PAVB, I called the thing "white space" because I accept and use TK´s definition of fragmentation (showed in http://asktom.oracle.com/pls/asktom/...19043139891434 ) : 'space IMPOSSIBLE to reuse in normal DML operations', ie, extents with different sizes (the db cannot "break" extents in smaller parts), this kind of space yes, NEVER will be reused. My case is different, eventual DMLs ** will ** use my now-empty space normally.no fragmentation properly saying here...
Bore, I will try the Segment Advisor, but according to the manual (Oracle® Database Administrator's Guide, chapter 14 "Managing Space for Schema" :

"The Segment Advisor generates the following types of advice:

If the Segment Advisor determines that an object has a significant amount of free space, it recommends online segment shrink. If the object is a table that is not eligible for shrinking, as in the case of a table in a tablespace without automatic segment space management, the Segment Advisor recommends online table redefinition.

If the Segment Advisor encounters a table with row chaining above a certain threshold, it records that fact that the table has an excess of chained rows
"

row chaining, of course, don´t matters in the context what we are talking, my doubt is : what is "a significant amount" ? What is the algorithm ? Is it based in extent size, or it does the same as me (ie, compares number of rows with number of blocks) or what ? It covers my situation, in a word ?

Regards,

Chiappa