Update and pruning

[Jens Tandstad]

I have a very straightforward question:
I have table partitioned by parentID. If I change the parentID and the new parentID requires the row to be moved to a different partition. Does this happen automatically if i use the SQL below?

UPDATE person.parentID = 22 where parentID = 10;

Does the system identify if the row is now in violation with the partition it is currently in, and move it? If yes, is the previous partition reordered (defragmented) or is there an empty row in it? And is there a defragmentation function for this kind of situtation that can be scheduled for running during the night. I have a system where that requires fast access to data (pruning helps) but it also requires a great deal of updating.

I am grateful for any help.
Regards
Jens