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RE: Re[2]: undo tablespace

From: Fink, Dan <Dan.Fink_at_mdx.com>
Date: Wed, 29 Jan 2003 07:19:51 -0800
Message-ID: <F001.0053D4B2.20030129071951@fatcity.com>


Breno,

        100mb of redo in 20 minutes is not all that high. I have seen far worse (as I am sure most on the list have as well). Why do you perceive this as a problem? Are you seeing poor performance or waits?

        Is the generation of redo (and archived logs) causing the system to halt due to the archive_dump_dest filling up? If so, the problem is not the procedure, but rather the lack of proper process to manage your archive logs.

        Even with NOLOGGING, UNDO must be generated for read consistency, rollback and recovery. You are not inserting data into the undo tablespace. The undo entries are generated for each operation (insert/update/delete). However, the undo entry for an insert is very small and thus will consume very little undo space and redo.

        Don't concern yourself with trying to stop the generation of UNDO. You will end up causing yourself more problems that you will ever try to solve. It is part of the Oracle kernel and not modifiable (at least in this release). Focus on performance and decide if 100mb in 20 minutes is really a problem.

Dan Fink

-----Original Message-----
Sent: Wednesday, January 29, 2003 7:10 AM To: Multiple recipients of list ORACLE-L

Mike,

I asked it because I have a problem.
Any insert data in UNDO tablespace generate insert in REDO Files. Is is correct ?

When I execute a high procedure, many inserts in UNDO tablespace ocurres, so many inserts in REDO´s are genereate. I want to avoid this REDO´s generation.
My tables and indexes are in NOLOGGING, but I high value of REDO are generate (100 MB each 20 minutes). It is desnecessary.

Oracle 9i / NT

--

Breno A. K. Magnago
mailto:breno_at_mercantilsoares.com.br
Mercantil de Alimentos Soares

Wednesday, January 29, 2003, 10:29:15 AM, you wrote:

HMNI> Breno,
HMNI> There's no way to do this because it's the central pillar of Oracle's read
HMNI> consistency mechanism.
HMNI> It's possible to minimise or suppress redo but undo is out of your control.

HMNI> regards,
HMNI> Mike Hately

HMNI> -----Original Message-----
HMNI> Sent: 29 January 2003 11:39
HMNI> To: Multiple recipients of list ORACLE-L


HMNI> I have a high procedure (many INSERT's and UPDATE´s).
HMNI> This procedure generate insert's in UNDO TableSpace for rollback.
HMNI> I want to know if exists any way for don´t generate insert´s in UNDO HMNI> Tablespace.

HMNI> Oracle 9i / NT

HMNI> Thanks.

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--

Author: Breno A. K. Magnago
  INET: breno_at_mercantilsoares.com.br

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Author: Fink, Dan
  INET: Dan.Fink_at_mdx.com
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