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Re: DML on dual?

From: John Darrah <darrah.john_at_gmail.com>
Date: Thu, 12 Apr 2007 12:44:44 -0600
Message-ID: <ec40ac060704121144r6bdb2c46h9b000c64127d48f@mail.gmail.com>


Looks like this was something sqlplus did until version 10.2 to check if the database was read only or not. From a note I found on metalink:

In 9.0 SQLPLUS was altered to issue an "select null from dual for update nowait"
statement to check if the target database is READ ONLY. This is no longer required for 9.2 database and so SQLPLUS should no longer issue this SQL.

The doc says it was fixed in 10.2

Thanks
John

On 4/12/07, Herring Dave - dherri <Dave.Herring_at_acxiom.com> wrote:
>
> Good call! I didn't see this previously, but then again I didn't search
> for it specifically:
>
> LAST_LOAD_TIME LOADED_VERSIONS OPEN_VERSIONS
> EXECUTIONS FIRST_LOAD_TIME CPU_TIME
> ------------------- ------------------ ------------------
> ------------------ ------------------- ------------------
> ELAPSED_TIME
> ------------------
> SQL_TEXT
>
> ------------------------------------------------------------------------------------------------------------------------------------
> 2007-04-12/08:59:30 1 1 927
> 2007-04-06/20:30:02 352600
> 539648
> SELECT NULL FROM DUAL FOR UPDATE NOWAIT
>
> I also now have the userid that generates these. At least now I
> know. Thanks again.
>
> Dave
>
>
> ___________________________________
> David C. Herring, DBA| A c x i o m Delivery Center Organization
> 630-944-4762office |630-430-5988 wireless|630-944-4989 fax
> ________________________________________
> From: John Darrah [mailto:darrah.john_at_gmail.com]
> Sent: Thursday, April 12, 2007 1:20 PM
> To: Herring Dave - dherri
> Cc: oracle-l_at_freelists.org
> Subject: Re: DML on dual?
>
> I've seen several oracle trace files that have the statement "SELECT 1
> FROM DUAL FOR UPDATE NOWAIT" I have no idea what the purpose of that
> statement is but it probably explains what you are seeing.
>
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Received on Thu Apr 12 2007 - 13:44:44 CDT

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