
    if ! $Plans.key?("hub_adjust_del")
        $Plans["hub_adjust_del"] = 
            PL::Plan.new("delete from HSlot 
                            where hubname = $1 and slotno > $2",
                           ["varchar", "int4"]).save
        $Plans["hub_adjust_ins"] =
            PL::Plan.new("insert into HSlot (slotname, hubname, slotno, slotlink)
                            values ($1, $2, $3, $4)",
                            ["varchar", "varchar", "int4", "varchar"]).save
    end
    return if oldsl == newsl
    if newsl < oldsl
        $Plans["hub_adjust_del"].exec([name, newsl])
    else
        (oldsl+1).upto(newsl) do |x|
            $Plans["hub_adjust_ins"].exec(["HS.dummy", name, x, ""])
        end
    end
