Migration -> change_table -> bulk not working?

Question

PostgreSQL

Hello. Windows 10 x64, Rails 5.1.3, Ruby 2.4.1p111 (2017-03-22 revision 58053) [x64-mingw32], PostgreSQL .6
Don't tell me why the :bulk option in change_table does not work in migrations

class Test2 < ActiveRecord::Migration[5.1]
  def change
    change_table :testes, { bulk: true } do |t|
      t.string :test1, :test2, :test3, limit: 3
      t.string :test4, limit: 3
    end
  end
end

Here is the log:

(1.0ms)  BEGIN
   (0.5ms)  ALTER TABLE "testes" ADD "test1" character varying(3)
   (0.5ms)  ALTER TABLE "testes" ADD "test2" character varying(3)
   (0.5ms)  ALTER TABLE "testes" ADD "test3" character varying(3)
   (0.5ms)  ALTER TABLE "testes" ADD "test4" character varying(3)
  SQL (0.5ms)  INSERT INTO "schema_migrations" ("version") VALUES ($1) RETURNING "version"  
   (0.5ms)  COMMIT

but in theory, as I understand it, the creation should be one team

alter table testes add column test1 varchar(3), add column test2 varchar(3), add column test3 varchar(3), add column test4 varchar(3)

Thank you.

Answer 1

postgresql base?
If you look at the rails code for change_table , you can see that rails checks the supports_bulk_alter? condition defined in abstrtact_adapter and returns false. There is an override for mysql , while pg does not override this method