Truncate a single table across multiple db types. I made this a private method in my application controller (app/controllers/application_controller.rb). Adapted from: https://gist.github.com/tvdeyen/3246525

truncate_table.rb

  def truncate_table table_name
    config = Rails.configuration.database_configuration
    connection = ActiveRecord::Base.connection
    connection.disable_referential_integrity do
      next if connection.select_value("SELECT count(*) FROM #{table_name}") == 0
      case config[Rails.env]["adapter"]
      when "mysql", "mysql2", "postgresql"
        connection.execute("TRUNCATE #{table_name}")
      when "sqlite", "sqlite3"
        connection.execute("DELETE FROM #{table_name}")
        connection.execute("DELETE FROM sqlite_sequence where name='#{table_name}'")
      end
      connection.execute("VACUUM") if config[Rails.env]["adapter"] == "sqlite3"
    end
  end