Cachelagrer

Cachelagrer is a term used in computing to denote the caching layer within a data architecture. It acts as an intermediary that stores copies of frequently accessed data to reduce latency and relieve load on primary data stores.

A cachelagrer can reside at multiple levels, from hardware CPU caches to application-level caches, and to distributed caches that serve many application instances. In web architectures, it often appears as a proxy or edge cache between clients and backend systems, and it may be implemented as in-memory stores or as persistent but fast-access services.

Core concepts include data expiration, eviction, and invalidation. Data is kept temporarily; a time-to-live (TTL) or max-age governs retention. When cache space is needed, items are removed according to an eviction policy such as least-recently-used (LRU), least-frequently-used (LFU), or FIFO. Cache invalidation ensures consistency with the underlying data source, using approaches like write-through, write-behind, write-around, explicit invalidation on updates, or event-driven signals. Cache warming can preload popular items after deploys or cache clear events.

Trade-offs exist: caches speed up reads and reduce backend pressure but introduce potential data staleness and added complexity. They are most effective for read-heavy workloads with data that does not change extremely rapidly, or where consistency requirements can tolerate eventual updates.

Common implementations include Redis and Memcached for application caches, Varnish or NGINX for HTTP proxies, and CDNs for edge caching. CPU caches (L1/L2/L3) are also forms of a cachelagrer within the processor.

Design considerations involve cache key design, serialization, eviction tuning, TTL configuration, and monitoring of hit rates and latency.