A confusing piece of code in OutputCacheProvider

[thienvc]

Dnn.Platform/DNN Platform/HttpModules/OutputCaching/OutputCacheModule.cs

Lines 168 to 180 in 3e727b0

	foreach (string key in this.app.Context.Request.QueryString)
	{
	if (key != null && this.app.Context.Request.QueryString[key] != null)
	{
	var varyKey = key.ToLowerInvariant();
	varyBy.Add(varyKey, this.app.Context.Request.QueryString[key]);
	if (includeExclude == IncludeExcludeType.IncludeByDefault && !includeVaryByKeys.Contains(varyKey))
	{
	includeVaryByKeys.Add(varyKey);
	}
	}
	}

What does the includeVaryByKeys variable do anyway?
In the end, I found it useless
This could very well lead to a Cache Overflow error
Can someone who knows this place explain it to me?

[zyhfish]

this is used to avoid invalid cache content, if the page content is decided by some query string, for example, articleid, this can make sure the cache content will be based on article id and won't display error content to different article id values.

[thienvc]

I know, but try looking at the code to see where that variable is used?

[zyhfish]

Dnn.Platform/DNN Platform/HttpModules/OutputCaching/OutputCacheModule.cs

Line 202 in 3e727b0

string cacheKey = OutputCachingProvider.Instance(tabOutputCacheProvider).GenerateCacheKey(tabId, includeVaryByKeys, excludeVaryByKeys, varyBy);

[thienvc]

Dnn.Platform/DNN Platform/HttpModules/OutputCaching/OutputCacheModule.cs

Line 202 in 3e727b0

string cacheKey = OutputCachingProvider.Instance(tabOutputCacheProvider).GenerateCacheKey(tabId, includeVaryByKeys, excludeVaryByKeys, varyBy);

Omg, im sorry