Posted by Tony Rogerson on 04/13/06 20:24

Might be aluding to this....

SELECT 1 FROM ACTIVITY_ENTRY WHERE (1=0) FOR UPDATE

Which Oracle gives a table / index scan rather than realising it doesn't
need to do anything.

--
Tony Rogerson
SQL Server MVP
http://sqlserverfaq.com - free video tutorials

"Serge Rielau" <srielau@ca.ibm.com> wrote in message
news:4a6vb6FrjsldU1@individual.net...
> DA Morgan wrote:
>> That's what I've done. I've never seen it. But running SELECT 1 may be
>> more of a test of how clueless the person doing the test is than of the
>> hardware and operating system. As the two events are not at all similar
>> in what they do.
> Rating high on the cluelessness on SELECT 1 myself, would you care to
> elaborate?
> My working hypothesis is that SELECT 1 returns a result set of one row and
> one column to the client.
> So does SELECT 1 FROM DUAL, AFAIK.
> If you are alluding to the fact that Oracle may actually do a table lookup
> on DUAL then that could hardly be the competitions fault and you would be
> free to supply a better approach for how to return a result set without
> driving IO.
>
> Cheers
> Serge
> --
> Serge Rielau
> DB2 Solutions Development
> IBM Toronto Lab

[Back to original message]