Designing cache tags before you need to purge

Designing cache tags before you need to purge

An online magazine in Cape Town could only purge by exact URL. When an author's name changed, they manually purged 140 article URLs by hand and missed a dozen.

We designed a cache-tag architecture up front:

— Tagged every response with multiple tags: post-{id}, author-{id}, section-{id}, global-nav
— A post edit purged post-id; an author change purged author-id — every page they touch, in one call
— A nav change purged global-nav across the whole site instantly
— Kept tags under the provider's per-response limit by being deliberate, not tagging everything
— Logged every purge with its tag for an audit trail

The author-rename that used to take 30 manual minutes and missed pages became one author-42 purge that cleared all 152 affected pages atomically. Design tags at write time around how you'll need to invalidate — retrofitting tags onto a live site is painful.

The number that mattered: 152 pages purged correctly with a single tag call.