Re: optimizer_ ???

From: Niall Litchfield <niall.litchfield_at_gmail.com>
Date: Tue, 26 Apr 2005 20:45:43 +0100
Message-ID: <7765c897050426124523aae2c2@mail.gmail.com>

On 4/26/05, Christian Antognini <Christian.Antognini_at_trivadis.com> wrote:
> Niall

>=20


> >Ah yes, indeed I have just such an example in my recent blog on oic

> >and oica (it was oica that had a similar effect for us) :) The

> >original question though was after an example of improved performance
> >rather than changed plans

>=20
> Mhmm... I don't understand... if the execution plan doesn't change, how t=
o get better performance?

That's because I wasn't clear:)=20

There are plenty of examples on the net that say in effect

1. determine execution plan
2. change oic, or oica, or both at the same time.=20
3. see - plans have changed.=20

they *don't* say

4. see - performance improved by x%.=20

showing me that if you change a parameter the plan will change tells me very little about performance - it does tell me about a bit about behaviour, showing me response time does and - so far as I can tell - there aren't any examples of improved response time from setting these parameters. Its as if the tuning goal has become 'favour nested loops' rather than 'impove end-user experience'.

--=20
Niall Litchfield
Oracle DBA
http://www.niall.litchfield.dial.pipex.com

--
http://www.freelists.org/webpage/oracle-l

Received on Tue Apr 26 2005 - 15:49:59 CDT