Ryan, From what I can remember, it was a good few years ago, DB2 trys to minimize index page splits and hence keep index levels to a minimum. It had the notion of sub-pages within an index page for locking puposes (it didn't do row-level locking then, I don't know about now). This sub-paging meant that it was inherently less space efficient than Oracle and therefore probably not as good at minimising the number of index levels. I stand to be corrected by those with more up todate / better knowledge than me. Chris Quoting Ryan <ryan.gaffuri@xxxxxxx>: > Is oracle the only database that is good at keeping the number of levels in > an index to a minimum? Or is it common amongst the other major dbms? > ----- Original Message ----- > From: "Cary Millsap" <cary.millsap@xxxxxxxxxx> > To: <oracle-l@xxxxxxxxxxxxx> > Sent: Thursday, February 05, 2004 11:04 PM > Subject: RE: How does Oracle keep B-tree indexes to 3 levels? > > > > 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 > > Hotsos Enterprises, Ltd. > > http://www.hotsos.com > > * Nullius in verba * > > > > Upcoming events: > > - Performance Diagnosis 101: 2/24 San Diego, 3/23 Park City, 4/6 Seattle > > - SQL Optimization 101: 2/16 Dallas > > - Hotsos Symposium 2004: March 7-10 Dallas > > - Visit www.hotsos.com for schedule details... > > > > > > -----Original Message----- > > From: oracle-l-bounce@xxxxxxxxxxxxx > > [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Ryan > > Sent: Thursday, February 05, 2004 9:32 PM > > To: oracle-l@xxxxxxxxxxxxx > > Subject: How does Oracle keep B-tree indexes to 3 levels? > > > > I'm taking an academic database class. My professor showed us that when > > you have a block split and the parent node(s) split, you end up with a > > new level. I'm assuming oracle 'redistributes' the pointers instead of > > adding a new level? > > Are index nodes always one block? > > ---------------------------------------------------------------- > > Please see the official ORACLE-L FAQ: http://www.orafaq.com > > ---------------------------------------------------------------- > > To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx > > put 'unsubscribe' in the subject line. > > -- > > Archives are at //www.freelists.org/archives/oracle-l/ > > FAQ is at //www.freelists.org/help/fom-serve/cache/1.html > > ----------------------------------------------------------------- > > > > ---------------------------------------------------------------- > > Please see the official ORACLE-L FAQ: http://www.orafaq.com > > ---------------------------------------------------------------- > > To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx > > put 'unsubscribe' in the subject line. > > -- > > Archives are at //www.freelists.org/archives/oracle-l/ > > FAQ is at //www.freelists.org/help/fom-serve/cache/1.html > > ----------------------------------------------------------------- > > ---------------------------------------------------------------- > Please see the official ORACLE-L FAQ: http://www.orafaq.com > ---------------------------------------------------------------- > To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx > put 'unsubscribe' in the subject line. > -- > Archives are at //www.freelists.org/archives/oracle-l/ > FAQ is at //www.freelists.org/help/fom-serve/cache/1.html > ----------------------------------------------------------------- > Chris Dunscombe chris@xxxxxxxxxxxxxxxxxxxxx ------------------------------------------------- Everyone should have http://www.freedom2surf.net/ ---------------------------------------------------------------- Please see the official ORACLE-L FAQ: http://www.orafaq.com ---------------------------------------------------------------- To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx put 'unsubscribe' in the subject line. -- Archives are at //www.freelists.org/archives/oracle-l/ FAQ is at //www.freelists.org/help/fom-serve/cache/1.html -----------------------------------------------------------------