Read-Through

1. The Pattern

The application only ever talks to the cache. On a miss, the cache itself fetches the data from the database, stores a copy, and returns it. The fetching logic lives in one place: inside the cache layer, not scattered through your code.

Recall how cache-aside ended: check-fetch-set-return boilerplate in every data-access function, and a bug class created by write paths that forget their chores. Read-through is that lesson's helper function, promoted to a pattern. The application asks the cache, always