Add index on `requested_at` to the `members` table

Signed-off-by: Rémy Coutable <remy@rymai.me>

db/migrate/20160615142710_add_index_on_requested_at_to_members.rb

+class AddIndexOnRequestedAtToMembers < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  disable_ddl_transaction!
+
+  def change
+    add_concurrent_index :members, :requested_at
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20160610301627) do
+ActiveRecord::Schema.define(version: 20160615142710) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -572,6 +572,7 @@ ActiveRecord::Schema.define(version: 20160610301627) do
   add_index "members", ["access_level"], name: "index_members_on_access_level", using: :btree
   add_index "members", ["created_at", "id"], name: "index_members_on_created_at_and_id", using: :btree
   add_index "members", ["invite_token"], name: "index_members_on_invite_token", unique: true, using: :btree
+  add_index "members", ["requested_at"], name: "index_members_on_requested_at", using: :btree
   add_index "members", ["source_id", "source_type"], name: "index_members_on_source_id_and_source_type", using: :btree
   add_index "members", ["type"], name: "index_members_on_type", using: :btree
   add_index "members", ["user_id"], name: "index_members_on_user_id", using: :btree