tracks/db/migrate/037_add_index_to_notes.rb

class AddIndexToNotes < ActiveRecord::Migration[5.2]
  def self.up
    add_index :notes, [:project_id]
    add_index :notes, [:user_id]
  end

  def self.down
    remove_index :notes, [:user_id]
    remove_index :notes, [:project_id] 
  end
end