Write short notes: B tree
B tree:
A B-tree is a tree structure where every node corresponds to a disk page and which satisfies the following properties:
A special case of the B-tree is when B = 2. Here every index node must have 2 or 3 or 4 child pointers. This special case is called the 2-3-4 tree. Figure 15.1 shows an example of a B-tree. In particular, it’s a 2-3-4 tree.
In the figure, every index node contains between 2 and 4 child pointers, and every leaf node contains between 2 and 4 objects. The root node A is an index node. Currently it has one object with key=25 and two child pointers. In the left sub-tree, every object has key25. Every leaf node (D through I) are located at the same depth: their distance to A is 2. Currently, there are two pages which are full: an index node B and a leaf node D.
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Iridium satellite system