Re: are hints still necessary in 9i?

on 10/9/2003 1:01 PM Jonathan Lewis said the following:

>But how are Profiles different from Outlines ?
>
>

Major difference is that Outlines freezes a particular plan and Profiles dont. Also, the way I see, Profiles are 'automatic' (generated by the SQL Tuning Advisor (new in 10g) that runs the optimizer in a 'Tuning' mode and gives it more time to find a very good plan) and Outlines are 'manual'.

>And what is the cost of enabling a few profiles
>for a few special SQL statements when 99%
>of your code does not need profiles ?
>The second question is more important than the
>first - there is always a cost/benefit trade in a
>feature like this.
>

Thats exactly true. But, its a bit too early to start making about the cost of enabling new 10g features isn't it?

-V

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>
>Jonathan Lewis
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>
>>Forgive me for not exactly sticking with the subject that goes "are
>>
>>
>hint
>
>
>>necessary in *9i*". In 10g, we have "SQL Profiles" which exactly is
>>
>>
>a
>
>
>>set of such information which Tom calls "good hints", that guides
>>
>>
>the
>
>
>>optimizer to do the right thing rather than forcing the optimizer to
>>make a particular decision. Even better, one can create SQL Profiles
>>
>>
>for
>
>
>>any SQL, no matter they are from packaged apps or custom apps
>>
>>
>without
>
>
>>modifying the actual SQL statement. Simply, starting from 10g, I see
>>
>>
>no
>
>
>>future for any type of hints - no matter whether they are the
>>
>>
>"good"
>
>
>>ones, or the "bad" ones or the "ugly".
>>
>>Thanks,
>>-V
>>
Received on Thu Oct 09 2003 - 19:26:27 CDT