Re: Maximum height of an Oracle B-tree index

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Wed, 17 Mar 2004 22:46:31 -0000
Message-ID: <002f01c40c74$26b3be30$7102a8c0@Primary>

Notes inline;

Regards

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

The Co-operative Oracle Users' FAQ
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Original Message ----- From: "Tanel Poder" <tanel.poder.003_at_mail.ee> To: <oracle-l_at_freelists.org> Sent: Wednesday, March 17, 2004 8:43 PM Subject: Re: Maximum height of an Oracle B-tree index

: Hi!
:
: > Got to a blevel of 20. There is rumored to be hard limit
: > of 23 levels on a b*tree index as implemented by Oracle,
: > maybe I will give that a try later.
:
: I remember a max height of 22 from 8i Data Server Internals materials, but
I can check it when I get home in few weeks.
:
: Of course testing it out would be the best way to find the limit.
:

This would require a 4M block, 8GB index in the smallest possible test, of course.

Here's a thought - is there a 4M (power(2,22)) block limit on a single segment ? I didn't think so, but it is the limit on the number of blocks in a single file. Might this have anything to do with a height limit of 22 which is, after all, an odd height since it isn't anything to do with a number of bits being set.

(So far I've got to height 17, but I might leave an all-nighter running to see if I can hit 22).

: Tanel.

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Received on Wed Mar 17 2004 - 17:00:33 CST