What is the difference between TTL and LRU cache?

TTL (Time To Live) and LRU (Least Recently Used) are different cache management strategies.

• TTL cache stores data with a time-to-live limit. Each item in the cache has a timestamp, and after the specified time (TTL) expires, the item is considered stale and is removed or updated.

• LRU cache removes the least recently used item when the cache reaches its maximum size. This strategy is focused on the frequency and recency of data usage.

Application examples:

• TTL is suitable when data becomes outdated over time (e.g., caching API responses that update every 5 minutes).
• LRU is suitable when it is important to keep the most frequently or recently used data, with a limit on memory volume.

Thus, TTL manages the data's lifetime, while LRU manages the removal order based on usage.