Re[2]: OCP Question (Perf Tuning)

Tuesday, January 6, 2004, 1:59:26 PM, Mladen Gogala (mgogala_at_adelphia.net) wrote: MG> Nope. The answer is b). In the FIRST_ROWS mode, optimizer prefers NL to all other MG> methos despite the price.

Does Oracle themselves *document* that what you say is the case? I believe you, but I'm not sure that Oracle documents what you just said, so short of looking at the code, I'm not sure how anyone could be expected to really *know* what the answer to the original question was, which makes me wonder if the question is really even a fair question to ask.

Do we *know* that B is the case, or have we just always *observed* that it *happens to be* the case?

Best regards,

Jonathan Gennick --- Brighten the corner where you are http://Gennick.com * 906.387.1698 * mailto:jonathan@gennick.com

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MG> On 2004.01.06 13:44, Jay Wade wrote:
>> Hello:
>>
>> I was looking through some OCP questions posted on the web and came across
>> the one below.
>> I believe the answer is (D), because the join type would be dependent on the
>> number of rows within the table. Is this correct or does the OPTIMIZER_MODE
>> set to FIRST_ROWS alter this behavior?
>>
>>
>> The cost-based optimizer can choose between a nested loops join and a sort
>> merge join operation. All tables are analyzed and the OPTIMIZER_MODE is set
>> to FIRST_ROWS. Which execution plan will be the result?
>>
>> a. The sort-merge join.
>>
>> b. The nested loops join.
>>
>> c. This depends on some sort parameter values.
>>
>> d. This depends on the number of rows in each table.
>>
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MG> -- 
MG> Mladen Gogala
MG> Oracle DBA
MG> -- 
MG> Please see the official ORACLE-L FAQ: http://www.orafaq.net

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