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 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.
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.