BPlus-tree - B+ tree - Wikipedia, the free encyclopedia 1 /...

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B+ tree From Wikipedia, the free encyclopedia In computer science, a B+ tree (BplusTree) is a type of tree which represents sorted data in a way that allows for efficient insertion, retrieval and removal of records, each of which is identified by a key . It is a dynamic, multilevel index, with maximum and minimum bounds on the number of keys in each index segment (usually called a "block" or "node"). In a B+ tree, in contrast to a B-tree, all records are stored at the leaf level of the tree; only keys are stored in interior nodes. The primary value of a B+ tree is in storing data for efficient retrieval in a block-oriented storage context. This is primarily because unlike binary search trees, B+ trees have very high fanout (typically on the order of 100 or more), which reduces the number of I/O operations required to find an element in the tree. btrfs, NTFS, ReiserFS, NSS, XFS, and JFS filesystems all use this type of tree for metadata indexing. Relational database management systems such as IBM DB2 [1] , Informix [1] , Microsoft SQL Server [1] , Oracle 8 [1] , Sybase ASI [1] , PostgreSQL [2] , Firebird and MySQL [3] support this type of tree for table indices. Key-value database management systems such as Tokyo Cabinet [4] and Tokyo Tyrant support this type of tree for data access. Details The order (branching factor) of a B+ tree measures the capacity of nodes (i.e. the number of children nodes) in the tree. It is defined as a number d such that , where m is the number of children in each node. For example, if the order of a B+ tree is 7, each internal node (except for the root) may have between 4 and 7 children; the root may have between 2 and 7. A simple B+ tree example linking the keys 1–7 to data values d 1 -d 7 . Note the linked list (red) allowing rapid in-order traversal. Contents ± 1 Details ± 1.1 Search ± 1.2 Insertion ± 2 Characteristics ± 3 Implementation ± 4 History ± 5 See also ± 6 References ± 7 External links 페이지 1/±4 B+ tree - Wikipedia, the free encyclopedia 2009-11-25 http://en.wikipedia.org/wiki/B%2B_tree
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Search The algorithm to perform a search for a record r follows pointers to the correct child of each node until a leaf is reached. Then, the leaf is scanned until the correct record is found (or until failure).
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This note was uploaded on 04/20/2010 for the course CS CS206 taught by Professor Lee during the Fall '09 term at 카이스트, 한국과학기술원.

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BPlus-tree - B+ tree - Wikipedia, the free encyclopedia 1 /...

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