Re: formula help please
From: DA Morgan <damorgan_at_psoug.org>
Date: Sun, 06 Jan 2008 02:02:35 -0800
Message-ID: <1199613731.373582@bubbleator.drizzle.com>
>
> Essentials in solving such problems ( as it seems for me) from Charles'
> post is:
> <quote>
> Oracle has no automatic understanding of how one table
> should be joined to another table, even if foreign keys are defined
> </quote>
> The only exception of this statement i am aware of (which is meaningless
> in this context, because you aren't using it - is natural join syntax).
> That means ( for me ) - if some tables are joined and cartesian product
> (leading to excessive row generation, cpu consumption and temp usage,
> what may appear as hang) should be avoided - then join conditions should
> be defined. Defining proper primary/foreign keys is not essential (but
> of course, may be helpful) to solve such problems...
>
> Best regards
>
> Maxim
Date: Sun, 06 Jan 2008 02:02:35 -0800
Message-ID: <1199613731.373582@bubbleator.drizzle.com>
Maxim Demenko wrote:
> Totti schrieb:
>> statments, and as i understood from you, the constraints and the >> primary and foreign keys are essentials in solving such problems.
>
> Essentials in solving such problems ( as it seems for me) from Charles'
> post is:
> <quote>
> Oracle has no automatic understanding of how one table
> should be joined to another table, even if foreign keys are defined
> </quote>
> The only exception of this statement i am aware of (which is meaningless
> in this context, because you aren't using it - is natural join syntax).
> That means ( for me ) - if some tables are joined and cartesian product
> (leading to excessive row generation, cpu consumption and temp usage,
> what may appear as hang) should be avoided - then join conditions should
> be defined. Defining proper primary/foreign keys is not essential (but
> of course, may be helpful) to solve such problems...
>
> Best regards
>
> Maxim
The other exceptions would be if you have defined BITMAP JOINS INDEXES or DIMENSION objects.
Consider, for example, the following syntax:
CREATE BITMAP INDEX bjix_fact_prod
ON facts (product.prod_name)
FROM facts, products
WHERE fact.prod_id = product.prod_id;
-- Daniel A. Morgan Oracle Ace Director & Instructor University of Washington damorgan_at_x.washington.edu (replace x with u to respond) Puget Sound Oracle Users Group www.psoug.orgReceived on Sun Jan 06 2008 - 04:02:35 CST