anchor.diff:  [[docs-reindex]]
   === Reindex API
  -
  -IMPORTANT: Reindex requires <<mapping-source-field,`_source`>> to be enabled for
  +++++
  +<titleabbrev>Reindex</titleabbrev>
  +++++
  +
  +Copies documents from one index to another. 
  +
  +[IMPORTANT]
  +=================================================
  +Reindex requires <<mapping-source-field,`_source`>> to be enabled for
   all documents in the source index.
   
  -IMPORTANT: Reindex does not attempt to set up the destination index.  It does
  -not copy the settings of the source index.  You should set up the destination
  -index prior to running a `_reindex` action, including setting up mappings, shard
  -counts, replicas, etc.
  -
  -The most basic form of `_reindex` just copies documents from one index to another.
  -This will copy documents from the `twitter` index into the `new_twitter` index:
  +You must set up the destination index before calling `_reindex`.
  +Reindex does not copy the settings from the source index. 
  +Mappings, shard counts, replicas, and so on must be configured ahead of time.
  +=================================================
   
   [source,console]
   --------------------------------------------------
  
positive.code: * Each sub-request gets a slightly different snapshot of the source index,
  though these are all taken at approximately the same time.
  
  [float]
  [[docs-reindex-picking-slices]]
  ====== Picking the number of slices
  
  
negative.code: The previous method can also be used in conjunction with <<docs-reindex-change-name, changing a field name>>
  to load only the existing data into the new index and rename any fields if needed.
  
  [[docs-reindex-api-subset]]
  ===== Extract a random subset of an index
  
  `_reindex` can be used to extract a random subset of an index for testing:
  
  