Retain URL parameters

How it works

The parameter filtering feature can delete all or specified parameters from request URLs, and retain all or specified parameters in request URLs. The following figure shows how parameter filtering works.

Note The URL signing feature has a higher priority than the parameter filtering feature because signing type A authenticates parameters in HTTP requests. Therefore, Alibaba Cloud CDN authenticates URL parameters before it deletes or retains the parameters. Alibaba Cloud CDN performs parameter filtering only after the request passes the authentication. The parameter filtering feature does not affect the URL signing feature. The requested resources are cached on CDN nodes based on the hash keys that are generated by parameter filtering. For more information about URL signing, see URL signing.

Feature	Description
Parameter Filtering	After you enable Parameter Filtering, Alibaba Cloud CDN deletes the parameters that follow the question mark (?) from request URLs. This increases the cache hit ratio. For example, the first time http://www.****.com/1.jpg is visited, the requested resource is not cached on CDN nodes. Therefore, Alibaba Cloud CDN must retrieve the requested resource from the origin server. When http://www.****.com/1.jpg?test1 is visited, the URL parameters that follow the question mark (?) are deleted because parameter filtering is enabled. The request can directly hit the cached resource of http://www.****.com/1.jpg.
Parameter Filtering+Retain Specified Parameters	After you enable Parameter Filtering and specify the parameters that you want to retain, the specified parameters that follow the question mark (?) in request URLs are retained. Other parameters are deleted.
Retain Origin Parameters	If you enable Retain Origin Parameters, Alibaba Cloud CDN retains all parameters that follow the question mark (?) in request URLs during the back-to-origin process. If you do not enable Retain Origin Parameters, only the specified URL parameters are retained during the back-to-origin process.

Procedure

1. Log on to the Alibaba Cloud CDN console.
2. In the left-side navigation pane, click Domain Names.
3. On the Domain Names page, find the domain name that you want to manage and click Manage in the Actions column of the domain name.
4. In the management pane of the domain name, click Optimization.
5. In the Parameter Filtering (Retain Specified Parameters) section, click Modify.
6. Set the following parameters based on the instructions.
   

   Parameter	Description
   Parameter Filtering	Turn on Parameter Filtering.
   Retain Specified Parameters	Specify the parameters that you want to retain based on your business requirements. You can specify up to 10 parameters to be retained. Separate multiple parameters with commas (,). For example, for the URL http://www.abc.com/a.jpg?x, set Retain Specified Parameters to x. Note If you set only the Retain Specified Parameters parameter, parameters are not retained. You must also turn on Parameter Filtering. You can also turn on Retain Origin Parameters based on business requirements.
   Retain Origin Parameters	Turn on or turn off Retain Origin Parameters based on your business requirements. If you enable Retain Origin Parameters, Alibaba Cloud CDN retains all parameters that follow the question mark (?) in request URLs during the back-to-origin process. If you do not enable Retain Origin Parameters, only the specified URL parameters are retained during the back-to-origin process.

7. Click OK.

Related API operations

BatchSetCdnDomainConfig