Re: UNDO: 10g-style behaviour in 9.2.0.8?

"Hemant K Chitale" <hemantkchitale_at_gmail.com> wrote in message news:5e7ad83e-61a2-4d9d-849b-b29235fc7706_at_c9g2000yqm.googlegroups.com...
> Yes, there is one significant difference (other than Retention
> Guarantee)
>
> It is called "Automatic Undo Retention" . Automatic Undo Management
> behaviour differs depending on whether the datafiles in the Undo
> tablespace are set to AutoExtend ON or AutoExtend OFF.
> In the AutoExtend ON case, the value you set for "undo_retention" is
> the floor value but Oracle automatically ajdusts the actual
> undo_retention it uses on the basis of query durations -- this you
> will see in MAXQUERYLEN and and TUNED_UNDORETENTION in V$UNDOSTAT.

I can't recall seeing anything that says the value you set is the floor value -
a reference would be useful as I've had one client run into problems with automatic undo retention in 10.2.0.3 where the tuned_undoretention dropped to a value much lower than their setting. There particular circumstances made
this a bit of a threat.

-- 
Regards

Jonathan Lewis
http://jonathanlewis.wordpress.com

Author: Cost Based Oracle: Fundamentals
http://www.jlcomp.demon.co.uk/cbo_book/ind_book.html

The Co-operative Oracle Users' FAQ
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