RE: Index rebuilding
- From: "Goulet, Dick" <DGoulet@xxxxxxxx>
- To: <oraclel@xxxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 12 Nov 2004 13:40:31 -0500
Looked at Richard Foote's paper. Don't know about that. I did prove to
OTS several years ago that a block could get "lost" in an index due to
deletion/updates that left it empty. I believe that got finally fixed
in Oracle 8i. I've still seen cases of index's becoming unbalanced, I
know the docs day it's impossible, but it does happen without the index
height increasing. And I still believe that index deletes don't get
flushed so efficiently, as Richard suggests. If that was the case then
I can't explain why an index rebuild can cause an index to shrink by 30%
or more. And recent experience still shows that a rebuild can cause
significant performance improvement. And Oracle has provided the
capability to rebuild indexes which is not trivial. Therefore, NEVER
use the word "never" unless your absolutely certain that under all
circumstances it will be absolutely true. And in the current context,
that is the truth, that is, never can never be an absolute.
BTW: Since we've a few "myth busters" in the group. I appreciate the
effort these people put into "myth busting", even if they are later
proven to have erred. At a very minimum they start discussion and
re-examination of commonly held beliefs that can have changed or lost
significance over the years(like it's best to have all of a tables data
in the first extent). Such discussion, although sometimes the start of
"Holy Wars", is healthy (not the Holy War though) and a necessary part
of all of us growing. That being said, let it be noted that I agree to
disagree, in part, with Mr Foote.
Dick Goulet
Senior Oracle DBA
Oracle Certified 8i DBA
-----Original Message-----
From: Jared Still [mailto:jkstill@xxxxxxxxx]=20
Sent: Friday, November 12, 2004 12:44 PM
To: oraclel@xxxxxxxxxx
Cc: oracle-l@xxxxxxxxxxxxx; steve@xxxxxxxxxxxxxx
Subject: Re: Index rebuilding
On Fri, 12 Nov 2004 11:49:46 +0100, Karsten Weikop <oraclel@xxxxxxxxxx>
wrote:
> Please read the execellent paper from Richard Foote (which can be
> downloaded from Miracle's site):
> http://www.miracleas.dk/images/upload/Docs/Richard%20Foote.pdf
> Conclusion form this paper: Never Rebuild, but find the course to the
> problem.
Never?
I think you will find that statement as difficult to support as
'always rebuild'.
--=20
Jared Still
Certifiable Oracle DBA and Part Time Perl Evangelist
--
//www.freelists.org/webpage/oracle-l
--
//www.freelists.org/webpage/oracle-l
Other related posts:
