Managing Cache Tag Conflicts
Cache Tag Prefix conflicts can pop up when you have multiple instances of the same web application with LSCache plugins enabled and using the same cache root (as in a WordPress site at /public_html/
and another one at /public_html/wp2/
).
Note: This is not relevant for a single multi-site WordPress install.
The Problem
The cache tag is the same across all instances of a particular app. In each single-site install of Wordpress, for example, it's always b1_
. The cache tag is used to group together pages from the app. As such, it is in control of which pages are purged from cache.
Example: One WordPress installation at www.example.com/
and another WordPress installation at www.example.com/store/
.
In a situation where you might want to purge your entire Example Blog from cache, LSCache interprets the command as “purge everything with the cache tag b1_
” and out goes your entire Example Blog cache and your Example Store cache as well, because it also has the b1_
tag.
The Solution
To differentiate pages of one instance of the app from the pages of another within the cache, you can give each installation its own unique Cache Tag Prefix.