Re: RULES vs. COST

dischner_at_med.uni-muenchen.de (Anton Dischner) wrote:
>In article <3havdo$91b_at_ams.amsinc.com>, Edward_Hillman_at_mail.amsinc.com (Ed
>Hillmann) wrote:
>
>> Hi folks. I'm trying to gather opinions and guesses about Oracle7's
>> optimization
>> options, and what currently is the best setup.
>>
>> My understanding is this: Oracle has always used a RULES-based system.
>> Oracle7 now has both a COST-based as well as RULES-based system.
 

>Correct
 

>> These are what I have heard...and please feel free to shoot holes in them if
>> they're not right:
>>
>> - RULES-based optimization will not be supported by Oracle in the next few
>> years.
 

>Yes, Oracle's written statement.
 

>> - The current COST-based system is not working 100%, ie. the optimal execution
>> plan is not always chosen,
 

>Yes, this is correct

our experiance is that COST does not work at all - were waiting for 7.1 with interest.

>> - When the RULES-based system is no longer supported by Oracle, they will
>> have made modifications to the COST-based system, so that the parser will
>> choose the correct path, no matter how the query was originally optimized.
 

>I hope so, i don't believe it!
>I think we will have to hassle around with compiler hints (doing optimization
>on our own :-().

>>
>> I was wondering if anyone had any opinions on which is currently the best
>> setup (RULES vs. COST), based on any experience. I keep hearing adament
>> defenses of both systems, so I figure the more the merrier. :)

RULES is what our Guru sugests
.

|Maurice Walshe               You'll Never Get to heaven with an Ak47,       |
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