Remove notes index on updated_at

changelogs/unreleased/53988-remove-notes-index-on-updated-at.yml

+---
+title: Remove index for notes on updated_at
+merge_request: 23356
+author:
+type: performance

db/migrate/20181126153547_remove_notes_index_on_updated_at.rb

+# frozen_string_literal: true
+
+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class RemoveNotesIndexOnUpdatedAt < ActiveRecord::Migration[5.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    remove_concurrent_index(*index_arguments)
+  end
+
+  def down
+    add_concurrent_index(*index_arguments)
+  end
+
+  private
+
+  def index_arguments
+    [
+      :notes,
+      [:updated_at],
+      {
+        name: 'index_notes_on_updated_at'
+      }
+    ]
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20181126150622) do
+ActiveRecord::Schema.define(version: 20181126153547) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -1392,7 +1392,6 @@ ActiveRecord::Schema.define(version: 20181126150622) do
     t.index ["noteable_id", "noteable_type"], name: "index_notes_on_noteable_id_and_noteable_type", using: :btree
     t.index ["noteable_type"], name: "index_notes_on_noteable_type", using: :btree
     t.index ["project_id", "noteable_type"], name: "index_notes_on_project_id_and_noteable_type", using: :btree
-    t.index ["updated_at"], name: "index_notes_on_updated_at", using: :btree
   end
 
   create_table "notification_settings", force: :cascade do |t|