Lucene Grouping problem

Hi,there.I meet a problem to grouping the search result by time span and/or web site.Can Lucene's
FirstPassGroupingCollector and SecondPassGroupingCollector work.Is there search performance
problem under oceans of datas?  Is is possible to group based on all Docs not top DOcs?Thanks guys/girls.

--

____________________________________________
齐保元(Qi Baoyuan)
中科院计算技术研究所 智能信息处理重点实验室(ICT,NKI,GUCAS,Beijing,China)
手机：15120084688
E-Mail：qibaoyuan <at> 126.com