Re: Rule vs. Cost

Jim,

We have Oracle v7.3.4.x here and everytime we try and go to cost base, everything just gets dragged down the tube, and we have indexes, primary keys, foreign keys with child indexes. Now, with that said, I do believe that we need more education on the matter before we can say that there is something wrong with v7's optimizer, but we have had no luck with it so far.

HTH Karl Nordquist
Application Development Supervisor
Bright Wood Corporation
Madras, OR
karln_at_brightwood.com

jawa wrote:

> Rule-based optimization runs more efficiently than cost on our application.
> The supplier told us that the version 7 optimizer has problems. Is this
> true, or is it that their application was not written by folks knowledgeable
> of the hints and tricks designed to take full advantage of cost-based
> optimization? For instance, I ran a small benchmark report on the schema
> and found: (1) >40 tables with no index on them at all (even small tables
> without an index become the driving table), and (2) >100 foreign keys
> missing child index references (all having the potential to put locks on the
> parent table). Could these contribute to a cost-based scenario that would
> perform poorly, or is it true that version 7's optimizer has problems like
> the supplier alleges? Has anyone else experienced a similar case study?
>
> --
> Jim Wadas
> Information Technology Solutions and Services (ITSS)
> Motorola Systems Solutions Group (SSG)
> Scottsdale, AZ 85257
> (480) 441-8196
> Jim.Wadas_at_motorola.com
Received on Tue Nov 09 1999 - 11:11:43 CST