Revalidation

Revalidation refreshes cached data or routes after time intervals, on-demand path invalidation, or cache tags tied to entities. `revalidatePath`, `revalidateTag`, and fetch `next.tags` connect writes to reads.

					import { revalidateTag } from 'next/cache';

export async function updatePost(id: string) {
  await savePost(id);
  revalidateTag('posts');
}
				

Operational triggers include webhooks, admin actions, and deploy pipelines — not only time-based windows.

On interviews: design invalidation for a CMS edit that affects a listing page and detail pages.

Common pitfalls: forgetting to tag fetches, over-broad path revalidation, and no monitoring of stale user reports.

The trade-off is precise invalidation work versus blast-radius of path-based clears.

Checklist:

• Tag fetches that share invalidation scope.
• Revalidate after successful mutations.
• Prefer tags over wiping entire sites.
• Log revalidation in admin workflows.