title: Redis cache for news articles
body: <p>I have a bunch of news articles (~100k at the moment). Every article can be connected with more than one category. So I have two keys <code>article URL</code> and <code>category</code>. I need to store this articles in Redis and need to group them by category. I need to get all articles of any category in fast and one article by it's URL. Also I need to have for all articles expiration time.</p>
  <p>I decided to use hash sets but then understand that hash set items have not expiration date.</p>
  <p>In short, I'm not sure where best to go from here. I'm still pretty new in this area. I wonder if there are some best practices for that.</p>