| Oracle FAQ | Your Portal to the Oracle Knowledge Grid | |
 |
 | |||
| Oracle FAQ | Your Portal to the Oracle Knowledge Grid | |
|
| |||
Home -> Community -> Mailing Lists -> Oracle-L -> RE: RE: Index-Organized Table experiences
FWIW -
Index-only tables (their IBM name) were in DB2 first, and have been
around for many, many years.
It's an excellent concept. Perhaps 30% of all the new tables I create qualify, especially with heavy normalization and the new capabilities to have secondary indexes...
Michael Fontana
Sr. DBA
NTT/Verio
-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Powell, Mark D
Sent: Wednesday, April 28, 2004 1:21 PM
To: 'oracle-l_at_freelists.org'
Subject: RE: RE: Index-Organized Table experiences
>From the Oracle version 9.2 Concepts manual >> Ch 10 section Secondary Indexes on Index-Organized Tables - Oracle constructs secondary indexes on index-organized tables using logical row identifiers (logical rowids) that are based on the table's primary key. A logical rowid optionally includes a physical guess, which identifies the block location of the row. <<
Secondary indexes contain a logical rowid in version 9+. Oracle looks for row at or near indexed logical rowid. If it finds it great. If it does not find the row then the primary index structure is searched using the PK.
Hope this clears up any confusion caused by my reply. The manual contains more details of exactly what Oracle does and the cost of stale guesses.
-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org]On Behalf Of Jared Still
Sent: Wednesday, April 28, 2004 1:51 PM
To: Oracle-L Freelists
Subject: Re: RE: Index-Organized Table experiences
Guess?
What does that mean?
An IOT is essentially a b*tree that is treated as a table.
What kind of guessing would be involved?
Jared
On Wed, 2004-04-28 at 10:15, ryan.gaffuri_at_cox.net wrote:
> We have alot of many to many relationships. IOTs sound like a good
> option.
However, our many to many relationships are in a high transaction
database. I remember reading that Oracle has to 'guess' the location of
IOTs and that if you perform alot of DML those guesses can be
inaccurate.
>
> anyone have experience with this?
>
-- Archives are at http://www.freelists.org/archives/oracle-l/ FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html ----------------------------------------------------------------- ---------------------------------------------------------------- Please see the official ORACLE-L FAQ: http://www.orafaq.com ---------------------------------------------------------------- To unsubscribe send email to: oracle-l-request_at_freelists.org put 'unsubscribe' in the subject line. -- Archives are at http://www.freelists.org/archives/oracle-l/ FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html ----------------------------------------------------------------- ---------------------------------------------------------------- Please see the official ORACLE-L FAQ: http://www.orafaq.com ---------------------------------------------------------------- To unsubscribe send email to: oracle-l-request_at_freelists.org put 'unsubscribe' in the subject line. -- Archives are at http://www.freelists.org/archives/oracle-l/ FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html -----------------------------------------------------------------Received on Wed Apr 28 2004 - 13:45:57 CDT
 |
 |