title: How to create a downsampling on downsampled key in redis timeseries
body: <p>Here is the use case:</p>
  <p>I have metric called <code>count</code>
  I am downsampling it by creating a rule to the key/downsampling rule <code>countPerMinute</code></p>
  <p>Now when I try and create another rule for hourlyAggregation(have a slightly complicated case) redis time series doesn't allow me to create a rule with the <code>countPerMinute</code> key as a source key for another rule.</p>
  <p>As there are millions of keys and huge volume we have set only couple hours of retention period on raw data keys.</p>