On Jul 20, 4:02 pm, Frank van Bortel <frank.van.bor..._at_gmail.com>
wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
>
>
> andreik wrote:
> > Hello,
>
> > The SQL Access Advisor, among other recommendations, generates the so
> > called "RETAIN INDEX" recommendations.
>
> > The recommended action itself looks something like this:
>
> > /* RETAIN INDEX "SCOTT"."PK_COLUMN_EMP" */
>
> > Which looks more like an optimizer hint...
>
> > I have looked through the oracle docs and googled it and not even in
> > the "ask tom" or metalink I could find a clear explanation to what
> > does this recommendation do?
>
> > Here:
> >http://download-uk.oracle.com/docs/cd/B19306_01/server.102/b14211/adv...
> > it says that:
> > "RETAIN recommendation indicate that existing access structures must
> > be kept"
>
> > This makes few sence to me.. Can anyone explain what does this...
> > ehm... statement(?) really do?
>
> > Is it so that oracle simply tells me that it was a good idea to create
> > that index and I should never drop it? But according to advisor
> > implementing these recommendations is supposed to reduce the total
> > cost. How can doing nothing reduce me the cost?
>
> It does not do anything, apart from telling you that
> this particular index is a useful one, and should be kept (retained).
>
> Some indexes could be dropped - some should be retained.
> It's the opposite of keeping.
> - --
> Regards,
> Frank van Bortel
>
> Top-posting is one way to shut me up...
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.4.1 (MingW32)
>
> iD8DBQFGoLJtLw8L4IAs830RArbDAJ9sSHmoZ91p8hIeok3SNDABo45RJQCZAYU6
> I5kmFu0UXleRDv923W4R6AE=
> =s9/x
> -----END PGP SIGNATURE-----
ok, that's what I thought. The most confusing about this was that
oracle includes these /* RETAIN INDEX blabla */ lines into the script
generated when you press the "implement recommendations".
Received on Fri Jul 20 2007 - 08:15:28 CDT
