Ruby-on-rails – Does PostgreSQL support precision and scale for Rails

I have an Rails application that defines a migration that contains a decimal with precision 8 and scale 2. The database I have set up is PostgreSQL 9.1 database.

class CreateMyModels < ActiveRecord::Migration
    def change
        create_table :my_models do |t|
            t.decimal :multiplier, precison: 8, scale: 2
            t.timestamps
        end
    end
end

When I run rake db:migrate, the migration happens successfully, but I noticed an error when I was trying to run a MyModel.find_or_create_by_multiplier. If I ran the following command twice, the object would get created twice:

MyModel.find_or_create_by_multiplier(multiplier: 0.07)

I am assuming this should create the object during the first call and then find the object during the second call. Unfortunately, this does not seem to be happening with the multiplier set to 0.07.

This DOES work as expected for every other number I have thrown at the above command. The following commands work as expected (creating the object during the first call and then finding the object during the second call).

MyModel.find_or_create_by_multiplier(multiplier: 1.0)

MyModel.find_or_create_by_multiplier(multiplier: 0.05)

MyModel.find_or_create_by_multiplier(multiplier: 0.071)

When I view the PostgreSQL database description of the MyModel table, I notice that the table does not have a restriction on the numeric column.

   Column    |            Type             |                         Modifiers
-------------+-----------------------------+-------------------------------------------------------
 id          | integer                     | not null default nextval('my_models_id_seq'::regclass)
 multiplier  | numeric                     | 
 created_at  | timestamp without time zone | not null
 updated_at  | timestamp without time zone | not null

My db/schema.rb file also does not state the precision and scale:

ActiveRecord::Schema.define(:version => 20121206202800) do

...
    create_table "my_models", :force => true do |t|
        t.decimal  "multiplier"
        t.datetime "created_at",                   :null => false
        t.datetime "updated_at",                   :null => false
    end
...

So my first question is, why do I not see precision and scale pushed down to PostgreSQL when I migrate? Documentation states that it should be supported.

My second question is, why is 0.07 not correctly comparing using the MyModel.find_or_create_by_multiplier(multiplier: 0.07) command? (If I need to open another question for this, I will).