uncommitted data in datafiles

Lets assume an update statement affects a large number of rows. There is no committ given for a very long time, assuming that there is no space in database buffer cache, these uncommitted data is propogated to the datafiles.

My question is



1. At some point of time these changed data in buffer cache will not be available. Since space has to be allocated for new data (Is my understanding Correct)

3. Where does this uncommitted data reside in the datafile.

2. Lets assume the user issues a committ statement after 3 days. WHat actually Happens ?. What happens to the data that is present as uncommitted data in the datafile. Also the buffers of this data is no more in the buffer cache. WIll it once again retrieve the old original data from the datafile ?????.


I hope my question is understandable, Please guys this concept is haunting me, help me out to understand.


Regards

Khan

I wouldsuggest having a read of Chapter 16 of the Concepts Guide, in aprticulari think your questions are anwered by this section