Bypassing html cache

Lately I’ve been taking a closer look on how page rendering works in Sitecore. Yesterday I’ve stumbled upon interesting behavior. It looks like by adding certain query parameter to address can result in skipping html cache. To test this I’ve written small rendering that displays DateTime.Now and marked it as cacheable. Below you can see how experiment went.

As you can see adding sc_pd_view param with any value to query string results in bypassing html cache. Same results can be observed for param sc_pd.