Deleted Index entry & Waste Space

Question

I'm reading OCP 11g Book(All-in-One exam guide by Oracle Press) in a chapter(Moving and reorganizing Data) it says..
Indexes do deteriorate as DML is executed: if a row is deleted, this will result in wasted space in the index. Oracle’s index maintenance algorithm does not permit reuse of this space. It is logically impossible to reclaim this space by relocating other
index keys because the index keys must always be stored in order ..and so on.
I've read (and tested) (courtesy Richard foote ) that index do use free space with subsequent insert whether or not the value is same. Richard foote has written it in 2009 in his blog post and the book seems to be of 2010 then why such misleading information from Oracle Press book?
Regards!!

Answer 1

Hi Fabricio
The point you're missing is that most indexes don't have space that needs to be reclaimed in the first place, as the deleted space is simply reused by subsequent inserts into the leaf block anyways. It's not true that "*Oracle’s index maintenance algorithm does not permit reuse of this space. It is logically impossible to reclaim this space by relocating other index keys because the index keys must always be stored in order*"
Not sure I'll be buying the book based on the little piece I've now read :)
Cheers
Richard Foote
http://richardfoote.wordpress.com/