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From mike matrigali <mikema...@gmail.com>
Subject Re: Should the optimizer ever have a cost of "0.0"?
Date Tue, 27 Aug 2013 16:46:22 GMT
On 8/27/2013 9:43 AM, Rick Hillegas wrote:
> On 8/27/13 8:18 AM, Bergquist, Brett wrote:
>> I am just wondering if while the optimizer is producing a plan if a
>> cost of "0.0" should ever be seen.  Thinking naively, it seems to me
>> that all join plans and all access paths have some sort of cost which
>> should be greater than "0.0".   From my testing over the last few
>> days, when a plan comes up with a join such as "join T1 with T2" and
>> the T1 cost is "0.0", then this dominates the plan cost and even if
>> T2's access path is going to be a table scan of millions of rows, this
>> plan might be chosen.   This just does not seem right to me.
>>
>>
>>
>>
> Hi Brett,
>
> A scan cost of 0 sounds like a bug to me.
>
> Thanks,
> -Rick
>
I agree, seems like even a 0 row return scan should have some cost.

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