a Supabase app by caching user profile data but ensure updates are reflected quickly. Which caching strategy is best?

hard

A. Cache data without TTL and manually clear cache daily

B. Use very long TTL (e.g., 24 hours) to minimize database calls

C. Never cache user profiles to avoid stale data

D. Use short TTL (e.g., 60 seconds) and refresh cache after updates

Solution

1. Step 1: Consider update frequency and freshness

   User profiles may change, so cache must refresh often to avoid stale data.

2. Step 2: Choose caching strategy balancing speed and freshness

   Short TTL with cache refresh after updates keeps data fresh and speeds access.

3. Final Answer:

   Use short TTL (e.g., 60 seconds) and refresh cache after updates -> Option D

4. Quick Check:

   Short TTL + refresh = fresh and fast cache [OK]

Hint: Short TTL plus refresh keeps cache fresh and fast [OK]

Common Mistakes:

• Using long TTL causing stale data
• Avoiding cache entirely losing speed benefits
• Not refreshing cache after updates