Re: Rule vs. Cost

Jim,

V7 optimizer makes no use of CPU as a metric, this is added in V8, which could be a problem ?

The use of (CBO)and hints in an 3rd-party application needs to be implemented in such a way that they can be changed to suit the growth of the database. Such flexibility is always hard to implement.

There will become a time when the rules need to be broken, ask your supplier how they would resolve this...

Chris.

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 Mon Nov 08 1999 - 16:30:40 CST