Re: Concept Question --- Redo Log Recycle

I take that back. I seem to remember that it will still write to the online redo log files ... but only put an SCN when you tell it to commit.

>
> Since you mentioned no commits are happening, LGWR only writes to the
online
> redo log when you tell it to commit. Here is the quote from the Oracle
> documentation:
>
> "Redo records are buffered in a circular fashion in the redo log buffer of
> the SGA and are written to one of the online redo log files by the Oracle
> background process Log Writer (LGWR). Whenever a transaction is committed,
> LGWR writes the transaction's redo records from the redo log buffer of the
> SGA to an online redo log file, and a system change number (SCN) is
assigned
> to identify the redo records for each committed transaction. Only once all
> redo records associated with a given transaction are safely on disk in the
> online logs is the user process notified that the transaction has been
> committed."
>
> Thus, in your case, I presume the redo records are still in the redo log
> buffer of the SGA ( not yet recorded the actual online redo log FILES ).
>
> >
> > System crashes now.
> >
> > So what happens after instance is back up ?
> > Since the redo logs have been reused....
> > How exactly does Oracle roll-forward and undo the
> > UNCOMMITED changes to the disk ?
> > Read from RBS ?
> >
> > Pls be as specific as u possibly can.
> > Really appreciated !
> >
> > jane
> >
> >
> >
> >
> >
> >
>
>
Received on Fri Nov 23 2001 - 00:31:43 CST