title: Find out largest string value size for keys in Redis database
body: <p>I need to look at our Redis cache and see what the size of our largest stored value is. I am experienced with Python or can use the <code>redis-cli</code> directly. Is there a way to iterate all the keys in the database  so I can then inspect the size of each value?   </p>
  
  <p>It looks like SCAN is the way to iterate through the keys, but I'm still working out how to put this to use to get the sizes of the values and store a maximum as I go.</p>