Re: why undo_management=auto

DA Morgan wrote:
> aman.oracle.dba wrote:
> > Hello ALL,
> >
> > according to
> > http://www.lc.leidenuniv.nl/awcourse/oracle/server.920/a96521/undo.htm#9114
> > the use of rollback segments for managing undo space will be deprecated
> > in a future release.
> > WHY....................
> > what are the main advantages to keep separate undo_tablespace in
> > database, when I can make one separate tablespace for rollback segments
> > also.
>
> Not that far into the future ... as of 10g they are gone.
>
> Why?
>
> Partially to put an end to ORA-01555, partially because DBAs have proven
> themselves incapable of managing rollback segments, and partially
> because the new algorithm improves many aspects of database existance
> and makes possible some aspects of flashback technology.
>
> It would seem that Oracle has taken the same attitude toward rollback as
> they have taken toward temp ... we can do it better than you can. <g>
> --
> Daniel A. Morgan
> University of Washington
> damorgan_at_x.washington.edu
> (replace x with u to respond)
> Puget Sound Oracle Users Group
> www.psoug.org

Are you sure that they are gone?

Oracle Database Administrator's Guide 10g Release 2, Page xlv: "Deprecation of use of rollback segments (manual undo management mode) Manual undo management mode has been deprecated and is no longer documented in this book. Use an undo tablespace and automatic undo management instead.
See Chapter 10, Managing the Undo Tablespace"

Page 10-2
"You set the UNDO_MANAGEMENT initialization parameter to AUTO to enable automatic
undo management. A default undo tablespace is then created at database creation. An
undo tablespace can also be created explicitly. The methods of creating an undo
tablespace are explained in "Creating an Undo Tablespace" on page 10-6."

"UNDO_MANAGEMENT If AUTO, use automatic undo management. The default is MANUAL." It appears that in 10g R2, rollback segments are deprecated, no longer documented in the Administrator's Guide, yet are still the default based on the default value of UNDO_MANAGEMENT. Did I read something wrong?

Charles Hooper
PC Support Specialist
K&M Machine-Fabricating, Inc. Received on Thu Dec 21 2006 - 15:22:34 CST