Cache-aside (lazy loading) deep dive in Redis - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to fetch data from cache or load from database if missing.

Redis

value = redis_client.get([1])
if value is None:
    value = db_load(key)
    redis_client.set(key, value)

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

Akey

B'key'

Cvalue

DNone

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string literal instead of the variable key.

The cache key variable should be passed to get to fetch the cached value.

2fill in blank

medium

Complete the code to set the cache expiration time after loading from database.

Redis

if value is None:
    value = db_load(key)
    redis_client.set(key, value, [1]=3600)

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

Attl

Bex

Ctimeout

Dexpire

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect parameter names like 'timeout' or 'ttl'.

Redis set method uses ex to set expiration time in seconds.

3fill in blank

hard

Fix the error in the cache-aside pattern code to avoid race conditions.

Redis

value = redis_client.get(key)
if value is None:
    [1]
    redis_client.set(key, value, ex=3600)

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

Avalue = None

Bvalue = redis_client.get(key)

Cvalue = db_load(key)

Dvalue = cache_load(key)

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to get from cache again inside the miss block.

When cache miss happens, load data from the database to avoid race conditions.

4fill in blank

hard

Fill both blanks to implement cache-aside with explicit cache invalidation.

Redis

def update_data(key, new_value):
    db_update(key, new_value)
    redis_client.[1](key)
    redis_client.[2](key, new_value, ex=3600)

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

Adelete

Bset

Cdel

Dexpire

Attempts:

3 left

💡 Hint

Common Mistakes

Using del which is not a Redis client method.

Use delete to remove old cache, then set to update cache with new value.

5fill in blank

hard

Fill all three blanks to implement cache-aside with fallback and expiration.

Redis

def get_data(key):
    value = redis_client.[1](key)
    if value is None:
        value = db_load([2])
        redis_client.[3](key, value, ex=3600)
    return value

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

Aget

Bkey

Cset

Dload

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong method names like 'load' or wrong variable names.

Use get to fetch from cache, key to load from DB, and set to cache the value.