title: Elastic search map multiple fields to a single field
body: <p>Does elastic search provide a functionality to map different fields to a single field and use that single field for search.</p>
  
  <p>For eg _all refers to all the fields in the docs. </p>
  
  <p>Similarly do we have any mapping configuration to define a field which would be referring to multiple fields.</p>
  
  <p>Eg : I have a field called Brand,Name,Category.</p>
  
  <p>I need to map Brand and Name to a single field custome_field.</p>
  
  <p>I want it during mapping time and not during query time. I know cross fields does that during query time.</p>