Re: Cost based optimizer

>
> It talked about adding "hints" to SQL statements that were using the Cost
> based optimizer.
>
 

>
> So if you add hints to SQL statements that use cost based optimization (and
> collect statistics), what is the advantage of cost based over rules based
> optimizer ????????????
>
> Thanks to anyone who can give me insight on this subject.
>
> Art

Art,
unfortunately the COST based optimizer is not AI based or all knowing, insteadit seems it has a set of rules it follows. As a result it still makes assumptions or middle of the road assesments. It is always best that the Application Developer has hints or documents their code. But in most cases the DBA is left to figure it out.

So even though the COST based optimizer is automagic, it is still best to have hints in your code.

Steve Lemme
DBA
Motorola

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