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Re: ORA 8 optimizer really bad!

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: 2000/03/07
Message-ID: <952455741.12740.2.nnrp-13.9e984b29@news.demon.co.uk>#1/1

The problem is that the Oracle 7 optimiser was easy to understand -

What are your data distributions like ? Any heavily skewed columns ?

If all else fails, try init.ora

optimizer_index_cost_adj = 1
optimizer_index_caching = 100

--

Jonathan Lewis
Yet another Oracle-related web site:  http://www.jlcomp.demon.co.uk

Frank van Bortel wrote in message <38C57BAF.EFDEB682_at_vnl.nl>...

>Franz Mueller wrote:
>
>> On 27 Jan 2000 15:17:37 EST, "Daniel" <delj_at_flash.net> wrote:
>>
>> I forgot to say that the tables were freshly analyzed, of course.
>>
>> >I see.... the database is not just supposed to use the indexes you
create.
>> >I understand what you are saying but this is an RDBMS. All of this is
>> >supposed to be automatic. It has been automatic. If I do a select
>> >somefield from sometable where somekey = 'somevalue'; the database
should
>> >use the index if it is there. That is the primary purpose of having an
>> >optimizer. My point is, I never had to do this in Oracle 7.x. I am
having
>> >to do this in 8.x. In addition, some of the optimizer problems were not
>> >resolved by computing statistics.
> >
>
>Just wondering... did you analyze the indexes as well?
>
>--
>Met vriendelijke groet/kind regards,
>
>Frank van Bortel
>Technical consultant Oracle
>
>
Received on Tue Mar 07 2000 - 00:00:00 CST

Original text of this message

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