Rails mass migration to add indexes

999_add_indexes.rb

class AddIndexes < ActiveRecord::Migration

  INDEXES = {
    :blogs => %w/title author_id/,
    :comments => %w/blog_id subject poster_id/,
    :events => %w/name place when/
  }

  def up
    INDEXES.each { |table, cols |
      cols.each { |col| add_index table, col }
    }
  end

  def down
    INDEXES.each { |table, cols |
      cols.each { |col| remove_index table, col }
    }
  end

end