Cache invalidation strategies in Redis - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set a cache key with an expiration time in Redis.

Redis

redis.set('user:123', 'data', [1]=3600)

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

Aex

Bexpire

Ctimeout

Dttl

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'expire' which is a separate command, not a parameter here.

Using 'ttl' which returns time to live, not sets it.

The ex parameter sets the expiration time in seconds when setting a key in Redis.

2fill in blank

medium

Complete the code to delete a cache key in Redis.

Redis

redis.[1]('user:123')

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

Aremove

Bdel

Cdelete

Dunset

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'del' which is the Redis protocol command but not the Python client method.

Using 'remove' or 'unset' which are not Redis client methods.

The Redis Python client method to delete a key is delete.

3fill in blank

hard

Fix the error in the code to check if a cache key exists in Redis.

Redis

exists = redis.[1]('user:123')

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

Ahas

Bexists

Ccontains

Dcheck

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'has' or 'contains' which are not Redis commands.

Using 'check' which is not a Redis command.

The Redis command to check if a key exists is exists.

4fill in blank

hard

Fill both blanks to set a cache key with a value and expiration time using Redis pipeline.

Redis

pipe = redis.pipeline()
pipe.set('session:[1]', '[2]')
pipe.expire('session:123', 1800)
pipe.execute()

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

A123

Bactive

Cuser

Dinactive

Attempts:

3 left

💡 Hint

Common Mistakes

Mismatching key suffix and expire key.

Using 'inactive' instead of 'active' for session state.

The key suffix is '123' and the value is 'active' to represent an active session.

5fill in blank

hard

Fill all three blanks to implement a cache invalidation strategy that deletes a key and logs the action.

Redis

def invalidate_cache(redis, key):
    redis.[1](key)
    log_message = f"Cache key [2] invalidated at [3]"
    print(log_message)

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

Adel

Bkey

Cdatetime.now()

Ddelete

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'del' instead of 'delete' for Redis client method.

Not using the key variable in the log message.

Not including current time in the log.

The delete method deletes the key, key is the variable name, and datetime.now() gets the current time for logging.