Cache Smart: Database Query Caching Strategies Quiz Quiz

1. Suitable Cache Use Case

   Which scenario is best suited for using a cache to store database query results?

   1. Querying frequently accessed but rarely changing data
   2. Querying data that changes every few milliseconds
   3. Running write-heavy transactions
   4. Backing up the entire database regularly
   5. Using cache for handling user authentication tokens

2. Cache Strategy Choice

   Given that your user profile data changes occasionally but is queried often, which caching strategy is most appropriate?

   1. Read-through caching
   2. Write-back caching
   3. Cache-busting
   4. No caching at all
   5. Full-database replication

3. Cache Expiration Policy

   What is the main reason to set an expiration time (TTL) on cached query results?

   1. To ensure stale data doesn't remain in cache indefinitely
   2. To save memory on the disk
   3. To improve the syntax of SQL queries
   4. To allow database normalization
   5. To prevent SQL injection attacks

4. Cache Invalidation

   When should you invalidate/evict a cached item for a SELECT query on a products table?

   1. Whenever the corresponding product is updated or deleted
   2. At a random time
   3. Only when a user logs out
   4. After every database connection
   5. After every server restart regardless of data

5. Query Result Uniqueness

   Why is it important to include query parameters (such as filters or pagination) in your cache key?

   1. So each unique query result is properly cached and retrievable
   2. To increase memory usage unnecessarily
   3. Because SQL requires unique cache keys
   4. To allow for LRU cache eviction policy
   5. To enable transaction rollback

6. Code Snippet Analysis

   Given the following code snippet, what is the main issue?nncache.set('users', results)n# Later...ncached = cache.get('users?name=alice')nn

   1. The cache key does not include the query parameters, causing potential data mismatch
   2. The cache object is not thread-safe
   3. No cache timeout has been set
   4. The code exposes cache to SQL injection
   5. Cache should use read-through, not manual set/get

7. Cache Write Strategy

   Which of the following describes write-through caching in the context of a database?

   1. Every write updates both the cache and the database immediately
   2. Every write only updates the cache, not the database
   3. Writes update the database but not the cache
   4. Cache updates are deferred until eviction
   5. Data is always written asynchronously to the cache

8. Distributed Cache Consistency

   In a distributed cache system, what is a common challenge when caching query results?

   1. Keeping cached data consistent across multiple nodes
   2. Not enough RAM on a single server
   3. Needing to normalize database tables
   4. Ensuring database schema migrations occur
   5. Caching only works with SQL databases

9. Avoiding Cache Stampede

   What is a ‘cache stampede’ in database caching strategies, and how can it be avoided?

   1. When many clients simultaneously try to refresh an expired cache entry; use locking or request coalescing to prevent it
   2. A typo in the cache key format; you fix it by spellchecking
   3. When cache servers run out of storage space; use SSD caching
   4. When a network outage deletes all cache data; add more cables
   5. When cache TTLs are too long; reduce TTL duration

10. Selecting a Cache When Data is Volatile

    If a dataset changes very frequently and consistency is critical, what is the most appropriate caching strategy for query results?

    1. Avoid caching or use a very short TTL
    2. Cache with a long expiration time
    3. Never invalidate cache entries
    4. Store all dataset copies in cache permanently
    5. Only cache on the client-side