Re: UNDO: 10g-style behaviour in

From: Randolf Geist <>
Date: Sun, 12 Apr 2009 03:12:14 -0700 (PDT)
Message-ID: <>

On Apr 11, 3:52 pm, "Jonathan Lewis" <> wrote:
> 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 where the tuned_undoretention dropped
> to a value much lower than their setting.  There particular circumstances
> made
> this a bit of a threat.


it's documented behaviour in 10g automatic undo tuning that if the available space in the UNDO tablespace is restricted (autoextend off), the UNDO_RETENTION parameter is simply ignored and tuned to whatever is possible given the space available and the current workload, so it can well go below the defined UNDO_RETENTION value.

See e.g. here:


Oracle related stuff blog:

SQLTools++ for Oracle (Open source Oracle GUI for Windows): Received on Sun Apr 12 2009 - 05:12:14 CDT

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