anchor.diff:  // TESTRESPONSE
   
   Or you can search by `tag` or whatever you want.
  +
  +
  +[float]
  +=== Reindex daily indices
  +
  +You can use `_reindex` in combination with <<modules-scripting-painless, Painless>>
  + to reindex daily indices to apply a new template to the existing documents.
  +
  +Assuming you have indices consisting of documents as following:
  +
  +[source,js]
  +----------------------------------------------------------------
  +PUT metricbeat-2016.05.30/beat/1?refresh
  +{"system.cpu.idle.pct": 0.908}
  +PUT metricbeat-2016.05.31/beat/1?refresh
  +{"system.cpu.idle.pct": 0.105}
  +----------------------------------------------------------------
  +// CONSOLE
  +
  +The new template for the `metricbeat-*` indices is already loaded into elasticsearch
  +but it applies only to the newly created indices. Painless can be used to reindex
  +the existing documents and apply the new template.
  +
  +The script below extracts the date from the index name and creates a new index
  +with `-1` appended. All data from `metricbeat-2016.05.31` will be reindex
  +into `metricbeat-2016.05.31-1`.
  +
  +[source,js]
  +----------------------------------------------------------------
  +POST _reindex
  +{
  +  "source": {
  +    "index": "metricbeat-*"
  +  },
  +  "dest": {
  +    "index": "metricbeat"
  +  },
  +  "script": {
  +    "lang": "painless",
  +    "inline": "ctx._index = 'metricbeat-' + (ctx._index.substring('metricbeat-'.length(), ctx._index.length())) + '-1'"
  +  }
  +}
  +----------------------------------------------------------------
  +// CONSOLE
  +// TEST[continued]
  +
  +All documents from the previous metricbeat indices now can be found in the `*-1` indices.
  +
  +[source,js]
  +----------------------------------------------------------------
  +GET metricbeat-2016.05.30-1/beat/1
  +GET metricbeat-2016.05.31-1/beat/1
  +----------------------------------------------------------------
  +// CONSOLE
  +// TEST[continued]
  +
  +The previous method can also be used in combination with <<docs-reindex-change-name, change the name of a field>>
  +to only load the existing data into the new index, but also rename fields if needed.
  
positive.code: timeouts.
  
  [float]
  === Reindex to change the name of a field
  
  `_reindex` can be used to build a copy of an index with renamed fields. Say you
  
negative.code: Elasticsearch can reclaim the space it uses.
  
  `wait_for_active_shards` controls how many copies of a shard must be active
  before proceeding with the reindexing. See <<index-wait-for-active-shards,here>>
  for details. `timeout` controls how long each write request waits for unavailable
  shards to become available. Both work exactly how they work in the
  <<docs-bulk,Bulk API>>.
  