How to make place2.rb into only 1 query?

event.rb

class Event < ActiveRecord::Base
  belongs_to :owner, class_name: 'User', foreign_key: 'user_id'
  belongs_to :place
  has_many :photos, as: :parent

  validates_presence_of :name, :owner
end

photo.rb

class Photo < ActiveRecord::Base
  belongs_to :parent, polymorphic: true
  belongs_to :owner, class_name: 'User', foreign_key: 'user_id'

  validates_presence_of :owner, :file

  mount_uploader :file, PhotoUploader
end

place.rb

class Place < ActiveRecord::Base
  belongs_to :owner, class_name: 'User', foreign_key: 'user_id'
  has_many :photos, as: :parent

  validates_presence_of :name, :city, :country, :owner
  validates_uniqueness_of :name
end

place2.rb

def all_photos
  Photo.joins("INNER JOIN events ON events.id = parent_id")
    .joins("INNER JOIN places ON places.id = events.place_id")
    .where("places.id = #{id}")
    .concat self.photos
end

Place.first.all_photos.size
-> SELECT "photos".* FROM "photos" INNER JOIN events ON events.id = parent_id INNER JOIN places ON places.id = events.place_id WHERE (places.id = 6)
-> SELECT "photos".* FROM "photos" WHERE "photos"."parent_id" = $1 AND "photos"."parent_type" = $2  [["parent_id", 6], ["parent_type", "Place"]]

user.rb

class User < ActiveRecord::Base
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable, :token_authenticatable

  has_many :events
  has_many :photos
  has_many :places
end