anchor.diff:  nodes which hold the data.  Each data node executes the request locally and
   returns its results to the coordinating node. In the _gather_  phase, the
   coordinating node reduces each data node's results into a single global
  -resultset.
  +result set.
   
   Every node is implicitly a coordinating node. This means that a node that has
   an explicit empty list of roles via `node.roles` will only act as a coordinating
  
positive.code: [[transform-node]]
  ==== [xpack]#{transform-cap} node#
  
  {transform-cap} nodes run {transforms} and handle {transform} API requests. By
  default, data nodes are also transform nodes. If you have the {oss-dist}, do not
  use these settings. For more information, see <<transform-settings>>.
  
  To create a dedicated {transform} node in the {default-dist}, set:
  
  
negative.code: unexpected data then it will refuse to start. This is to avoid importing
  unwanted <<modules-gateway-dangling-indices,dangling indices>> which can lead
  to a red cluster health. To be more precise, nodes without the `data` role will
  refuse to start if they find any shard data on disk at startup, and nodes 
  without both the `master` and `data` roles will refuse to start if they have any 
  index metadata on disk at startup.
  
  It is possible to change the roles of a node by adjusting its
  `elasticsearch.yml` file and restarting it. This is known as _repurposing_ a
  