Re: Thank you Oracle Support - cursor_sharing = similiar is deprecated!

• Exact sharing for the columns histogram.
• Exact sharing for the columns used as range predicates(between, >=, >, <=, <, ...)
• Force sharing for the columns none of aboves

Similar sharing with the histogramed-columns and/or ranged-columns would generate tons of child cursors and reparse would occur for each child cursor.

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2010/11/30 Ram Raman <veeeraman_at_gmail.com>

>
> Thanks for the pointer Carol.
>
> I was reading up on the ML note and I saw this: "This parameter is
> generally overly restrictive in what it actually allows to be shared.
> SIMILAR tells oracle to try and share cursors by replacing all literals with
> binds for legacy applications, but directs that sharing only be performed
> when all the replaced literal values were exactly the same (in the case of
> predicates referencing columns with histograms or using inequality operators
> such as BETWEEN, <, and !=) "
>
> I am confused by what "but directs that sharing only be performed when all
> the replaced literal values were exactly the same" means. I thought SIMILAR
> would make Oracle use the already existing plan without having to reparse in
> case of **different** literal values. Is that the right understanding of
> 'sharing of the cursor' ? If sharing is performed only when replaced literal
> values are the exactly same, wouldnt that make it EXACT and not SIMILAR?
>
> Thanks.
>
> 2010/11/25 <Laimutis.Nedzinskas_at_seb.lt>
>
>> nice, one more AI decoration gone.
>>
>>
>>
>> ---------------------------------------------------------------------------------
>>
>> Please consider the environment before printing this e-mail
>>
>>
>>
>> Carol Dacko
>> <dackoc_at_gmail.com
>> > To
>> Sent by: Oracle-L Freelists
>> oracle-l-bounce_at_f <oracle-l_at_freelists.org>
>> reelists.org cc
>>
>> Subject
>> 2010.11.23 18:49 Thank you Oracle Support -
>> cursor_sharing = similiar is
>> deprecated!
>> Please respond to
>> dackoc_at_gmail.com
>>
>>
>>
>>
>>
>>
>>
>>
>> Maybe I am the last person to the know but Doc ID: 1169017.1 is the
>> announcement that cursor_sharing = similar is now deprecated in 11g! And
>> the write up is very good. And it is great that they also included in the
>> references the Optimizer Team's blog about it too.
>>
>> So yes, thank you Oracle Support! I really do appreciate this! This will
>> now be one more battle I don't need to fight!
>>
>> Warm regards,
>> Carol Dacko
>> University of Michigan
>>
>>
>>
>> --
>> http://www.freelists.org/webpage/oracle-l
>>
>>
>>
>

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