```ruby
class ThinkingSphinx::ActiveRecord::Callbacks::DeltaCallbacks <
  ThinkingSphinx::Callbacks

  callbacks :after_commit, :before_save

  def after_commit
    return unless !suspended? && delta_indices? && toggled?

    delta_indices.each do |index|
      index.delta_processor.index index
    end

    core_indices.each do |index|
      index.delta_processor.delete index, instance
    end
  end

  def before_save
    return unless new_or_changed?           &&
      !ThinkingSphinx::Callbacks.suspended? &&
      delta_indices?

    processors.each { |processor| processor.toggle instance }
  end

  private

  def config
    ThinkingSphinx::Configuration.instance
  end

  def core_indices
    @core_indices ||= indices.select(&:delta_processor).reject(&:delta?)
  end

  def delta_indices
    @delta_indices ||= indices.select &:delta?
  end

  def delta_indices?
    delta_indices.any?
  end

  def indices
    @indices ||= config.index_set_class.new :classes => [instance.class]
  end

  def new_or_changed?
    instance.new_record? || instance.changed?
  end

  def processors
    delta_indices.collect &:delta_processor
  end

  def suspended?
    ThinkingSphinx::Callbacks.suspended? || ThinkingSphinx::Deltas.suspended?
  end

  def toggled?
    processors.any? { |processor| processor.toggled?(instance) }
  end
end
```

Check for deltas at a higher level first.
user
```ruby
class ThinkingSphinx::ActiveRecord::Callbacks::DeltaCallbacks <
  ThinkingSphinx::Callbacks

  callbacks :after_commit, :before_save

  def after_commit
    return unless !suspended? && delta_indices? && toggled?

    delta_indices.each do |index|
      index.delta_processor.index index
    end

    core_indices.each do |index|
      index.delta_processor.delete index, instance
    end
  end

  def before_save
    return unless !ThinkingSphinx::Callbacks.suspended? && delta_indices? &&
      new_or_changed?

    processors.each { |processor| processor.toggle instance }
  end

  private

  def config
    ThinkingSphinx::Configuration.instance
  end

  def core_indices
    @core_indices ||= indices.select(&:delta_processor).reject(&:delta?)
  end

  def delta_indices
    @delta_indices ||= indices.select &:delta?
  end

  def delta_indices?
    delta_indices.any?
  end

  def indices
    @indices ||= config.index_set_class.new :classes => [instance.class]
  end

  def new_or_changed?
    instance.new_record? || instance.changed?
  end

  def processors
    delta_indices.collect &:delta_processor
  end

  def suspended?
    ThinkingSphinx::Callbacks.suspended? || ThinkingSphinx::Deltas.suspended?
  end

  def toggled?
    processors.any? { |processor| processor.toggled?(instance) }
  end
end
```
assistant