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The term B-tree may refer to a specific design or it may refer to a general class of designs. In the narrow sense, a B-tree stores keys in its internal nodes but need not store those keys in the records at the leaves. The general class includes variations such as the B+ tree, the B * tree and the B *+ tree.
A B+ tree is an m-ary tree with a variable but often large number of children per node. A B+ tree consists of a root, internal nodes and leaves. [ 1 ] The root may be either a leaf or a node with two or more children.
Database tables and indexes may be stored on disk in one of a number of forms, including ordered/unordered flat files, ISAM, heap files, hash buckets, or B+ trees. Each form has its own particular advantages and disadvantages. The most commonly used forms are B-trees and ISAM.
The non-clustered index tree contains the index keys in sorted order, with the leaf level of the index containing the pointer to the record (page and the row number in the data page in page-organized engines; row offset in file-organized engines). In a non-clustered index, The physical order of the rows is not the same as the index order.
B-trees are a variant of (a,b) trees, so the (a,b) tree article should contain pretty much everything except stuff like the fact that a = B/4 and b = B/2 in a B-tree. Moved this text to the discussion section from the main definition. Chadloder 18:34 Jan 22, 2003 (UTC) The original author interchanged between B+-tree and B-tree.
B+ tree; Bx-tree; D. Dancing tree; H. HTree This page was last edited on 31 August 2018, at 13:26 (UTC). Text is available under the Creative Commons Attribution ...
Note (11): R-Tree indexing available in base edition with Locator but some functionality requires Personal Edition or Enterprise Edition with Spatial option. Note (12): FOT or Forest of Trees indexes is a type of B-tree index consisting of multiple B-trees which reduces contention in multi-user environments. [126]
These statements are misleading, and technically incorrect. B+ Trees are an extension to B-trees, and as such are typically used as indexes for commercial database systems. The B+ Tree comprises two parts: a sequential index containing an entry for every record in the file, and a B-tree acting as a multilevel index to the sequential index entries.