Refresh-ahead proactively refreshes cache entries before they expire. You avoid cache misses for predictable access patterns.
How it works:
When TTL reaches a threshold (e.g., % expired), background process refreshes the entry. Users always get cached data without waiting for database.
This works well when you can predict which keys will be accessed. Product catalogs with regular traffic patterns benefit from this approach. The trade-off is wasted refreshes for keys that are not accessed again.