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Home -> Community -> Mailing Lists -> Oracle-L -> Re: Re: optimizer_index_cost_adj and optimizer_index_caching
The reason is because one by one the database gave the same problem,
all of them are similar,
and the same solution worked.
And I think anything is better than default values( specifically with this tow parameters),
or I'm wrong.
If I correctly understand your post, what you are saying is that the init.ora parms O_I_C_A and O_I_C were set on all your databases because it helped a problem on two of them.
This is not generally considered a good practice, that is, making changes to a parameter with global implications without a specific reason for doing so, and the testing to back it up.
I once set these parameters on a database that houses an application of somewhat questionable design. It did help, but I was really only trying to fix a single query.
So, I put the shotgun back in the cabinet, pulled out the laser scalpal and created a histogram on a single column of a single table and solved the problem.
HTH Jared
"Juan Cachito Reyes Pacheco" <jreyes_at_dazasoftware.com>
Sent by: oracle-l-bounce_at_freelists.org
03/09/2004 12:25 PM
Please respond to oracle-l
To: <oracle-l_at_freelists.org>
cc:
Subject: Re: Re: optimizer_index_cost_adj and optimizer_index_caching
I asked and this how it happened
one database gave problem, then we found setting this parameters solved this
problem, then we set
them ONLY in one database
after about one year other database had the same problem, after some months
other,
then we decided to set it to all at once.
because the worload is between and oltp and a dss, we don't have to change
it.
That is why I suggest to set it, is better to have a more acurrate value set
in the database. in 9.2 windows
> the debate on this topic is exactly why we need to keep this list going.
Thanks for all your help guys.
> >
> > From: "Juan Cachito Reyes Pacheco" <jreyes_at_dazasoftware.com>
> > Date: 2004/03/09 Tue AM 08:19:01 EST
> > To: <oracle-l_at_freelists.org>
> > Subject: Re: optimizer_index_cost_adj and optimizer_index_caching
> >
> > I'm using, because in a specific database a query gave trouble, and I
fixed
> > it setting this parameters. Curiously in other production databases
(more
> > than 15) similar to that, didn't gave that problem.
> > But we decided to set it any way.
> > I think is better to set them, even when in most situation there is not
> > problems.
> > :)
> >
> > ----- Original Message -----
> > From: "Niall Litchfield" <n-litchfield_at_audit-commission.gov.uk>
> > To: <oracle-l_at_freelists.org>
> > Sent: Tuesday, March 09, 2004 5:01 AM
> > Subject: RE: optimizer_index_cost_adj and optimizer_index_caching
> >
> >
> > Thanks Joze and Wolfgang
> >
> > I'm in a position where gathering system stats seems to me to be the
Right
> > Thing (tm) to do, certainly an advance on setting parameters based on
> > guesses/measurements ahead of time. I hadn't until now seen any
indications
> > as to whether the feature worked as advertised or if in fact gathering
> > system stats introduced for example unexpected and unwanted plan
changes,
> > curious bugs etc etc. In fact I hadn't seen *any* feedback at all which
made
> > me suspicious that anyone was actually using it - I guess folks recall
the
> > introduction of the CBO which was equally the right thing to do but..
> >
> > Niall Litchfield
> > Oracle DBA
> > Audit Commission
> > +44 117 975 7805
> >
> >
> >
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