Best way to add_index to database

I think one extra migration fits well:

class AddIndexes < ActiveRecord::Migration  def self.up    add_index :prices, :user_id    add_index :prices, :price  end  def self.down    remove_index :prices, :user_id    remove_index :prices, :price  endend

Or you can use change syntax with newer versions of rails, look at DonamiteIsTnt comment for details:

class AddIndexes < ActiveRecord::Migration  def change    add_index :prices, :user_id    add_index :prices, :price  endend

Once an app is in production, the intent is that migrations will be applied once.

If you're still developing your app, you can always add them as you've noted followed by a rake db:migrate:reset this will wipe your database and re-create it.

Otherwise, create a new migration rails g migration add_user_id_index.

class AddUserIdIndex < ActiveRecord::Migration  def self.up    add_index :prices, :user_id  end  def self.down    remove_index :prices, :user_id  endend

FWIW, add_index :prices doesn't make sense. Indexes are per-column, not per-table.

You can always manually create indexes by logging into your database.

CREATE INDEX prices__user_id__idx ON prices (user_id);

Simple solution:

• create a new migration
• add the indexes there (they don't need to be in the older migrations)
• run the migrations