Caching Strategies — Series 2

Preview — 3 of 10 questions

Compare read-through caching with the cache-aside pattern (where the application itself checks the cache, then falls back to the database on a miss).

ARead-through caching is identical to cache-aside — the terms are simply synonyms used by different vendors

BIn read-through caching, the cache library/layer itself is responsible for loading data from the database on a miss and populating itself — the application only ever talks to the cache, never directly to the database for reads. In cache-aside, the application explicitly manages both the cache lookup and the database fallback logic itself

CRead-through caching means the cache is read once at server startup and never updated again

DRead-through caching can only be implemented with a relational database as the backing store

Before a big product launch, an engineering team pre-loads the cache with expected hot data ahead of time, instead of letting it fill up naturally from real traffic. What is this technique called, and why do it?

AThis is called "cache warming" — proactively populating the cache with anticipated hot keys before traffic arrives, so the very first real requests hit a warm cache instead of all triggering cold cache misses (and hammering the database) simultaneously

BThis technique is called "cache cooling," and it's done to intentionally slow down response times before a launch

CPre-loading a cache before traffic arrives is impossible — caches can only be populated reactively, in response to real requests

DThis is a form of database sharding, unrelated to caching

A lookup service frequently receives requests for IDs that dont exist, and each of those misses triggers a full, expensive database query that finds nothing. Whats negative caching, and how does it help here?

ANegative caching means storing only failed HTTP requests for later retry, unrelated to lookup results

BNegative caching means the cache automatically deletes any entry marked as "negative" or "invalid" after every write

CNegative caching means also caching the absence of a result (e.g., "ID 12345 does not exist") for a short TTL — so repeated lookups for the same non-existent ID hit the cache and return "not found" quickly, instead of re-running the same expensive, always-empty database query every single time

DNegative caching is a synonym for cache eviction — removing old entries to make room for new ones

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