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Caching

Cookies

The VIP Platform caching system does not vary for most cookies (exceptions listed below). If a site’s content is personalized based on a cookie that is not in this list, the response will be cached and served to the next user regardless of whether they have that cookie with the same value or not.

If a request has one of the following cookies, it will PASS cache (the request and response will be considered uncacheable):

  • A WordPress comment cookie
  • A WordPress test cookie
  • A WordPress post password cookie
  • A WordPress authentication cookie
  • A WooCommerce session cookie
  • The VIP cache bypass cookie vip-go-cb (must have a value of exactly 1)
  • A PHP session cookie

If the TTL is less than or equal to 0 AND the response status code is less than 400, OR there’s a Set-Cookie header, OR a Cache-Control header with a private value, OR a Vary header with a value of *, then that URL will be marked as uncacheable (hit-for-pass) for 10 seconds.

Cookies may have a negative performance impact

Setting cookies on busy pages or endpoints, especially if those routes are not exceptionally fast, can affect the stability of your application. Many requests will go to origin servers for the same content.

In most cases, the most straightforward way to handle the limitations above is to move user-level interactions client-side using JavaScript, and if needed, fast AJAX requests.

Some additional tips for server generated pages or URLs that are often uncacheable because of cookie use:

  • optimize the performance of these pages
  • utilize Query Monitor and other tools, such as New Relic, to identify and analyze bottlenecks
  • utilize, as much as possible, object cache to save data that may take significant time to query or generate, or that must be fetched remotely
  • avoid cache expirations on frequently used items, these can cause a cache stampede
  • similarly, suddenly setting cookies for a lot of site visitors can cause increased origin requests that may ramp up too fast to be absorbed by autoscaling… consider staggering the inception or introduction of campaigns and cookie changes

Last updated: January 18, 2022