title: How to calculate the hourly Max over a month, promql
body: <p>I have the following query, intended to calculate for each hour the max value, over a month.
  The final result should be- for each parentnode, the hourly max over the last month</p>
  <p>I have this for now:</p>
  <pre><code>max_over_time((node_memory_MemTotal_bytes{site=&quot;fra&quot;,parentnode=&quot;compute_node&quot;} - node_memory_MemFree_bytes{site=&quot;fra&quot;,parentnode=&quot;compute_node&quot;} - node_memory_Cached_bytes{site=&quot;fra&quot;,parentnode=&quot;compute_node&quot;} - node_memory_Buffers_bytes{site=&quot;fra&quot;,parentnode=&quot;compute_node&quot;} - node_memory_Slab_bytes{site=&quot;fra&quot;,parentnode=&quot;compute_node&quot;})[1h])
  </code></pre>
  <p>Thank you.</p>