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Re: why undo_management=auto

From: Andy Hassall <andy_at_andyh.co.uk>
Date: Fri, 22 Dec 2006 18:13:22 +0000
Message-ID: <ks7oo2p3ejk9dubmq3ghahf8aapjb3q7c2@4ax.com>


On Thu, 21 Dec 2006 18:14:06 -0800, DA Morgan <damorgan_at_psoug.org> wrote:

>Andy Hassall wrote:
>> On Thu, 21 Dec 2006 14:56:12 -0800, DA Morgan <damorgan_at_psoug.org> wrote:
>>
>>> I just went into the docs:
>>> http://download-west.oracle.com/docs/cd/B19306_01/server.102/b14231/create.htm#sthref413
>>> and found an error I just reported. Where what is written is: "By
>>> default, this parameter is set to MANUAL."
>>
>> What makes you think this is a documentation error?
>
>Your question got me to thinking and now I'm more confused than ever
>(and that takes a bit of doing).
>
>Here's what the Oracle doc says:
>"The UNDO_MANAGEMENT initialization parameter determines whether an
>instance starts in automatic undo management mode which stores undo in
>an undo tablespace. By default, this parameter is set to MANUAL. Set
>this parameter to AUTO to enable automatic undo management mode."
>
>This would indicate that undo tablespace is NOT the default and requires
>manual intervention.
>
>And this query:
>
>SQL> SELECT name, value, isdefault
> 2 FROM gv$parameter
> 3 WHERE name LIKE '%undo%';
>
>NAME VALUE ISDEFAULT
>------------------------------ ------------------------------ ---------
>undo_management AUTO FALSE
>undo_tablespace UNDOTBS1 FALSE
>undo_retention 3600 FALSE
>
>Would tend to confirm that AUTO is not the default.

 Yep.

 Also try the following; start up the database with the undo_management parameter missing completely - you'll find it's MANUAL.

>Except that I just built a 10g database and there is no question that
>the value defaulted to AUTO and the database has an UNDO tablespace.

 What did you create it with? DBCA defaults to setting it to AUTO, but this is a non-default value from Oracle's point of view.

-- 
Andy Hassall :: andy@andyh.co.uk :: http://www.andyh.co.uk
http://www.andyhsoftware.co.uk/space :: disk and FTP usage analysis tool
Received on Fri Dec 22 2006 - 12:13:22 CST

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