<b>This week in caching: edge vs origin, and the soft purge in between</b>

<b>This week in caching: edge vs origin, and the soft purge in between</b>
Three pieces on where to invalidate.
— <b>soft purge beats hard purge</b> — Fastly's soft purge marks objects stale (serve-stale-while-revalidate) instead of evicting; no origin spike on a flush of 100k URLs.
— <b>surrogate keys / cache tags</b> — tag objects with product-IDs so one event invalidates exactly the affected pages, not the whole site. Fastly surrogate keys, Cloudflare cache-tags (Enterprise).
— <b>two-tier caching</b> — edge for geography, a shielding origin-shield node to protect your backend from edge-PoP misses.
<b>Bookmark:</b> Fastly's surrogate-keys guide — tag-based invalidation is the single biggest upgrade most setups are missing.