Re: Oracle 11g - Invisible Indexes
- From: Carel-Jan Engel <cjpengel.dbalert@xxxxxxxxx>
- To: kaygopal@xxxxxxxxx
- Date: Tue, 21 Aug 2007 09:07:51 +0200
At least the invisible index will consume all the resources needed to
maintain it, which the NOSEGMENT index won't do.
That might look as a waste of time, OTOH, it also allows to measure its
resource consumption connected to all the DML, without hampering
execution plans for important queries.
Whatever, it seems some maturation has to be waited for.
It's sounds like a solution, looking for a problem to solve;-)
Best regards,
Carel-Jan Engel
===
If you think education is expensive, try ignorance. (Derek Bok)
===
On Mon, 2007-08-20 at 19:33 -0500, K Gopalakrishnan wrote:
> Robert,
>
> I got your point. However this same feature is already available in
> the form of NOSEGMENT indexes where you can create an index (with
> NOSEGMENT) and try the index using a little known undocumented
> parameter (_use_nosegment_indexes=true) at session level. We do that
> all the time before trying an index.
>
> I just see this as an extension of nosegment indexes..
>
> -Gopal
>
> On 8/20/07, Robert Freeman <robertgfreeman@xxxxxxxxx> wrote:
> > I rather suspect where Oracle is going with the
> > invisible index is associated with the automated SQL
> > tuning. Say, for example, Oracle reviews SQL that has
> > run and determines that an index would benefit the
> > execution plan. Why not create it as an invisible
> > index (thus, you don't impact other execution plans),
> > test it and quantify the performance and then, if you
> > get say 3 or 4x performance, you make it visible.
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