Re: Plea for Query Tuning Help

  • From: "Ghassan Salem" <salem.ghassan@xxxxxxxxx>
  • To: "Norman Dunbar" <norman.dunbar@xxxxxxxxxxxxxxxxxxxxxxxxx>
  • Date: Wed, 13 Sep 2006 10:05:54 +0200

What I mean by "can decide" is that it will compute the costs with and
without materializing, and choose the lowest cost. So the hint is redundant,
but like all hints, they are there to help you in case CBO computes a wrong
cost for whatever reason.


On 9/13/06, Norman Dunbar <norman.dunbar@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

Morning "Ghassan Salem",

>> "Ghassan Salem" <salem.ghassan@xxxxxxxxx> 09/13/06 08:45am >>>
>> if you use the "view" several times in the query, CBO can decide to
>> materialize it, without the hint.

Thanks for that. One question - and I'm nit picking here - where you
say 'CBO can decide' do you mean it 'will always' or 'might' ?

In the latter case the hint would probably be benficial, in the former,
the hint os obviously redundant.

I'm asking because (a) I don't know and (b) I'm too lazy to look it up
at the moment :o)


Norman Dunbar.
Contract Oracle DBA.
Rivers House, Leeds.

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