Re: UNDO: 10g-style behaviour in

From: Randolf Geist <>
Date: Mon, 13 Apr 2009 12:51:43 -0700 (PDT)
Message-ID: <>

On Apr 13, 10:16 am, "Jonathan Lewis" <> wrote:
> Randolf,
> Thanks for supplying a couple of references.
> My comment was specifically in response to this point, though:
>     "In the AutoExtend ON case, the value you set for "undo_retention" is
>      the floor value but Oracle automatically adjusts the actual
>      undo_retention it uses on the basis of query durations"
> i.e. the case when AutoExtend is ON - and my point was that I had seen
> the tuned_undoretention  value in v$undostat drop BELOW the setting
> for parameter undo_retention with autoextend ON.


apologies, I got that wrong and thought it was about the "autoextend OFF" case. Your case seems to be odd, yes, and I would tend more to the "implementation bug" or "implementation limitation" explanation (given the "all available space tied to one large undo segment" information).

By the way, I thought that I've seen TUNED_UNDORETENTION in V$UNDOSTAT larger than UNDO_RETENTION with AUTOEXTEND = ON with long running queries, but I'm not entirely sure and therefore it might be wrong.


Oracle related stuff blog:

SQLTools++ for Oracle (Open source Oracle GUI for Windows): Received on Mon Apr 13 2009 - 14:51:43 CDT

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