Feature Overview

The query strings override function allows you to rewrite the query strings (the parameters appened to the question mark) in the origin request URL, including add new, delete, modify, keep or ignore query strings.

Applicable Scenarios

When the query strings in the original request URL initiated by end user are different from the ones need to be passed to origin servers, you can override the query strings in the origin request URL with this function.

Procedure

Log in to CDN Console.
Go to Domain Management -> Domain List.
Find the target domain name on the Domain Lst page ,and then click Edit under Actions column.
Click Back to origin.
Go to Configuring Back-to-origin Parameter Rewrite tab.
Click Add to create overriding rules.

Options	Value	Descriptions
Rewrite mode	Append/Overwrite	Append: to add, delete,modify query strings. Overrwrite: Override the original query strings
Priority	preset value 10	The lower the number, the higher the priority.
Parameter (query string) name and value	-	Please input parameter name and value: 1.When appending parameter as a and value as 123, if parameter a is not presented in original request URL, query string a=123 will be appended to the origin request URL; if parameter a is one of the query strings in the original request URL, the value of parameter a will be modified to 123 regardless of it original value. 2.When appending parameter a with empty value means parameter a will be deleted in the origin request URL. 3. When overwriting parameter a, the value can be a solid value OR the value can be one argument of query string or other arguments： 1) If overwriting parameter a and set value as 123, then all the other query strings will be removed and only a=123 will be passed to origin. 2) If overwriting parameter a and set value as $arg_a, then all the other query strings will be removed and only query string a will be passed to origin, the value will be the one carried in the original request URL initiated end user.

Click Save and Submit.

Examples

Case 1: ignore all query strings

If the request URL sent by user is http://www.esurfingcloud.com/a/a.html?b=2&c=3&d=4, then the origin request URL will be http://www.esurfingcloud.com/a/a.html.

Case 2: Add new query strings to origin request URL

Add new query string a=123, if the request URL sent by user is http://www.esurfingcloud.com/a/a.html?b=2&c=3&d=4, then the origin request URL will be http://www.esurfingcloud.com/a/a.html?b=2&c=3&d=4&a=123 .

Case 3: Delete query strings from origin request URL

Remove query string b from origin request URL, if the request URL sent by user is http://www.esurfingcloud.com/a/a.html?b=2&c=3&d=4, then the origin request URL will be http://www.esurfingcloud.com/a/a.html?c=3&d=4 .

Case 4: keep specific query string in origin request URL

Only keep query string c in the origin request URL, if the request URL sent by user is http://www.esurfingcloud.com/a/a.html?b=2&c=3&d=4, then the origin request URL will be http://www.esurfingcloud.com/a/a.html?c=3 .

Case 5: Override value of existing query strings

Overriding the value of query string d, if the request URL sent by user is http://www.esurfingcloud.com/a/a.html?b=2&c=3&d=4, then the origin request URL will be http://www.esurfingcloud.com/a/a.html?b=2&c=3&d=123 .

Additional Considerations

If both query string parameters overriding and the ignore query string parameters are configured simultaneously, the priority of ignoring query string parameter is higher, and all the overriding parameter rules will become invalid. That is, the final effect is to ignore all query string parameters when CDN forward requests to origin.
If multiple Append and Overwrites rules are configured simultaneously, they will be executed in order by priority in which lower number has higher priority. For rules with identical priority, the rules created earlier will be executed first:

Different priorities: For example, if adding parameter a=1 is configured with a priority of 10, and at the same time, deleting parameter a is configured with a priority of 11, then the rule of adding parameter a will be executed first, and then the deteting parameter a will be executed and it's ending up with no parameter a in the origin request URL.
Same priority: For example, if you create a rule that adding parameter a=1, and then you create another rule that deleting parameter a, as a result, parameter a will not be added. And if you create the rules in contrast order, then parameter a will be added.

The query string overriding configurations are propagated to CDN edge nodes, and the overrding rules work for both the requests to CDN mid-nodes and the requests to origin.
The query string overrding does not affect the cache key settings as they are separate configurations.

Content Delivery Network

Query string overriding