what factors need to be taken into account for doing bulk deleteBulk Delete

[pst]

First of all, I'd like to thank everyone for helping me in this site.

I have to do a set of bulk deletes, so could someone tell me what parameters or resources I need to take into account . I am told that normally it takes a lot of time. My database in noarchivelog mode.
Do I need to create a large rollback segment ?

pst.