return me the paper after 2000 in VLDB conference with the most citations . 
return VLDB conference ;return #1 after 2000 ;return papers of #2 ;return citations of #3 ;return number of  #4 for each #3 ;return #3 where #5 is  highest
['select', 'filter', 'project', 'project', 'group', 'superlative']