RE: Using DUAL

I was not directly involved with that particular discussion. But one of the things that I remembered (and played with, not in production yet!) is to create 'dual' as a view using 'select dummy from x$dual;' This causes less number of Logical IOs. In addition, creating an index on dummy can also help. I have not tested that part yet. Cary Millsap mentioned it in one of his e-mails. From what I understand the nunber of LIOs is Oracle version dependent and 9i uses the least. Gaja had suggested to recreate 'dual' as an IOT. Anjo Kolk mentioned that Oracle has been using x$dual in RMAN code.

HTH,

• Kirti

-----Original Message-----
Sent: Thursday, May 30, 2002 12:49 PM
To: Multiple recipients of list ORACLE-L

Dan:
The discussion was recent, but I cannot find reference to it. I kinda thought Kirti was involved in the thread, and it had something to do with creating an x$dual table as a workround to hammering dual.

Sorry I can't remember any more . . .

Barb

> ----------
> From: Fink, Dan[SMTP:Dan.Fink_at_mdx.com]
> Reply To: ORACLE-L_at_fatcity.com
> Sent: Thursday, May 30, 2002 10:23 AM
> To: Multiple recipients of list ORACLE-L
> Subject: Using DUAL
>
> The developers here have a fondness for using DUAL for simple operations
> (select count(*) from dual is executed 10000+ times per day). I recall a
> passing comment somewhere/sometime that there are performance issues with
> accessing DUAL. Of course, now that I need to provide some information to
> the developers, I can't recall the comment or find documentation.
>
> Any assistance is greatly appreciated.
>
> Daniel W. Fink
>
>

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