gistfile1.rb

    @search= ShippingItem.joins(:shipment => {:shipment_booking => {:dest_place => :address}}).
        departed.
        merge(Shipment.with_check_price_done).
        merge(Shipment.eta_in_prev_months 12).
        where(:unit_check_price.gt => 0).
        select('MAX(shipment_bookings.eta) AS latest_eta, shipping_items.item_variant_id AS latest_iv_id, addresses.country AS latest_country').
        group('shipping_items.item_variant_id, addresses.country').
        search(params[:search])
    @subquery = @search.relation.to_sql

    @shipping_items = ShippingItem.joins(:shipment => {:shipment_booking => {:dest_place => :address}}).
        joins("JOIN (#{@subquery}) ON item_variant_id = latest_iv_id AND eta = latest_eta AND country = latest_country").
        order_by_family_iv.
        includes(:item_variant => {:item_family => :category}, :shipment => [:forex_rates_bundle, :shipment_booking => {:dest_place => :address}]).
        page(params[:page])

I think we can just extract the shipping_item_ids from the subquery then just load them with second query. Adding an having clause should also yield the proper result without the need of a subquery...