How does cache expiration work?
(e.g., time-based, size-based eviction policies)
How does cache expiration work?
Ask by Anubhav Sharma
Updated 07 Apr 2025
The technique of Cache expiration determines the duration data remains inside the cache until it is deemed outdated. The management of updated cache data with source content, together with efficient memory resource management, makes this technique effective.
Two essential methods exist to manage cache expiration.
Time-based expiration (TTL – Time To Live)
When using this approach, users retain items with a preset expiration limit. The system assigns a TTL value at the time of adding an item to the cache, with 10 minutes being an example period. After the specified duration expires, the cache system automatically deletes data even though it remains unused. The TTL system enables web browsers and CDN caches, and DNS caching to determine when fresh resources must be obtained due to stored resource expiration limits.
Access-based expiration (LRU – Least Recently Used)
Access pattern records help some storage systems decide when data should become obsolete. LRU caching has a mechanism for removing unused items first from the full cache. The expiration method avoids using time because it focuses on both data usage frequency and recency. The data caching system maintains the most useful data points in its active cache area.
Manual or event-based invalidation provides a method to delete cached data when particular trigger events take place
(for example, updates to database records).The appropriate implementation of cache expiration allows users to access modern data, combined with performance benefits. The absence of proper cache expiration methods would force caches to display out-of-date information, thus causing data inconsistencies. Developers need to select expiration techniques according to their specific use case to achieve ideal speed and freshness, together with optimal resource utilization.