I'm working with a legacy codebase for a web app with an architecture that they call "widget based". It's basically cached database result sets of data that is to be presented on several "widgets" in different parts of the application. So, when they update or create a new record, they use a set of rules to know which caches to invalidate so that said record would be presented.
By reading the varnish use case examples, it looks like it's not built to cache database records (like memcache or apc), but a webserver's response itself (AKA, the whole html page).
If my last statement is correct, how can I invalidate only the varnish cache's cache registries for the html pages that shows the new record (basically, cherry-picking what to invalidate)?