Decimal column with zero scale dumped as integer column

If you declare a decimal column with a scale of 0 in a migration:

create_table :large_integers do |t|
  t.decimal :large, :scale => 0, :precision => 80

  t.timestamps
end

Then a table will be created like the following:

large      | numeric(40,0)               |
created_at | timestamp without time zone | 
updated_at | timestamp without time zone |

But, after running rake db:schema:dump, db/schema.rb will contain something like the following:

create_table "large_integers", :force => true do |t|
  t.integer  "large",      :limit => 80, :precision => 80, :scale => 0
  t.datetime "created_at"
  t.datetime "updated_at"
end

On PostgreSQL, this will create an integer column, not a numeric column, and if the precision is large then the column can not hold numbers up to that precision.

Plus, it is a little surprising to have schema.rb differing from your migration like this.

The attached patch fixes this problem in the schema dumper by looking for integer columns where the underlying sql_type is decimal or numeric, and then setting the type to be emitted to 'decimal' instead of 'integer'.