Re: Seeking advice on potential 10g upgrade
- From: "Niall Litchfield" <niall.litchfield@xxxxxxxxx>
- To: Brandon.Allen@xxxxxxxxxxx
- Date: Tue, 29 Aug 2006 09:52:34 +0100
I'd take a look at http://www.jlcomp.demon.co.uk/hinted_sql.html for
some further discussion of whether the system is likely to be more
stable or run into issues in the presence of many hinted sql
statements.
Plan Stability is indeed a set of hints, its the main evidence that I
use when I state that a hint is a directive, rather than a 'hint' in
the english sense of the word, it's worth noting however the number of
hints that Plan Stability tends to find necessary to produce a locked
in execution plan, and compare to the typical use of hints by
developers. for example many developers would write code like
select
/*+ USE_NL(a,b) */ <cols>
from
a, b
where <criteria>
and consider that this ensured that Oracle would use a nested loops
join for the query.
On 8/28/06, Allen, Brandon <Brandon.Allen@xxxxxxxxxxx> wrote:
With all due respect I have to disagree with you on that. In many cases
hints can make query execution more stable. After all - Oracle's own
"Plan Stability" feature (a.k.a Stored Outlines) is really just a bunch
of persistent internal hints. So, it depends on what hints are used,
but if they are just simple index and join method hints - they might
actually make things more stable/predictable through an upgrade.
> -----Original Message-----
> From: oracle-l-bounce@xxxxxxxxxxxxx
> [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Kevin Closson
> Sent: Monday, August 28, 2006 11:56 AM
> To: oracle-l@xxxxxxxxxxxxx
> Subject: RE: Seeking advice on potential 10g upgrade
>
> >>>I know that they have made liberal use of optimizer
> hints, and I'm afraid that those may cause us grief if we upgrade.
>
> ...that's a good bet.
>
>
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Niall Litchfield
Oracle DBA
http://www.orawin.info
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