Cookies that bypass cache

The behavior of the page cache does not vary for most cookies. For sites that personalize content based on a cookie that is not listed below, the response will be cached and served to the next user regardless of whether they have that cookie with the same value or not.

A URL will be marked as BYPASS cache (the request and response will be considered uncacheable) if the request has one of the following cookies:

• A WordPress comment cookie
• A WordPress test cookie
• A WordPress post password cookie
• A WordPress authentication cookie
• A WooCommerce session cookie
• A PHP session cookie
• The VIP cache bypass cookie vip-go-cb set to the exact value of 1

The vip-go-cb cache bypass cookie 

vip-go-cb is a VIP Platform cookie that can be used by WordPress or Node.js applications. The cookie allows incoming requests with a value set to 1 to bypass the page cache. This method prevents personalized responses from being cached and served to other users.

• Requests with the vip-go-cb cookie set to a value of 1 (it must be a value of 1) will always BYPASS the page cache. As a result, these requests will never be served a cached response, and the response to these requests will never be cached to be served to others.
• On WordPress applications, requests from logged-in users will always BYPASS the cache; setting this cookie for logged-in WordPress users is not necessary. If users are logging in using a different mechanism, set the vip-go-cb cookie in addition to any other cookies or local storage data for a third-party login system. Be sure that these users will not have responses cached or see cached responses.

Avoid negative performance impact

Setting cookies on pages or endpoints can negatively affect the stability of a site, particularly if those pages or endpoints are not performant. Requests to URLs that set a cookie or bypass the cache will result in SQL queries on the origin server. This can have negative performance implications for a site, particularly during a high traffic event. A large volume of direct SQL queries can overload the primary database and lead to an increase in responses with a 503 HTTP status code.

To improve the performance of server-generated pages or URLs that bypass the cache due to cookie usage:

• Optimize WordPress database queries to improve the performance of these pages when they bypass the cache.
• Use the object cache as much as possible to save data that may take significant time to query or generate, or that must be fetched remotely.
• Move user-level interactions to client-side using JavaScript and fast AJAX requests whenever possible.
• Avoid events that cause the cache to frequently expire, as doing so can cause a cache stampede.
• Refer to Query Monitor, New Relic, and other tools to identify and analyze bottlenecks.
• Stagger the release of campaigns and cookie-related changes. Suddenly setting cookies for a large number of site visitors can cause an increase in requests to origin that may occur too quickly to be absorbed by autoscaling.