When talking about caching, nearly all the attention goes to ensuring that content is properly stored in the cache. While that makes total sense from a performance perspective, people tend to forget that removing objects from the cache is equally as important.

It's cargo-cult fighting time! Today, we are going to look at a ban expression that you probably have used, and maybe even have recommended (gasp!) to your fellow Varnish users:

req.url ~ /

We'll discuss why we use it, why it's good but mostly bad, and how to fix it. Hopefully, along the way, we'll shed some light on some Varnish internals that you can use in other situations.

sheego.de, like most e-commerce platforms, is in a perpetual state of growth. Ensuring this growth requires constant technical improvements to keep boosting performance and stability. sheego.de, a German online fashion clothing mail-order company, which specializes in mail-order fashion for women sized 40 (UK size 16) and up, adopted Varnish Plus as its caching and performance component as it moved to the open-source, PHP-based OXID eShop framework.

Quite a while back, I wrote the first part of this blog series about the challenges of cache invalidation with the dispatcher in Adobe Experience Manager 6.0 and Adobe CQ 5.x in any Linux platform (Adobe supports Red Hat running a Linux Kernel 2.6 and 3.x). So the context should be clear. But how do you actually go about replacing it?