[Zope] how to search entire site from a sub dir?

I have a zope the dirctory structure is Root ->sub1f1->sub2f1->sub3f3 ->sub1f2 ->development->sundev->mydev I need to search entire site from mydev, i am trying to use Zcatalog to do it but after i created A zcatalog under mydev, i use find objects to put object to ZODB. but i can not find a way to seach the entire site, is there a way to do that? Thanks