How is PATCH related to caching GET (the problem of cache staleness after changes)?

PATCH is an HTTP method for partial updates of a resource. Caching issues with GET requests arise when, after data is modified via PATCH, the cached GET results become outdated.

The relationship is as follows:

• GET requests are often cached to improve performance.
• After data is modified via PATCH, the cache of GET responses may not update automatically.
• This leads to clients receiving stale data from the cache instead of the current data.

To address this issue, the common approaches are:

• Cache invalidation after a successful PATCH request.
• Using Cache-Control and ETag headers to control data freshness.
• In some architectures, sending notifications to clients to refresh their cache.

Thus, PATCH requires additional cache management logic for GET requests to prevent data desynchronization.