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Notes on using Materialize Views in Rails

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I’ve been doing occasional work with Materialized views in Rails. Capturing some notes.

The Usual Steps #

copy/rename the view(s) I’m modifying #

increment the version number by 1: db/views/given_view_v04.sql -> db/views/given_view_v05.sql

write migration for each updated view # 

rails g migration update_given_view_to_version_5

# frozen_string_literal: true
class UpdateGivenViewToVersion5 < ActiveRecord::Migration[6.0]
  def change
    ActiveRecord::Base.connection.execute 'SET statement_timeout = 0'

    update_view :given_view, version: 5, revert_to_version: 4, materialized: true
  end
end

# app/models/given_view.rb
class GivenView < ApplicationRecord
  belongs_to :other_thing

  def self.refresh(concurrently: true)
    Scenic.database.refresh_materialized_view(table_name, concurrently: concurrently, cascade: false)
  end

  def readonly?
    true
  end
end

# spec/models/given_view_spec.rb
# frozen_string_literal: true

require 'rails_helper'

RSpec.describe GivenView, type: :model do
  context 'v6 refinements' do
      it "correctly filters out certain objects" do
        object_to_be_excluded = create(
          :object,
          :refinement_1,
          :refinement_2,
          association: associated_object
        )

        described_class.refresh(concurrently: false)

        expect(described_class.all.pluck(:id)).not_to include(object_to_be_excluded.id)
      end
end

Resources/extra reading #