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Home -> Community -> Mailing Lists -> Oracle-L -> Re: RE: How does Oracle keep B-tree indexes to 3 levels?
how does oracle determine underflow? In class the professor said that if =
a block is less than 1/2 full the block is either merged with another blo=
ck if it can fit, or the data is redistributed amongst multiple blocks. =
Oracle doesn't have a pctused for indexes. The pctfree is the overflow. D= oes oracle use the 1/2 full line for underflow? =
> =
> From: Connor McDonald <hamcdc_at_yahoo.co.uk>
> Date: 2004/02/06 Fri AM 08:20:29 EST
> To: oracle-l_at_freelists.org
> Subject: Re: RE: How does Oracle keep B-tree indexes to 3 levels?
> =
> x
> / \
> x x
> =
> This is my pictorial representation of a simple b-tree index. A simple=
r one follows:
> =
> x
> =
> hth
> connor
> =
> --- ryan.gaffuri_at_cox.net wrote: > academic textbooks have them. The si=
lbershatz book 'database
> systems concepts' has it in chapter
> > 12. =
> > > =
> > > From: "Prem Khanna J" <jprem_at_kssnet.co.jp>
> > > Date: 2004/02/05 Thu PM 11:57:29 EST
> > > To: <oracle-l_at_freelists.org>
> > > CC: <cary.millsap_at_hotsos.com>
> > > Subject: RE: How does Oracle keep B-tree indexes to 3 levels?
> > > =
> > > Hi Cary & List ,
> > > =
> > > i have been long trying to get a pictorial representation
> > > of a simple b-tree index and how it changes as the =
> > > index grows . Though i read the docs , still i'm not
> > > able to say "okay , this is how b-tree index works" .
> > > =
> > > Has anyone got something like what i'm looking for ?
> > > =
> > > Just curious to know : =
> > > Cary , what does * Nullius in verba * mean ? =
> > > =
> > > Regards,
> > > Prem.
> > > =
> > > >>-----Original Message-----
> > > >>From: oracle-l-bounce_at_freelists.org =
> > > >>
> > > >>You get a new level only if the parent node splits propagate =
> > > >>all the way
> > > >>to the index root node. Jonathan Lewis and Steve Adams have some =
good
> > > >>tests in their courses that use block dumps to show how Oracle
> > > >>redistributes keys in branch blocks when nodes split.
> > > >>
> > > >>Yes, Oracle index nodes are one block apiece.
> > > =
> > > >>Cary Millsap
> > > >>* Nullius in verba *
> > > =
> > > ----------------------------------------------------------------
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> =
> =3D=3D=3D=3D=3D
> Connor McDonald
> Co-author: "Mastering Oracle PL/SQL - Practical Solutions" - available =
now
> web: http://www.oracledba.co.uk
> web: http://www.oaktable.net
> email: connor_mcdonald_at_yahoo.com
> =
> "GIVE a man a fish and he will eat for a day. But TEACH him how to fish=
, and...he will sit in a boat and drink beer all day"
> =
> =
> =
> =
> =
> ___________________________________________________________
> BT Yahoo! Broadband - Free modem offer, sign up online today and save =A3=
80 http://btyahoo.yahoo.co.uk
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-- 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 Fri Feb 06 2004 - 07:34:48 CST
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