enixdark · September 5, 2022 18:22 · Mar 31, 2017
diff --git a/elasticsearch.rake b/elasticsearch.rake
@@ -0,0 +1,52 @@
+require 'elasticsearch/rails/tasks/import'
+
+namespace :elasticsearch do
+  desc 'Rebuild index with zerodown time'
+  task rebuild: :environment do
+    size = (ENV['size'].presence || 1000).to_i
+    model = ENV['model'].to_s.classify.constantize
+    delete_old_index = ENV['delete'].present?
+    es = model.__elasticsearch__
+
+    count = 0
+    total = model.count
+    origin_index_name = model.index_name
+    new_index_name = "#{origin_index_name}_#{Time.current.strftime('%Y%m%d%H%M%S')}"
+
+    model.find_in_batches(batch_size: size) do |group|
+      actions = group.map do |record|
+        count += 1
+        puts "Import #{model} to #{new_index_name} #{count}/#{total}"
+        { index: { _id: record.id, data: record.as_indexed_json } }
+      end
+
+      es.client.bulk(
+        index: new_index_name,
+        type: model.document_type,
+        body: actions
+      )
+    end
+
+    old_indices = begin
+      es.client.indices.get_alias(name: origin_index_name).keys
+    rescue Elasticsearch::Transport::Transport::Errors::NotFound
+      {}
+    end
+
+    actions = old_indices.map do |old_index_name|
+      { remove: { index: old_index_name, alias: origin_index_name } }
+    end
+
+    actions << { add: { index: new_index_name, alias: origin_index_name } }
+
+    es.client.indices.update_aliases(body: { actions: actions })
+
+    puts "Alias #{new_index_name} to #{origin_index_name}"
+
+    next unless delete_old_index
+    old_indices.each do |old_index_name|
+      puts "Delete #{old_index_name}"
+      es.client.indices.delete(index: old_index_name)
+    end
+  end
+end