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"Pradeep" <agarwalp_at_eeism.com> wrote in message
news:1134574000.974721.270670_at_g43g2000cwa.googlegroups.com...
> Thought of this situation while going through one of the threads on
> asktom on checkpoint.
> Suppose
> - uncommitted data is flushed to the disk and
> - corresponding rollback is also flushed
> - corresponding redo is later overwritten
> - instance crash.
>
> How does it recover now ?? or how does is rollbacks the uncommitted
> data that is on the disk.
>
If the transaction is uncommitted, then the rollback will be held open, and cannot be overwritten (undo segment header will have a transaction table slot in state 10).
In the event of a crash, any redo that has to be re-applied will still leave the transaction visible as an uncommitted transaction in the rollback segment header.
So the transaction will be rolled back.
-- Regards Jonathan Lewis http://www.jlcomp.demon.co.uk/faq/ind_faq.html The Co-operative Oracle Users' FAQ http://www.jlcomp.demon.co.uk/cbo_book/ind_book.html Cost Based Oracle: Fundamentals http://www.jlcomp.demon.co.uk/appearances.html Public Appearances - schedule updated 29th Nov 2005Received on Wed Dec 14 2005 - 10:08:47 CST