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CBO [message #617840] Thu, 03 July 2014 22:51 Go to next message
balaji123
Messages: 29
Registered: October 2009
Location: sanfrancisco
Junior Member
This question is related to CBO ( Cost based optimizer)

select a.*,b.* from a,b
where a.emp_no = b.emp_no +0
and a.dept_no = b.dept_no + 0
and a.sal > 3000 OR a.sal > 5000

toad optimizer suggested to use + 0 on sql where condition.
Please advise. +0 means ignoring index ?

Thanks in advance.

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Re: CBO [message #617854 is a reply to message #617840] Fri, 04 July 2014 01:33 Go to previous messageGo to next message
Michel Cadot
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Location: Nanterre, France, http://...
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TOAD is dumb.
It is something we did with RBO to prevent the usage of an index.
It is stupid with CBO.
Throw away this tool, it is b...

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Re: CBO [message #617856 is a reply to message #617840] Fri, 04 July 2014 01:35 Go to previous messageGo to next message
John Watson
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Registered: January 2010
Location: Global Village
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It looks to me as though that is indeed an attempt to suppress index usage. One of the most stupid constructs I have seen.

Stamp out toads Mad

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Re: CBO [message #618019 is a reply to message #617856] Sun, 06 July 2014 21:44 Go to previous messageGo to next message
balaji123
Messages: 29
Registered: October 2009
Location: sanfrancisco
Junior Member
Thank you so much for the response.
Is there any specific free oracle sql optimizer tool available in the market ? Please advise.

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Re: CBO [message #618030 is a reply to message #618019] Mon, 07 July 2014 00:14 Go to previous messageGo to next message
Michel Cadot
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No.

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Re: CBO [message #618468 is a reply to message #618030] Sat, 12 July 2014 03:41 Go to previous messageGo to next message
rc3d
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Do you speak about http://www.quest.com/sql-optimizer-for-oracle/ SQL Optimizer for Oracle?

Which means this function is not included in "normal" Toad?

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Re: CBO [message #618470 is a reply to message #618468] Sat, 12 July 2014 04:04 Go to previous message
Lalit Kumar B
Messages: 3174
Registered: May 2013
Location: World Wide on the Web
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rc3d wrote on Sat, 12 July 2014 14:11
Do you speak about http://www.quest.com/sql-optimizer-for-oracle/ SQL Optimizer for Oracle?

Which means this function is not included in "normal" Toad?


All these are just going to develop more bad practices. Oracle provides lot of features for identifying performance bottlenecks, all it needs is to learn the techniques and gain knowledge to use them. And especially during learning stage a developer must not depend on such tools, rather spend some time to read, learn and understand the concepts and techniques. Which will be useful in future.

I am not going to start the war again about use of 3rd party tools, but using them for anything else other than code development is highly risky and not dependable. I use a GUI based tool only till the code development part, anything else I depend on what I know or ask people who know it. I wonder why people need to use a tool for optimizing something developed by themselves Shocked The person who wrote the sql would knows better than the stupid tool about what needs to be done to optimize it, isn't it?

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