Cache size management via query parameter busting.
Posted by Max Robbins on October 25th, 2010You can also keep some of the parameters in the query portion of the URL, while removing others. Such modification only affect the cached response’s signature and have no effect on anything else. Again, this is done to optimize performance and reduce waste that would occur otherwise. Let’s consider this URL:
www.acmenews.com/showstory.asp?storyid=1234&partnerid=partner1
We must use query string in addition to the URL path to be able to cache proper responses – so we can not use the cache-by-path feature, as it ignores the query string entirely. Yet once again we have a parameter added to the query string that doesn’t affect the response.
aiCache to the rescue ! We can ignore the partnerid parameter, while keeping the storyid in the signature. To accomplish that, create a pattern that matches this url (something like showstory.asp might be all you need) and specify:
ignoreparam parnerid
in the parameter section. Now
www.acmenews.com/showstory.asp?storyid=1234&partnerid=partner1
will be transformed to
www.acmenews.com/showstory.asp?storyid=1234
and that is what will be used as cached response’s signature.
You can ignore one parameter, a few or all of them, although ignoring all of them is best accomplished via cache-by-path feature.
Quite frequently web sites use a technique called “cache-busting” . It mostly boils down to adding a parameter whose value is a random string. It is aimed at making sure any HTTP caches between a visitor and the target web site do not cache content. When such cache-busting parameters are used in URLs of cacheable responses, you’re advised to configure Aicache it to remove such cache-busting parameter from URL signature. Figure out what the cache busting parameter name is and add it as ignoreparam setting under the proper URL patterns.