Re: Maximum height of an Oracle B-tree index
- From: "Richard Foote" <richard.foote@xxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 11 Mar 2004 08:31:25 +1000
Hi Jared/Tin and all,
I believe that was precisely how Steve managed it, very small block size, large
pctfree, a bit of cleverness and heaps of storage (until it ran out). He
mentioned it btw at the Hotsos tuning class in Sydney last year.
So far the best I've heard privately is height of 6.
Can anyone do better ?
Cheers
Richard
----- Original Message -----
From: Jared.Still@xxxxxxxxxxx
To: oracle-l@xxxxxxxxxxxxx
Sent: Thursday, March 11, 2004 6:46 AM
Subject: Re: Maximum height of an Oracle B-tree index
My thoughts mirrored Tims.
Though after seeing Jonathan Lewis force a very small index
to a blevel of 3 with the clever use of data and storage parms
and who knows what else, I decided there was a distinct possibility
that I was wrong.
I've refrained from asking Steve how he did this, but if I see him
at dinner this evening, I will find out and report back. :)
Jared
Live from HOTSOS
Tim Gorman <tim@xxxxxxxxxxxxx>
Sent by: oracle-l-bounce@xxxxxxxxxxxxx
03/10/2004 06:08 AM
Please respond to oracle-l
To: <oracle-l@xxxxxxxxxxxxx>
cc:
Subject: Re: Maximum height of an Oracle B-tree index
It would take a heckuva lot of space, even with DB_BLOCK_SIZE = 512 and
PCTFREE=99 on the index, to get BLEVEL over 10...
Hat's off to Steve on getting it to 20+...
on 3/9/04 7:18 AM, Richard Foote at richard.foote@xxxxxxxxxxx wrote:
> Hi All,
>
> I'm currently writing a rather detailed paper for our local user group on
> Index Internals, tentatively titled "Index Internals - Rebuilding The
> Truth". I haven't had this much fun with tree and block dumps for quite a
> while ;)
>
> One of the many myths I'm exposing is the "rebuild if index has more than 2,
> 3, 4, 42, whatever levels". Now to get an honary mention in the paper (what
> more reward can one wish for !!), I would love to know who on the list has
> created an index with the greatest height and perhaps a little info on it's
> circumstance.
>
> Steve Adams once mentioned to me creating an index with 20+ levels, can
> anyone else come close ?
>
> Thanks for any replies.
>
> Richard
>
>
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