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RE: undotbs01.dbf just keeps growing

From: John Dunn <john.dunn_at_sefas.co.uk>
Date: Tue, 06 Jan 2004 00:54:26 -0800
Message-ID: <F001.005DBBC9.20040106005426@fatcity.com>


Daniel

How can i use the v$undostat.maxquerylen value to configuure the undo tablespace?

Also, how can I tell what the longest transaction is actually doing?, i.e what sql is being run?

John

-----Original Message-----
Sent: 05 January 2004 17:54
To: Multiple recipients of list ORACLE-L

Jared,

It sure is nice to be missed. I'll make sure my secretary calls you about my future vacation plans...:)

You've nailed the problem. Autoextend, automatic undo and high undo retention is
a recipe for high disk usage. The aum algorithm is such that preference is given
to extending over reuse (especially since expire time propogation is a problem).

In order to find the length of the longest transaction, reference the v$undostat.maxquerylen value. Beware as there are known bugs with this view, so
examine the output carefully to make sure it makes sense.

Daniel Fink

Jared Still wrote:

> The data file(s) for your undo tablespace is likely set
> as autoextend with an unlimited size.
>
> Run the attached script to check it.
>
> If so, you can use this to put a limit on it:
>
> alter database datafile '<your file name>' autoextend on next 200m
> maxsize 2000m;
>
> Adjust the numbers for your system.
>
> You should probably investigate why it continues to grow so large.
>
> I haven't yet converted our production databases to UNDO, having
> only recently migrated to 9i, so I don't have any useful advice
> past this.
>
> There are others that will be able to offer more for this. ( Dan
> Fink, where are you? This might even get Kirti to take a break
> from his book for a few minutes )
>
> HTH
>
> Jared

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Daniel Fink
  INET: Daniel.Fink_at_Sun.COM

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Received on Tue Jan 06 2004 - 02:54:26 CST

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