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Performance Issue [message #10277]

Mon, 12 January 2004 21:31

Developer
Messages: 19
Registered: January 2004

Junior Member

Hi!

Is there any kind of difference between these two quiries

1)
select e.empno
from emp e, dept d
where e.deptno = d.deptno

2)
select e.empno
from emp e, dept d
where d.deptno = e.deptno

regards

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Re: Performance Issue [message #10279 is a reply to message #10277]

Mon, 12 January 2004 22:49

Maaher
Messages: 7065
Registered: December 2001

Senior Member

No.

MHE

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Re: Performance Issue [message #10281 is a reply to message #10279]

Mon, 12 January 2004 23:03

resy
Messages: 86
Registered: December 2003

Member

Yes. Ofcourse there is no difference in output.
But it is always a good practice that use the table name which has more records in left side of where condition.

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Re: Performance Issue [message #10284 is a reply to message #10281]

Tue, 13 January 2004 01:43

Maaher
Messages: 7065
Registered: December 2001

Senior Member

Wasn't the question. In fact, it used to be good practice to put the driving table last in the table list, and in the left parts of the select.

But Oracle's optimizer has gone beyond that need.

MHE

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Oops [message #10295 is a reply to message #10284]

Tue, 13 January 2004 20:36

Maaher
Messages: 7065
Registered: December 2001

Senior Member

Typed too fast: should (of course) be:
...it used to be good practice to put the driving table last in the table list, and in the left parts of the where clause equasions.

MHE

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Re: Performance Issue [message #10339 is a reply to message #10277]

Thu, 15 January 2004 06:01

Thiru
Messages: 1089
Registered: May 2002

Senior Member

See here --> Joins
and
Join Order

-Thiru

[Updated on: Fri, 18 February 2005 23:32]

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