code: func (r Req) Trace(span opentracing.Span) {
  	span.SetTag("key", r.MKey)
  	span.SetTag("target", r.Target)
  	span.SetTag("pattern", r.Pattern)
  	span.SetTag("from", r.From)
  	span.SetTag("to", r.To)
  	span.SetTag("span", r.To-r.From-1)
  	span.SetTag("mdp", r.MaxPoints)
  	span.SetTag("rawInterval", r.RawInterval)
  	span.SetTag("cons", r.Consolidator)
  	span.SetTag("consReq", r.ConsReq)
  	span.SetTag("schemaId", r.SchemaId)
  	span.SetTag("aggId", r.AggId)
  	span.SetTag("archive", r.Archive)
  	span.SetTag("archInterval", r.ArchInterval)
  	span.SetTag("TTL", r.TTL)
  	span.SetTag("outInterval", r.OutInterval)
  	span.SetTag("aggNum", r.AggNum)
  }
docs: // Trace puts all request properties as tags in a span
  // good for when a span deals with 1 request