Re: Episode 2: the EntMgr Green Light!!

"Domenic G." <domenicg_at_hotmail.com> wrote in message news:c7e08a19.0311081244.7f0acdb_at_posting.google.com...
> Niall,
>
> Thanks for your input. I have a few questions ...
>
> What is the purpose of a reverse-key index then? Surely the guys at
> Oracle who can actually see inside the code know more than us?
>
> I'm only doing what Oracle taught me to do. They should know their
> product. Are you saying they're wrong?
>
> Sometimes DBAs have nothing to do. At least by doing these things, I
> feel like I'm being proactive, even if the benefit is negligible or
> none. Besides, the system is idle overnight, so why can't I schedule
> these rebuilds? -- they're not locking anybody out or doing harm.
>
> Wouldn't a more compact index reduce I/O? In university, I wrote C++
> code to implement b-tree indexes and I'm not sure what you're saying
> is true. The index is always better organized when it is rebuilt by
> scanning all the data in the table. It depends on the datatype and
> the exact methodology. So while I do understand your point, my point
> is this -- without actually looking inside a block or seeing Oracle's
> code, you're guessing as much as I am. I'm just following their
> recommendations, and that's all I can do since their source is not
> open.
>
> Dom.
>
>
>
>
> "Niall Litchfield" <niall.litchfield_at_dial.pipex.com> wrote in message
news:<3facffdd$0$5413$cc9e4d1f_at_news.dial.pipex.com>...
> > "Domenic G." <domenicg_at_hotmail.com> wrote in message
> > news:c7e08a19.0311071536.59d4125a_at_posting.google.com...
> > > Why would vendors care if I rebuild one of their indexes.
> >
> > Well I hope I gave at least some reasons why your 2 minute phone call to
the
> > vendor might not have been a waste of time.
> >
> > > Is there a
> > > law banning it somewhere?
> >
> > Lw 530, Subsection 2, Paragraph 1 "the ladybird big book of laws" .:)
> >
> > > Documented procedures are for drones or
> > > monkeys -- level 1 support, not for trained professionals.
> >
> > Tosh. If you can't see the benefit of documented repeatable behaviour
then
> > you are probably appropriating the word professional inappropriately.
> >
> > > Screw support contracts -- they're just an excuse to do nothing.
> >
> > No they define rights and expectations on both sides, like all contracts
do.
> > I assume you never call your vendors since you don't expect any help
from
> > them?
> >

take a look at this as to why you shouldnt rebuild indexes

http://asktom.oracle.com/pls/ask/f?p=4950:8:::::F4950_P8_DISPLAYID:6601312252730

Rebuilding indexes really is a myth nowadays, maybe you had to in previous versions - but not now.
By rebuilding you could be hurting performance and then one day it will all go wrong you will be in trouble, whereas if you dont touch it, your system is fine and nobody is going to get hurt.

When you are you are being proactive - what are you trying to prevent by doing it? There are far more things you can do to be pro-active and help keep your system in good working order

People are guessing when they say they dont need to be rebuilt - it comes from cold hard facts and proving it with real test cases. These are also well respected in the Oracle world and are known worldwide - there statements should generally be believed as it is not an opinion in this case, just plain hard facts.

Take a look at this for reverse key indexes

http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96524/c11schem.htm#13369 Received on Sat Nov 08 2003 - 15:05:38 CST