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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.
In the B+ tree, the internal nodes do not store any pointers to records, thus all pointers to records are stored in the leaf nodes. In addition, a leaf node may include a pointer to the next leaf node to speed up sequential access. [2] Because B+ tree internal nodes have fewer pointers, each node can hold more keys, causing the tree to be ...
To turn a regular search tree into an order statistic tree, the nodes of the tree need to store one additional value, which is the size of the subtree rooted at that node (i.e., the number of nodes below it). All operations that modify the tree must adjust this information to preserve the invariant that size[x] = size[left[x]] + size[right[x]] + 1
A B-tree can be seen as a very specialized form of n-ary tree, one that adds a pile of special restrictions. The restrictions make insertion and deletion a little more complicated -- but, in return, the B-tree can guarantee very fast searches. Some nodes in some n-ary trees have only 1 or 2 children. B-trees are constructed so every internal ...
I think it's fair to keep SQLite on that list as it is. The term "B+ tree" is only relevant when data records consist of a lookup field (e.g. table's primary key) and non-lookup data fields (rest of table data). In the case of regular database indexes, the whole index record is the lookup key, therefore a B+ tree and B-tree would be equivalent ...
Tree as a multidigraph (X, A, s, t), and the "arrow tree" generalization. The multidigraph definition of trees, showing a direct correspondence between reified arrows and hard-links in file systems. Tree as an unfolded accessible pointed graph / multidigraph. Trees as a special case of accessible pointed graphs / multidigraphs.
Trees can be used to represent and manipulate various mathematical structures, such as: Paths through an arbitrary node-and-edge graph (including multigraphs), by making multiple nodes in the tree for each graph node used in multiple paths; Any mathematical hierarchy; Tree structures are often used for mapping the relationships between things ...