title: How to combine separate timeseries labels in Prometheus query?
body: <p>I have the following timeseries entries.</p>
  
  <pre><code>ifDescr{ifDescr="GigabitEthernet1/1",ifIndex="1",instance="x.x.x.x",job="snmp"} 1
  ifDescr{ifDescr="GigabitEthernet1/2",ifIndex="2",instance="x.x.x.x",job="snmp"} 1
  ifDescr{ifDescr="GigabitEthernet5/3",ifIndex="3",instance="x.x.x.x",job="snmp"}
  ifHCInOctets{ifIndex="1",instance="x.x.x.x",job="snmp"}
  ifHCInOctets{ifIndex="2",instance="x.x.x.x",job="snmp"}
  ifHCInOctets{ifIndex="2",instance="x.x.x.x",job="snmp"}
  </code></pre>
  
  <p>As is, I have no way of telling which index matches which description, which makes things confusing.</p>
  
  <p>Is there a way to basically to do a join of the above labels using <code>ifIndex</code> to correlate to the the ifDesc label?  Or maybe the job can be used to tie the two timeseries together?</p>
  
  <p>I have looked at the <code>group_left</code> feature but haven't been able to figure out how to get it working to combine/aggregate labels.</p>