Re: Cost is higher but query is much faster

In article <1017298646.10137.1.nnrp-13.9e984b29_at_news.demon.co.uk>, "Jonathan says...
>
>
>It's another one for Rob Freeman to add
>to his "Favourite Urban Legends".
>

sounds like something to add to the FAQ ;) an "it's a myth -- REALLY" page.

I just had to talk about three of them this very morning:

o the most discriminating fields belong first in all indexes

o tables should have very very very few extents, one extent being the BEST

o index and data MUST be in separate tablespaces (mind you now, NOT different devices -- just different tablespaces, never mind we only have 1 mount point and it's a raid-5 "device" that consists of tons of real disk). Everyone knows that.

>
>--
>Jonathan Lewis
>http://www.jlcomp.demon.co.uk
>
>Next Seminar - UK, April 3rd - 5th
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>
>Host to The Co-Operative Oracle Users' FAQ
>http://www.jlcomp.demon.co.uk/faq/ind_faq.html
>
>Author of:
>Practical Oracle 8i: Building Efficient Databases
>
>
>Connor McDonald wrote in message <3CA240A9.23E3_at_yahoo.com>...
>>Alan wrote:
>>>
>>> Also, remember that the best CBO query will never perform any faster than
>an
>>> optimally constructed RBO query.
>>>
>>
>>Would you care to justify that remark?
>>
>>I'm dying to see how the RBO is going to handle a function based index..
>>
>>Cheers
>>Connor
>
>
>

--
Thomas Kyte (tkyte@us.oracle.com)             http://asktom.oracle.com/ 
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