Re: Re: optimizer_index_cost_adj and optimizer_index_caching
- From: "Juan Cachito Reyes Pacheco" <jreyes@xxxxxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Tue, 9 Mar 2004 17:23:56 -0400
This is more acurrate for me (more acurrate than the default values)
OPTIMIZER_INDEX_COST_ADJ = 10 # Cambiar a 50 en datawarehousing
OPTIMIZER_INDEX_CACHING = 90 # No cambiar, posibilidad de encontrar
indice en cache
But could you please giveme an example, I never did that
And I agre this approach is not too scientific, but this is the advice I got
before
to set them and then try distinct values.
I runed dbms_stats.gather_system_stats
And this is from sys.aux_stats$ :) as you said, but I don't know how can I
set them based on this.
SNAME PNAME PVAL1
PVAL2
------------------------------ ------------------------------ --------------
------------------------- --------------------------------------------------
----------------------------------------------------------------------------
----------------------------------------------------------------------------
-----------------------------------------------------
SYSSTATS_INFO STATUS
NOWORKLOAD
SYSSTATS_INFO DSTART
03-09-2004 17:20
SYSSTATS_INFO DSTOP
03-09-2004 17:20
SYSSTATS_INFO FLAGS 1
SNAME PNAME PVAL1
PVAL2
------------------------------ ------------------------------ --------------
------------------------- --------------------------------------------------
----------------------------------------------------------------------------
----------------------------------------------------------------------------
-----------------------------------------------------
SYSSTATS_INFO STATUS
NOWORKLOAD
SYSSTATS_INFO DSTART
03-09-2004 17:20
SYSSTATS_INFO DSTOP
03-09-2004 17:20
SYSSTATS_INFO FLAGS 1
----- Original Message -----
From: "Mladen Gogala" <mladen@xxxxxxxxxxxxxxx>
To: <oracle-l@xxxxxxxxxxxxx>
Sent: Tuesday, March 09, 2004 5:11 PM
Subject: Re: Re: optimizer_index_cost_adj and optimizer_index_caching
> More accurate value? What is "more accurate value"? If you want accurate
values,
> you have dbms_stats.gather_system_stats and sys.aux_stats$ table.
> What you want is to make CBO work like RBO and you succeeded.
>
> On 03/09/2004 03:25:55 PM, Juan Cachito Reyes Pacheco wrote:
> > 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
> > ----- Original Message -----
> > From: <ryan.gaffuri@xxxxxxx>
> > To: <oracle-l@xxxxxxxxxxxxx>
> > Sent: Tuesday, March 09, 2004 9:36 AM
> > Subject: Re: Re: optimizer_index_cost_adj and optimizer_index_caching
> >
> >
> > > 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@xxxxxxxxxxxxxxxx>
> > > > Date: 2004/03/09 Tue AM 08:19:01 EST
> > > > To: <oracle-l@xxxxxxxxxxxxx>
> > > > 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@xxxxxxxxxxxxxxxxxxxxxxx>
> > > > To: <oracle-l@xxxxxxxxxxxxx>
> > > > 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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