Add events index on project_id and created_at

changelogs/unreleased/53992-add-events-index-on-project-id-and-created-at.yml

+---
+title: Add index for events on project_id and created_at
+merge_request: 23354
+author:
+type: performance

db/migrate/20181126150622_add_events_index_on_project_id_and_created_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 AddEventsIndexOnProjectIdAndCreatedAt < ActiveRecord::Migration[5.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    add_concurrent_index(*index_arguments)
+  end
+
+  def down
+    remove_concurrent_index(*index_arguments)
+  end
+
+  private
+
+  def index_arguments
+    [
+      :events,
+      [:project_id, :created_at],
+      {
+        name: 'index_events_on_project_id_and_created_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: 20181112103239) do
+ActiveRecord::Schema.define(version: 20181126150622) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -867,6 +867,7 @@ ActiveRecord::Schema.define(version: 20181112103239) do
     t.string "target_type"
     t.index ["action"], name: "index_events_on_action", using: :btree
     t.index ["author_id", "project_id"], name: "index_events_on_author_id_and_project_id", using: :btree
+    t.index ["project_id", "created_at"], name: "index_events_on_project_id_and_created_at", using: :btree
     t.index ["project_id", "id"], name: "index_events_on_project_id_and_id", using: :btree
     t.index ["target_type", "target_id"], name: "index_events_on_target_type_and_target_id", using: :btree
   end