RE: Antw: RE: I wanna know how Oracle uses file organization in

A B-Tree is not a binary structure, but an n-ary one. A true binary tree bifurcates, By that I mean Root node A connects to branch nodes C and D, Branch node C connects to branch nodes E and F. Branch Node D connects to branch nodes G and H and so forth. Each node is directly connected to two other nodes progressing from the root to the leaves.

This just is not true in a B-Tree. In a B-Tree the branching is not always two-way. Root node A may directly connect to nodes B, C and D. B may connect to E, F, G, H and I, C to J, K, and L, ands D to M, N, O, P, Q, R and S. The 7 connects form D to its child nodes are the most in this example. This tree is said to be of order 7.

See "The Art of Computer Programming" (Vol. 3 Sorting and Searching) by Donald Knuth.

The real mark of a B-Tree is that all leaves are at the same level. This is not usually true for a binary tree. You should understand the basic inserting and splitting process which makes the first statement possible.

I used to think that perhaps the B meant balanced. But the term balanced-tree refers to a structure first defined by two Russian mathematicians in a paper published 1962. The true B-tree was defined in 1970 and its structure published in 1972.

Ian MacGregor
Stanford Linear Accelerator Center
ian_at_SLAC.Stanford.edu               

-----Original Message-----
Sent: Thursday, October 30, 2003 10:49 PM To: Multiple recipients of list ORACLE-L

Hi Sinardy,

one little correction: you forgot the winking smiley at the end of your last sentence ;-)

Greetings,
Guido

>>> SinardyXing_at_bkgcomsvc.com 31.10.2003 05.39 Uhr >>>
Hi Thai,

B-tree is short for binary tree, Indexing method make use of Binary search function to fast retrieve your records, therefore require sorted records. B+ tree (I don't know this one, never heard)

Go to www.Oracle.com download the document for free.

Reading order:

1. Concept
2. SQLPlus
3. DB Admin
4. Backup and Recovery
5. Network

After you finish all of these you have basic skill, you can be an Oracle DBA.

Good luck.

Sinardy

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