Re: select value within an interval
- From: DA Morgan <damorgan@xxxxxxxxx>
- Date: Wed, 19 Apr 2006 09:33:25 -0700
Vladimir.Usov@xxxxxxxxx wrote:
Hi Daniel
Well the goal is to create an efficient SQL :-) that requires minimum
of consistent gets.
I need to get a product type from range of products based on particular
product id.
It is like salary table in Oracle HR Demo Scheme that stores salary
ranges and if I want to report to manager salary grade I have to select
emp.salary between low_value and high_value.
Any idea why Oracle reads the whole table or does index FFS if I use
INDEX hint?
Does Oracle have problem with such selects?
Regards
Vladimir
Oracle doesn't "have a problem" but you seem to be making the assumption
that reading the whole table is a bad idea. Might be ... might not be.
The optimizer, based on the information it has available, certainly
thinks it is taking the lowest cost path. I don't see any history of
this thread above so it is hard to be too specific but I would suggest
two things:
1. Explain Plan
2. If you are going to hint "fully" hint as recommended by Jonathan Lewis.
Be sure that the information you are providing to the optimizer is what
it needs to make a good decision.
--
Daniel A. Morgan
http://www.psoug.org
damorgan@xxxxxxxxxxxxxxxx
(replace x with u to respond)
.
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