Message-ID: <F001.00426AEA.20020313013830@fatcity.com>
Date: Wed, 13 Mar 2002 01:38:30 -0800
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From: "Jonathan Lewis" <jonathan@jlcomp.demon.co.uk>
Subject: Re: bitmap index with nosort
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Offline -

I'm sure you already know this, but technically they
are stored in a tree format, loosely speaking as an
IOT with columns:

    {column values(s)}, starting rowid, ending rowid, {string of bits}

where the {string of bits} is the 'data' component of the IOT, and
the rest is the 'primary key'.

In principle there is no reason why the NOSORT option
shouldn't apply to bitmap indexes. I would guess that
in practice because the sorting requirement is so small
compared to the bitmap generation strategy, no-one has
bothered to put the code in place.


Jonathan Lewis
http://www.jlcomp.demon.co.uk

Next Seminar - UK, April 3rd - 5th
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-----Original Message-----
To: Multiple recipients of list ORACLE-L <ORACLE-L@fatcity.com>
Date: 13 March 2002 08:44


|Sinardy :
|
|It is expected behavior only. Bit map indexes are not stored in a
tree
|format and sorting will have no impact.
|Have a look at bit map concepts in Oracle Documentation.
|
|
|Best Regards,
|K Gopalakrishnan
|Bangalore, INDIA
|


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Author: Jonathan Lewis
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