If you enable ignore parameters, Alibaba Cloud CDN edge nodes remove the parameters (query strings) that follow the question mark (?) in request URLs. These parameters contain information such as user identities and request sources. However, the original URLs are used as the cache keys. This topic describes how to configure the parameter filtering feature.

Overview

  • parameter filtering
    Description Scenario
    Alibaba Cloud CDN removes the parameters that follow the question mark (?) in request URLs so that requests that are destined for the same file but carry different URL parameters can hit the cache. Parameter filtering increases the cache hit ratio, reduces the back-to-origin routing frequency, and accelerates file distribution. Some users append parameters after the question mark (?) in request URLs to pass information such as user IDs (UIDs), request sources, and recommendation codes to the origin servers. In this case, these URLs carry different query strings even if the requests are sent to the same file.
    We recommend that you enable parameter filtering if the parameters that follow the question mark (?) in URLs are irrelevant to the requested resource. Examples:
    • Request from User A: http://example.com/1.jpg?uid=123***
    • Request from User B: http://example.com/1.jpg?uid=654***
    If the CDN edge node uses the original URLs from User A and User B, the requests cannot hit the same file in the cache. The requests must be redirected to the origin server.

    After parameter filtering is enabled, the CDN edge node removes the UIDs that follow the question mark (?) in the request URLs. The final URL http://example.com/1.jpg is used to match against the cache.

  • Retain parameters in back-to-origin requests
    Description Scenario
    The original URLs are redirected to the origin servers so that key user information can be passed to the origin servers. If you enable parameter filtering, CDN edge nodes redirect the URLs processed by parameter filtering to the origin servers. In the preceding example, the requests from User A and User B both use the URL http://example.com/1.jpg. The UIDs are not passed to the origin server during back-to-origin routing.

    If parameter filtering is enabled, CDN edge nodes redirect the original URLs to the origin server so that the UIDs are passed to the origin server.

Parameter filtering can retain or remove specified parameters. The following figure shows how to enable parameter filtering.Parameter filtering

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.
  4. In the left-side management pane of the domain name, click Optimization.
  5. In the Ignore Parameters section, click Modify, select a filtering mode based on your business requirements, and then set the parameters.
    Notice If you change the filtering mode, the exiting settings are cleared.
    • Filter mode: retain specified URL parametersParameter filtering
      Parameter Description Example
      Parameter Filtering
      • Yes: enables parameter filtering. Parameters that follow the question mark (?) are removed from the URLs.
        Note If you enable Parameter Filtering and do not set the Retain Specified Parameters parameter, all parameters that follow the question mark (?) are removed.
      • No: disables parameter filtering.
      If the original URL is http://example.com/1.jpg?key1=1&key2=2&key3=3, the follow examples show how the URL is processed based on different settings:
      • Example 1: remove all parameters and redirect the final URL to the origin server.
        • Parameter settings: Parameter Filtering is set to Yes, no value is specified for Retain Specified Parameters, and Retain Origin Parameters is set to No.
        • Cache key: http://example.com/1.jpg.
        • URL redirected to the origin server: http://example.com/1.jpg.
      • Example 2: retain specified parameters and redirect the final URL to the origin server.
        • Parameter settings: Parameter Filtering is set to Yes, Retain Specified Parameters is set to key1, and Retain Origin Parameters is set to No.
        • Cache key: http://example.com/1.jpg?key1=1.
        • URL redirected to the origin server: http://example.com/1.jpg?key1=1.
      • Example 3: remove all parameters and redirect the original URL to the origin server.
        • Parameter settings: Parameter Filtering is set to Yes, no value is specified for Retain Specified Parameters, and Retain Origin Parameters is set to Yes.
        • Cache key: http://example.com/1.jpg.
        • URL redirected to the origin server: http://example.com/1.jpg?key1=1&key2=2&key3=3.
      • Example 4: retain specified parameters and redirect the original URL to the origin server.
        • Parameter settings: Parameter Filtering is set to Yes, Retain Specified Parameters is set to key1, and Retain Origin Parameters is set to Yes.
        • Cache key: http://example.com/1.jpg?key1=1
        • URL redirected to the origin server: http://example.com/1.jpg?key1=1&key2=2&key3=3.
      Retain Specified URL Parameters You can retain at most 10 parameters. Separate parameters with commas (,).
      Retain Parameters in Back-to-origin Parameters
      • Yes: retains all parameters in URLs during back-to-origin routing.
      • No: retains only specified parameters in URLs during back-to-origin routing. The parameters remain the same as those in the cache key.
    • Filtering mode: remove specified parametersRemove specified parameters
      Parameter Description Example
      Delete Specified Parameters Specify the parameters that you want to remove. You can specify at most 10 parameters. Separate parameters with commas (,). If the original URL is http://example.com/1.jpg?key1=1&key2=2&key3=3, the following examples show how the URL is processed based on different settings:
      • Example 1: remove specified parameters and redirect the final URL to the origin server.
        • Parameter filtering: Delete Specified Parameters is set to key1, and Retain Origin Parameters is set to No.
        • Cache key: http://example.com/1.jpg?key2=2&key3=3.
        • URL redirected to the origin server: http://example.com/1.jpg?key2=2&key3=3.
      • Example 2: remove specified parameters and redirect the original URL to the origin server.
        • Parameter settings: Delete Specified Parameters is set to key1, and Retain Origin Parameters is set to Yes.
        • Cache key: http://example.com/1.jpg?key2=2&key3=3.
        • URL redirected to the origin server: http://example.com/1.jpg?key1=1&key2=2&key3=3.
      Retain Parameters in Back-to-origin Parameters
      • Yes: retains all parameters in URLs during back-to-origin routing.
      • No: removes only specified parameters in URLs during back-to-origin routing. The parameters remain the same as those in the cache key.
  6. Click OK.