Re: The optimizer is ignoring my hints


Clearly you haven't yet discovered the 
    ignore_optim_embedded_hints
hint.

So if you include this hint as an embedded hint,
does Oracle ignore it ?

I haven't tested the parameter yet - but here's another
interesting thought. Oracle Corp. includes hidden boolean 
parameters so that they can be changed in some future release.
They must be getting confident.

In answer to your previous question - I think this hint, and
the description of the parameter, gives the clue about 
profiles, and outlines - the only hints ignored are the
embedded ones (i.e. the ones you put in the SQL), the
one stored in the database for a query still apply.
(I've only tested this for outlines, though).

Regards

Jonathan Lewis

http://www.jlcomp.demon.co.uk

http://www.jlcomp.demon.co.uk/faq/ind_faq.html
The Co-operative Oracle Users' FAQ

http://www.jlcomp.demon.co.uk/seminar.html
Optimising Oracle Seminar - schedule updated May 1st


----- Original Message ----- 
From: "Niall Litchfield" <niall.litchfield@xxxxxxxxx>
To: <oracle-l@xxxxxxxxxxxxx>
Sent: Monday, May 24, 2004 11:37 AM
Subject: The optimizer is ignoring my hints


Yes I know we did this to death a little while back - I believe that I
may have said words to the effect that the CBO never *ignores* valid
hints but that you may not get the execution plan you expect if you
don't specify enough.

Consider the following 10053 extracts using the same old scott/tiger demo

The difference between them - a new parameter for 10g

  *************************************
  PARAMETERS WITH ALTERED VALUES
  ******************************
<snip>
  _optimizer_ignore_hints             = true

So it would seem that having just about settled the whole the
optimizer is ignoring my hint debate - now it can.



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