Hello Alexander,
Specifically, the purge_pattern parameter allows you to purge specific resources without purging a site's entire cache. For example, if you had a large number of GIF images that you had modified and wanted to only purge the cached GIFs, you could use an API call along the following lines:
https://my.incapsula.com/api/prov/v1/sites/cache/purge?api_id=X&api_key=Y&site_id=Z&purge_pattern=.gif$
This would purge anything that ends with ".gif". Alternatively, if you had a large number of files that began with "example_file", you could do the following:
https://my.incapsula.com/api/prov/v1/sites/cache/purge?api_id=X&api_key=Y&site_id=Z&purge_pattern=^example_file
This would purge anything that began with "example file".
Note that this parameter is also optional - if all you wish to do is simply purge the entire site cache, you can do so by omitting the "purge_pattern" parameter.
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Clinton Nicholls III
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