Re: Why does a datafile extend a very large amount at very infrequent intervals?

From: Hemant K Chitale <hemantkchitale_at_gmail.com>
Date: Fri, 12 Oct 2012 09:44:58 +0800
Message-ID: <CAMNBsZsnatVY3dmLQUxqU7hYa5+nj-bMYKexDNi0ip1z1x+z9A_at_mail.gmail.com>



Thanks for this note.
I had upgraded a database from 11.1.0.6 to 11.2.0.3 I then noticed the datafiles extending significantly more than expected.  It is a sort of a datawarehouse where there are DROP and TRUNCATE and CREATE commands.
Once I set autoextend OFF on the datafiles, the growth of the datafiles stopped.

Hemant

On Wed, Jul 11, 2012 at 7:21 AM, Rich <richa03_at_gmail.com> wrote:

> [removing the rest of the email chain to prevent getting over-quoting]
> Finally found the answer to this one (with no help from Oracle Support) -
> it's due to the new [in 11g] Oracle process ora_smco.
> This process "performs tablespace-level space (extent) pre-allocation".
>
> This is noted in Oracle Note 743773.1 (last modified 13APR2012).
>
>
> Another thing to potentially note about this is that this process spawns
> slave processes (ora_w###).
>
> On our instance, we also see these processes consuming more CPU time than
> expected - this is bug 12760469: STBH: KTSJ USES CONSIDERABLE AMOUNT OF
> DATABASE TIME/CPU RESOURCE.
>
> This bug is supposed to be fixed in 11.2.0.4.
>
> Rich
>
> Including keywords such that a search will hopefully find this:
> NEXT_EXTENT DBA_DATA_FILES INCREMENT_BY
>
>
> --
> http://www.freelists.org/webpage/oracle-l
>
>
>

-- 

Hemant K Chitale


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Received on Fri Oct 12 2012 - 03:44:58 CEST

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