How does the Savvii cache work?
All websites at Savvii use Varnish caching by default. This is a layer over all websites that remembers the most requested pages in ready-made format, so that they do not have to be rebuilt every time. Certain pages - such as pages with dynamic content - can be difficult to cache. It is advisable to exclude them from caching.
The cache also doesn't work if you are logged in, or if you are using site sessions. These sessions can be recognized by the PHPSESSID cookies.
Your caching doesn't seem to do anything, is that correct?
It can be, and there can be several reasons for it. For example, it is possible that you have a plugin or theme that disables the cache, without notifying you. You can check this by looking at the response header. You can find it via the Developer Tools (F12 in Chrome and Firefox). When you click on the Network tab on the first request made to build your site, you can see the response headers. The Cache-Control header is important. Is there anything there that looks like no-store or no-cache? Then the cache doesn't work.
Do you see in this first request a cookie with a name similar to PHPSESSID? Then there is a plugin that sets a session. This solution also works for a plugin or theme that disables your cache.
When do I have to flush the cache myself?
Sometimes you have to tell the Varnish cache to rebuild it. For most actions, such as (re)publishing pages, the cache is automatically flushed when you have installed the Savvii Warpdrive plugin. For other actions, such as modifications to your CSS, you have to flush the cache yourself using the Cache flush button which places the Warpdrive plugin in the WP-admin.
With the actions below your cache is automatically flushed:
- Publish or remove a post or page
- Deleting or modifying an attachment
- Changing a theme
- Status change of a comment (approved, unapproved, thrash, spam)
You have to flush the cache yourself if you have done any of the things below:
- Inserting or removing plugins
- Insert or remove widgets
- Adjusting permalink settings
- Upload custom CSS, JS, images or other assets
Why isn't my dynamic content updated?
The Varnish caching makes a snapshot of your site. That's why the cached version of your site is frozen in time. For example, if you have a Twitter widget, a new tweet will not automatically end up in the cached version of your site. To do this, you have to flush the cache yourself using the Cache flush button that places the Warpdrive plugin in the WP-admin.
If your dynamic content is very important to you, it's best to contact the support desk. We'll think along with you, and maybe we'll make sure your site or part of it won't be cached anymore.