Purge and prefetch is the update mechanism for resources cached in CDN nodes. This document describes how to purge and prefetch resources based on
URL in VOD.
FileIdis the ID of an audio/video media file in VOD. A
FileIdis used for all operational outputs (e.g., transcoding or screencapturing) of a file. Therefore, when you purge or prefetch a
FileId, both the original video file and the output files (e.g., transcoded videos and screenshots) will take effect.
URLis the audio/video URL in VOD.
URLis specific to an audio/video media file. Therefore, when you purge or prefetch a
URL, only the corresponding file will take effect.
Once you perform a cache purge on a resource, the system will delete the existing cache of the resource from the CDN nodes across the network. When a user request arrives at a node, the node will pull the corresponding resource from the origin server, return the request, and cache the resource, ensuring that the user obtains the latest resource.
When a resource is prefetched, it will be cached in advance to all the CDN nodes across the network. When a user request arrives at a node, the resource can be directly obtained, and response time is shortened.