B+Trees

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The variation of a B-Tree that is most often implemented in the B+ Tree. In this tree, internal nodes store only keys and all the data is stored in the leaves. The keys are simply “sign posts” to direct a search to the proper leaf. In addition, nodes have sibling pointers, so that the nodes at each level form a linked list.

While B-Trees have many uses, a common use is to implement the directory structure of an operating system’s file system using B-Trees. The key idea is that one node of the tree is the same size as a disk block.