Re: Cost Based Optimizer

From: Connor McDonald <mcdonald.connor_at_gmail.com>
Date: Fri, 20 May 2005 08:52:08 +0800
Message-ID: <5e304862050519175251b96f0b@mail.gmail.com>

• dynamic sampling
• session parameters (multi-block read, sort size, optimizer_ind_...., optimizer_mode)

If you run an explain with event 10053 set, the top part of the trace dumps out a list of parameters that may have had an influencing effect

hth
connor

On 5/20/05, Terry Barnett <tbarne_at_landmark-information.co.uk> wrote:

>=20
>=20

> I am having issues with execution plans changing even though the
> statistics on tables are kept static. Can anyone give me any information
> on the dynamic factors which are taken into account by the CBO when
> determining an execution plan and how one could detect that a plan may
> be about to change.

>=20

> Regards,
> Terry

>=20
>=20
>=20

--=20
Connor McDonald
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D
email: connor_mcdonald_at_yahoo.com
web: http://www.oracledba.co.uk

"Semper in excremento, sole profundum qui variat"

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Received on Thu May 19 2005 - 20:56:48 CDT