All 15 Caching (In-Memory, Distributed & Redis) questions
More in Caching (In-Memory, Distributed & Redis)
What is IMemoryCache, and when is it appropriate to use for caching in ASP.NET Core? What does the GetOrCreateAsync pattern accomplish when working with IMemoryCache, and why is it preferred over separate TryGetValue/Set calls? How do you configure and use Redis as a distributed cache in ASP.NET Core with StackExchange.Redis? What are common cache invalidation strategies, and why is cache invalidation considered a genuinely hard problem? What is response caching middleware in ASP.NET Core, and how does it differ from application-level data caching? What is cache-aside (lazy loading) pattern, and how does it compare to write-through caching? What HTTP caching headers (Cache-Control, ETag) can a client and CDN use, and how do they relate to server-side caching strategies? What are the risks of caching sensitive or user-specific data, and how do you avoid cache poisoning across users? What is IDistributedCache, and how does it differ from IMemoryCache in a multi-instance deployment? What is the 'cache stampede' (thundering herd) problem, and how can you mitigate it?
Advertisement
Back to results for “Authentication”
.NET › Caching (In-Memory, Distributed & Redis)

What is the difference between absolute expiration and sliding expiration when configuring a cache entry?

Intermediate

Answer

Absolute expiration removes an entry at a fixed point in time regardless of how recently it was accessed, guaranteeing data won't become stale beyond a hard limit. Sliding expiration resets the expiration timer every time the entry is accessed, keeping frequently-used data cached indefinitely while letting rarely-used entries expire -- the two can be combined to set both a 'refresh on access' behavior and a hard maximum lifetime.
_cache.Set("key", value, new MemoryCacheEntryOptions {
    SlidingExpiration = TimeSpan.FromMinutes(5),      // resets on each access
    AbsoluteExpirationRelativeToNow = TimeSpan.FromHours(1)  // hard cap regardless
});
Real-world example A frequently-accessed user session cache uses a 5-minute sliding expiration combined with a 1-hour absolute cap, so active users keep their cached session alive while inactive sessions are forcibly cleared within an hour at most.

Common follow-ups: What happens if only sliding expiration is set with no absolute cap?;How does cache eviction interact with memory pressure signals?

Diagnostics & Performance;Authentication & Authorization (Identity JWT OAuth)
All 15 Caching (In-Memory, Distributed & Redis) questions