RE: RE: Index-Organized Table experiences
- From: "Powell, Mark D" <mark.powell@xxxxxxx>
- To: "'oracle-l@xxxxxxxxxxxxx'" <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 28 Apr 2004 14:20:35 -0400
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.
-- Mark D Powell --
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx]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@xxxxxxx 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?
>
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