Instant Purge lets you update stale content within 150 milliseconds or less. When you issue a purge request, our servers stop delivering cached versions of that content. Once a visitor to your site requests the purged content, we retrieve an updated copy from your origin server and serve it as soon as it’s live on your web server.
You can trigger Instant Purge using the Fastly Control Panel, or via an HTTP API call. Purging can be done on an individual URL basis, by surrogate key, wildcard, or you can purge your entire site at once.
Traditional CDNs only allow you to purge either individual items or your entire website. Many websites are made up of millions of interrelated objects, making it challenging to update all related content. Fastly’s surrogate keys allow you to fine-tune purging.
With surrogate keys, you can tag related objects across your site with a key name and description and purge by this key. You can purge entire classes or libraries of objects, such as sale items, discontinued products, or outdated news content across your site. Surrogate keys are particularly powerful for larger sites — you can purge a lot of specific items quickly, saving valuable time while avoiding the performance hit from purging the entire cache at once.
Fastly’s Soft Purge feature allows you to mark content as outdated or slightly stale, instead of permanently removing it from cache. This ensures good user experiences even if your origin server goes down or takes longer than usual to update.
Instead of showing an error message, as you would with traditional CDNs, you can configure your content to serve stale-if-error or stale-while-revalidate. With stale-while-revalidate, the first person requesting a page after purging receives slightly outdated content, while your page is being refreshed in the background.