Re: datawarehouse explain plan question

From: Doug Cowles <dcowles_at_bigfoot.com>
Date: Wed, 19 May 1999 13:51:01 -0400
Message-ID: <3742FA04.CA184AF5@bigfoot.com>

Thanks for the info. Someone wanted to know where this article was and I got in from a 1 credit class so I'm not sure, but I assume it was from Oracle Magazine. The essense of the article was that with the star hint the dimension tables would be joined first into a virtual table containing the values of the composite index for the fact table in preparation for one pass through it. It is dated October 1996. If anyone knows where to get back issues of Oracle Magazine I would be curious as well.

Jonathan Lewis wrote:

> This is just a detail of terminology A range scan is an index scan
> that is capableof returning several rows, even if the scanis performed
> on a unique index. The only way to get a UNIQUE SCAN is tosupply all
> columns of the index in orderto guarantee a single row will be
> returned.
>
> --
>
> Jonathan Lewis
> Yet another Oracle-related web site: www.jlcomp.demon.co.uk
>
> My understanding was that as long as you referenced columns
> in a left-wise fashion
> on a composite index, you could still get a UNIQUE scan.
>
>
>
Received on Wed May 19 1999 - 12:51:01 CDT