README.md in elasticsearch-extensions-0.0.20 vs README.md in elasticsearch-extensions-0.0.21

@@ -21,9 +21,88 @@
     rake install
 
 
 ## Extensions
 
+### Backup
+
+Backup Elasticsearch indices as flat JSON files on the disk via integration
+with the [_Backup_](http://backup.github.io/backup/v4/) gem.
+
+Use the Backup gem's DSL to configure the backup:
+
+    require 'elasticsearch/extensions/backup'
+
+    Model.new(:elasticsearch_backup, 'Elasticsearch') do
+
+      database Elasticsearch do |db|
+        db.url     = 'http://localhost:9200'
+        db.indices = 'test'
+      end
+
+      store_with Local do |local|
+        local.path = '/tmp/backups'
+      end
+
+      compress_with Gzip
+    end
+
+Perform the backup with the Backup gem's command line utility:
+
+    $ backup perform -t elasticsearch_backup
+
+See more information in the [`Backup::Database::Elasticsearch`](lib/extensions/backup.rb)
+class documentation.
+
+### Reindex
+
+Copy documents from one index and cluster into another one, for example for purposes of changing
+the settings and mappings of the index.
+
+**NOTE:** Elasticsearch natively supports re-indexing since version 2.3. This extension is useful
+          when you need the feature on older versions.
+
+When the extension is loaded together with the
+[Ruby client for Elasticsearch](../elasticsearch/README.md),
+a `reindex` method is added to the client:
+
+    require 'elasticsearch'
+    require 'elasticsearch/extensions/reindex'
+
+    client = Elasticsearch::Client.new
+    target_client = Elasticsearch::Client.new url: 'http://localhost:9250', log: true
+
+    client.index index: 'test', type: 'd', body: { title: 'foo' }
+
+    client.reindex source: { index: 'test' },
+                   target: { index: 'test', client: target_client },
+                   transform: lambda { |doc| doc['_source']['title'].upcase! },
+                   refresh: true
+    # => { errors: 0 }
+
+    target_client.search index: 'test'
+    # => ... hits ... "title"=>"FOO"
+
+The method takes similar arguments as the core API
+[`reindex`](http://www.rubydoc.info/gems/elasticsearch-api/Elasticsearch/API/Actions#reindex-instance_method)
+method.
+
+You can also use the `Reindex` class directly:
+
+    require 'elasticsearch'
+    require 'elasticsearch/extensions/reindex'
+
+    client = Elasticsearch::Client.new
+
+    reindex = Elasticsearch::Extensions::Reindex.new \
+                source: { index: 'test', client: client },
+                target: { index: 'test-copy' }
+
+    reindex.perform
+
+See more information in the [`Elasticsearch::Extensions::Reindex::Reindex`](lib/extensions/reindex.rb)
+class documentation.
+
 ### ANSI
 
 Colorize and format selected  Elasticsearch response parts in terminal:
 
 Display formatted search results: