Hack: PostgreSQL unlogged tables with Rails v5.2

config-environments-test.rb

Rails.application.configure do
  # …
  
  # SEE: https://prathamesh.tech/2020/08/10/creating-unlogged-tables-in-rails/
  # SEE: config/initializers/active_record_postgresql_create_unlogged_tables_patch.rb
  config.to_prepare do
    ActiveSupport.on_load(:active_record) do
      ActiveRecord::ConnectionAdapters::PostgreSQLAdapter.create_unlogged_tables = true
    end
  end
end

config-initializers-active_record_postgresql_create_unlogged_tables_patch.rb

ActiveSupport.on_load(:active_record) do
  break if Rails.env.production?

  ActiveRecord::ConnectionAdapters::PostgreSQLAdapter.class_eval do
    # SOURCE: https://github.com/rails/rails/blob/6-0-stable/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
    class_attribute :create_unlogged_tables, default: false
  end

  ActiveRecord::ConnectionAdapters::PostgreSQL::TableDefinition.class_eval do
    attr_reader :unlogged

    # SOURCE: https://github.com/rails/rails/blob/6-0-stable/activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb
    def initialize(*, **)
      super
      @unlogged = ActiveRecord::ConnectionAdapters::PostgreSQLAdapter.create_unlogged_tables
    end
  end

  ActiveRecord::ConnectionAdapters::PostgreSQL::SchemaCreation.class_eval do
    private

    # SOURCE: https://github.com/rails/rails/blob/5-2-stable/activerecord/lib/active_record/connection_adapters/abstract/schema_creation.rb
    def visit_TableDefinition(o)
      create_sql = "CREATE#{table_modifier_in_create(o)} TABLE #{quote_table_name(o.name)} ".dup

      statements = o.columns.map { |c| accept c }
      statements << accept(o.primary_keys) if o.primary_keys

      if supports_indexes_in_create?
        statements.concat(o.indexes.map { |column_name, options| index_in_create(o.name, column_name, options) })
      end

      if supports_foreign_keys_in_create?
        statements.concat(o.foreign_keys.map { |to_table, options| foreign_key_in_create(o.name, to_table, options) })
      end

      create_sql << "(#{statements.join(', ')})" if statements.present?
      add_table_options!(create_sql, table_options(o))
      create_sql << " AS #{to_sql(o.as)}" if o.as
      create_sql
    end

    # SOURCE: https://github.com/rails/rails/blob/6-0-stable/activerecord/lib/active_record/connection_adapters/postgresql/schema_creation.rb
    def table_modifier_in_create(o)
      if o.temporary
        " TEMPORARY"
      elsif o.unlogged
        " UNLOGGED"
      end
    end
  end
end